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Changing Earth’s Landforms
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Have you ever been to one of Florida’s beaches and watched the sand? You may have seen the sand being moved by the water, but what about the wind? Whether in Florida, in another state, or just close to home, you may have noticed that the land changes and has different features.
1. How many landforms do you . How know of that cany change over time?
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There are a variety of landforms across Earth’s surface. Landforms are the physical features of the surface of Earth. Some examples are coastlines, dunes, rivers, mountains, glaciers, deltas, and lakes. Landforms do not stay the same over time. Landforms are created and changed by processes such as weathering, erosion, and deposition.
Weathering is the process by which rocks are broken down into sediments slowly over time. There are two major types of weathering: physical and chemical. Physical weathering breaks down rocks into smaller pieces—called sediments through physical processes. Physical weathering changes the shape and size of a rock, but it does not change the rock’s chemical composition. Chemical weathering breaks down rocks through chemical processes that change their chemical composition. Some rocks, such as limestone, can be dissolved by water. Other compounds that are dissolved in the water can cause additional chemical reactions with the elements in the rock. Chemical compounds in the air can also cause chemical reactions that weather rocks. Many rocks contain minerals that are composed of the element iron. Chemicals in water and air can cause the iron in these minerals to rust or oxidize, changing the iron into iron oxide.
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locations. Although weathering and erosion often happen at the same time, they are not the same process. Weathering is the process by which rocks are broken down. Erosion is the process by which rocks, sediments, or soil is carried away. The main agents of erosion are water and wind, but gravity and ice can also cause erosion.
Sediments, rocks, and soil cannot keep moving forever. Eventually, the particles stop moving and settle where the erosional agents have carried them. This process is called deposition. When sediments are
oldest layer of sediments is positioned at the bottom, and the more recently deposited layers are at the top. Depending on which agents caused the erosion, the sediments may be deposited in different ways.
As we cover each type of landform in the coming sections, we will discuss the processes that form and change each of them.
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2. Can you think of some landforms thi 2. Can you that are changed by each process of that are chang weathering, erosion, and eathering,deposition? er hering,
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There are seven continents on Earth. The United States is part of one continent, North America. Florida is one state that is a peninsula, bordered on the west by the Gulf of Mexico and on the east by the Atlantic Ocean. Millions of years ago, Florida was completely covered by the ocean and then resurfaced to create the landforms that you see today.
As a peninsula, Florida has 1,200 mi. of coastline, including 700 mi. of beaches. A coastline is a narrow area of land where the land meets a body of water. Along Florida’s beaches, the coastline is constantly changing due to physical weathering and erosion by water as the tides rise and fall and waves crash on beaches and moves materials to other locations. The coast can also be rocky and steep, like some places down over time. A coastline can also be a place where land meets water in a lake or pond.
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sand dune is a landform that forms when sand is deposited in one place by water or wind. Dunes form in windy places such as beaches or deserts. A dune in Florida is a structure that is always a part of a beach. Dunes run parallel to the coastline and are sandy. Most dunes in Florida have plant life growing on them.
Florida is known for its beaches and attracts many tourists. As the tourism industry grew, people were disappointed that hilly dunes blocked their views of the beaches. Many places removed the plants and
with plants did the job of protecting the coastline and the sand on the beaches from erosion. When storms come in, the plants hold the sand in place so that it does not wash out to the ocean.
3. Do you think that we should keep Do natural dunes?d Should we replant them in areas where they were removed? Is thewe health of a beach more important than what the visitors want?
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Besides the ocean, there are landforms that are near water or contain water, such as lakes, rivers, and deltas. Florida is home to many lakes. Lakes are stable, nonmoving bodies of water that are surrounded by land and make up
into a basin or low area of land. Many of Florida’s lakes are naturally occurring, meaning they were shaped by nature with little to no interference from humans. Lakes must have a continual source of water, or they dry up. The shape, water
Florida began to be inhabited by European settlers. Humans use the water from the lakes in Florida for our purposes, but the structure and existence of the lakes have not been altered much. Lake Okeechobee is still the largest freshwater lake in Florida even though it has been changed somewhat by humans. Locating this lake on a map is easy!
Rivers
down rocks by physical weathering, rain falls and moves particles into the rivers by erosion and deposition. For this reason, land around rivers is often very rich in nutrients. The Everglades in Florida is a special kind of river. The water in it is exceptionally slow moving, sometimes shifting only one to two feet per day. However, it is very wide—up to 60 mi. in some places. Because the water moves, the Everglades is not considered a swamp; rather, it is a wetland, which is a unique type of habitat.
A delta body of water. As a river moves, it carries sediments like soil and small rocks. When a river meets the ocean, it slows down and the sediment is deposited, forming a delta.
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4. What are the primarybetweendifferences lakes y and rivers?
All of the landforms that have been mentioned prior to this point are found in Florida. Mountains are the largest landforms on Earth. They are created by either volcanic eruptions or plate tectonics. When push together, mountains are created as the land folds together. Each mountain usually comes to a peak. Some mountains have snow at their peaks all year because they are so tall that temperatures at the peaks do not get high enough to melt the snow. While Florida’s highest point is called Sugarloaf Mountain, at 95 m above sea level, it’s not truly a mountain
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most of your life. Glaciers are not found in Florida—now or ever before. Florida may see snow on rare occasions, but there is not enough snow or ice for it to stay on the ground and develop into a glacier. As a matter of fact, Florida was where the Paleo-Indians relocated during harsh winters in the north because of its milder temperatures.
Glaciers are large bodies of ice that do not melt away in summer because they form where temperatures stay very cold for most of the year. Because they are miles and miles in size, they move across land due to their weight, removing soil and other structures that are in their way and revealing bare rock as they pass. Glaciers can erode soil and rock and deposit them in other locations.
5. Why are the larger landforms in t hy arger rger as mountains?
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Dr. Joni Mäkinen, PhD, and Dr. Kari Kajuutti, PhD University of Turku, Finland
Joni Mäkinen and Kari Kajuutti studied landforms in Finland with the help of laser technology. They noticed something strange when they found triangular-shaped landforms that were created during the last ice age
Because these areas are covered by forests and in remote areas, they had never been noticed before. murtoo, which is a word that comes from the word for broken in Finnish. They have since discovered the same type of landforms in Sweden, which experienced the same ice age. As it turns out, when large sheets of glacial ice melted, the conditions were right for large amounts of melted ice to shape these areas.
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Earth’s surface has a variety of types of landforms. Landforms are natural formations or areas of land Other landforms are raised, such as hills, mountains, and dunes.
Many changes occur to Earth’s landforms over time. Blowing wind, moving water, and freezing ice cause weathering, erosion, and deposition that can transform Earth’s surface. For example, young mountains are tall with steep slopes. They have sharp, jagged peaks. Over time, due to wind, their slopes become less sharp. Their peaks become rounded and smooth.
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landforms would wear down less quickly over time and sand and dirt would not be carried downstream to deltas or oceans. Soil would build up in areas where it was previously eroded. This could impact soil health along river coastlines and farther downstream.
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Summarize It
1 Which landform is created by the buildup of materials that are eroded and deposited by a river?
A Lake
B Delta
C Coastline
D Dune
2 The large shapes of land that make up Earth are called–
A glaciers.
B mountains
C deltas.
D landforms.
3 Florida has all of these landforms EXCEPT–
A mountains.
B rivers.
C dunes.
D coastlines.
4 Weathering is the–
A movement of sediment from one location to another.
B breaking down of rocks and landforms
C dropping off of materials to a new location.
D changing conditions of temperature and precipitation.
5 Which of the following would be the best model of erosion by a river?
A Dropping vinegar on chalk to show how acid can break down land
B Creating puddles in dirt to show how water accumulates in a dry area
C the container
D down the ramp
6 Describe each of the landforms in the table based on characteristics that we use to recognize them
Spheres and Layers of Earth
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Imagine being a skydiver. You jump from a metal plane and free fall through the air until you are falling as fast as you can—at about 150 miles or 240 kilometers per hour. As you pull your parachute, you notice the puffy white clouds all around you and feel water vapor on your face. The air is freezing cold
How would you describe the individual parts of Earth that were part of your journey during this experience?
1. What parts of Earth does a skydiver . What parts hat part interact with when they make a jump from an airplane?
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Earth is a complex planet that has undergone constant change since its formation. From the diverse plant and animal life to the colorful rocks, the weather and climate, and the oceans and ice, our home planet truly has everything.
To help us break this massive area of study into parts, let’s consider the shape of Earth. Earth is a sphere, or a ball-shaped planet. Inside this massive sphere are smaller spheres that contain various elements that make up the planet. Scientists think of these spheres as overlapping subsystems (subice, and land.
blocks of life, create geological events, give way to Earth’s weather conditions, and showcase the biodiversity on our planet. Let’s explore each of these spheres, their components, and the interactions between the spheres.
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and the atmosphere.
The geosphere is the portion of Earth that includes hard land, rocks, and soil. It also includes the molten rock in Earth’s interior, rocks and minerals, landforms, and processes that shape Earth’s surface.
geo-, meaning “Earth.” It is uneven, stretching from the tops of mountains to the core of Earth. Earth’s geosphere is made of all the solid and molten rock, soil, and sediments of the planet. The solid portion of the planet under our feet includes dirt, mountains, and any other hard surfaces, such as continental and oceanic crust. The molten portion of the planet, which you cannot see, includes lava, magma, and the mineral compounds in the ground.
The geosphere serves as the foundation on which everything else on our planet has built habitats. It is the land that we plant crops in, the land that we mine ore from, and the materials that we use to make bricks.
The geosphere is all of the land, rocks, and soil that we see and the materials inside Earth.
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hydrosphere consists of all the water on hydro-, which means “water.” The hydrosphere includes all water in its different states—from freshwater bodies like atmosphere as water vapor, in clouds, on the surface as groundwater, falling as precipitation, and frozen at the poles.
The frozen water on Earth is part of the hydrosphere but is also given its own name. Because so much of Earth’s water is tied up in a frozen state, this is known as the cryosphere. This sphere gets its name cryo-, which means “icy cold” or “frost.” Some places on Earth are so cold that the water is frozen solid. The cryosphere is composed of areas of snow or ice that are subject to temperatures below 32°F for at least part of the year.
Ice and snow on land are part of the cryosphere. In fact, the largest parts of the cryosphere include the continental ice sheets in Greenland and Antarctica as well as ice caps, glaciers, and areas of snow and to the sea surface produces shelf ice.
The other part of the cryosphere is ice that is found in water. This includes frozen parts of the ocean, such as in the water surrounding Antarctica and the Arctic. It also includes frozen rivers and lakes, which occur mainly in polar areas.
from the Sun, helping regulate our planet’s temperature. Polar regions are some of the most sensitive to changes in climate.
Glaciers, ocean water, and clouds are all parts of the hydrosphere.
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2. What is the difference between the hydrosphere and cryosphere? hydrosphe
The fourth of Earth’s spheres, called the biosphere, is the sum of all living matter on Earth, including bio- means “life.” This includes all the plants and animals that live on Earth, including those that live in caves, rivers, deserts, and arctic regions. Organisms in six kingdoms, including fungi, bacteria, and plants, are included in the biosphere.
The biosphere has smaller parts called biomes, which contain different living organisms. Earth is divided are large landmass areas, such as the tropical rain forest (jungle), savanna (grassland), taiga, tundra,
Both this porcupine and the plant that it is eating are part of Earth’s biosphere.
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atmosphere is the thin layer of gas that surrounds and insulates our planet and is held in place by atmo-, which means “air.” The atmosphere makes life possible on Earth. Earth’s atmosphere is approximately 78% nitrogen and 21% oxygen. energy that is needed to survive. The amount of solar radiation
Earth’s surface. Earth’s surface reradiates the energy that it absorbs from the Sun as thermal energy. This thermal energy is absorbed by greenhouse gas molecules in the atmosphere, including carbon dioxide gas, further warming Earth.
The angle of the solar radiation that reaches Earth’s surface also affects the amount of solar radiation that is absorbed. At latitudes closer to the poles, solar radiation hits Earth’s surface at a low angle. This scattered) and are less intense at the surface because their energy is not as concentrated. Receiving less direct solar radiation causes the poles to be colder than the tropics, which receive more direct solar radiation. Uneven heating of the atmosphere by the Sun’s energy causes weather patterns on Earth, impacting our daily living experience.
extreme freezing temperatures every night. The troposphere begins about 12 km (approximately 7.5 mi.) above Earth. The molecules in this layer are densely packed together. The troposphere also contains evaporated water vapor and therefore is the site of atmospheric weather.
The layer directly above the troposphere is the stratosphere. The stratosphere contains the ozone layer for life on Earth, there are other forms of dangerous energy from the Sun, such as ultraviolet radiation. The ozone layer protects life from harmful radiation by absorbing ultraviolet radiation, which can cause harmful radiation would reach the surface and cause stronger effects.
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Have you ever seen a shooting star streak across the sky at night? Is it really a falling star? No. It is, however, a meteor falling toward Earth. Most meteors burn up in the mesosphere.
The fourth atmospheric layer above Earth is the thermosphere. Because it is located above the ozone layer, the temperature in this layer can reach 1,500°C. This layer is the site of the aurora borealis,
3. What would happen on Earth without the atmosphere?
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hydrosphere. It interacts with land in the geosphere by weathering and eroding rocks. The waterfall sends water droplets into the atmosphere as water vapor. There are also clouds in the image, which are a result of an interaction between the hydrosphere and atmosphere. The moss on the rock in the image is an interaction between the biosphere and the geosphere. The waterfall provides moisture to allow moss to grow on the rock.
to the air. The geosphere provides the hydrosphere with a means for bodies of water or ice that have atmosphere, helping regulate Earth’s temperature.
causes water from the ocean and other bodies of water to evaporate, moving water particles from the hydrosphere into the atmosphere. The water vapor might remain in the atmosphere as clouds or return to Earth as precipitation. Maybe one of the most important interactions of the hydrosphere is providing water to habitats in the biosphere.
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Ice from glaciers interact with the geosphere as sheets of ice from the cryosphere move and erode land.
The atmosphere, hydrosphere, and geosphere all interact as a connected system that shapes the ways that all living things in the biosphere experience daily life, weather, climate, and their environments. animals (geosphere).
hurricanes form, the atmosphere and hydrosphere work together to move the storm through the water. The atmosphere is another medium for weathering and erosion of rock.
There are many, many examples of how the spheres of Earth interact and impact one another. Studying these interactions is important to understand the world around us and what impacts we have on the spheres of Earth.
4. Give an example of at least three Give an examp spheres of Earth interacting. Be sure to name the nteracting. racting spheres and the components in the spheres that you choose.
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Dr. Ben Kirtman, MS, PhD University of Miami
Ben Kirtman is a professor at the University of Miami in Florida. He teaches graduate courses on atmospheric movements and patterns, such as El Niño and La Niña, as well as climate prediction. He is a mentor to advanced students who are studying weather and the oceans. Kirtman is also the program director for climate and environmental hazards at the Center for Computational Sciences. He investigates and researches how climate changes over various periods of time, from days to decades. Kirtman has published many research papers, including one discussing the effect of climate change on
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biosphere, and atmosphere. The geosphere is solid Earth, the hydrosphere contains all of Earth’s water, the biosphere contains all of the life on Earth, and the atmosphere involves Earth’s air resources. Each
Connect It
What spheres of Earth are involved in skydiving?
they jump through the air, the atmosphere contains the air that is all around them.
3
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Summarize It
A The hydrosphere contains water, and the atmosphere consists of air.
B The hydrosphere contains the air on Earth, and the atmosphere contains water.
C The hydrosphere contains life, and the atmosphere contains land.
D The hydrosphere contains land, and the atmosphere contains water.
A Biosphere and geosphere
B Atmosphere and biosphere
C Geosphere and atmosphere
D Atmosphere and hydrosphere
A The atmosphere protects Earth from space objects.
B The atmosphere regulates the temperature of Earth.
C The atmosphere provides the right mix of breathable air.
D The atmosphere provides fresh water for organisms
4 Fill in the table with the correct spheres that are described (geosphere, hydrosphere, cryosphere, biosphere, or atmosphere).
Name of Sphere Features
Variety of ecosystems and organisms
Solid and molten rock, soil, and sediment
Air, oxygen, and insulating layer of the planet
Ice, glaciers, and the frozen water at the poles
5 hydrosphere, cryosphere, biosphere, and atmosphere.
Influences of Weather and Climate
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1. When it snows, how are the hydrosphere and atmospherehydrosphereinvolved? a
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2. Give an example of weather and example an example of climate. n examp
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Indirect sunlight
Circle
N
Direct sunlight
N
of Cancer
Indirect sunlight
S
Circle
of Capricorn
S
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3. Which way do molecules move—
3. Which way W from areas of high pressure to those with low pressu gh press pressure, or from low pressure to high pressure? Why? w pressure to g re g
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air mass
high-pressure air mass
Warm air rises
Air sinks
Air spirals down and out
a low-pressure air mass
Air spirals upward
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4. Suppose a lowpressure air mass is north of your ressure air m state, and winds are yo h oy coming from the north. What kindt ming fro of weather would you expect in the next couple of days,t ct in and couplewhy? uple
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warm front
Warm air
Warm front
Cold air
Wind
cold front
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isobars
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June Bacon-Bercey
NOAA’s National Weather Service and US Atomic Energy Commission
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Connect It
How are the hydrosphere and atmosphere involved in snow? crystals.
Warm, moist air rises. Clouds form. In cold temperatures, water droplets supercool into ice crystals.
Ice crystals collide, grow together, and form snowflakes.
When snowflakes are large enough, they fall to Earth.
Natural Disasters
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On August 13, 2004, Hurricane Charley shocked Floridians after making a surprise turn and hitting the state. Three weeks later, on September 5, Hurricane Frances struck Florida as well. The country watched as Hurricane Ivan hit Florida’s east coast only 11 days later, on September 16, and then reorganized and crossed the southern part of the state again on September 21. A fourth storm, Hurricane Jeanne, made
weeks, these four storms caused more than $42 billion in damage and 109 deaths in Florida alone. How can places prepare for storms such as hurricanes?
Hurricanes are not the only natural disasters in Florida—despite these shocking facts about the uncommon either! Even with these potentially life-threatening hazardous weather events, Florida is still a very common place for vacation or relocation. Theme parks, beaches, and thriving cities bring many people to Florida, making the economic effects of natural disasters that much more noticeable.
1. What do you think makes some natural events so devastating?
2. Why do you think Florida still has so t Why y many tourists despite hazardous weathertourists desp events?
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Hurricanes are just one type of natural disaster that affects human life in Florida. They are considered the most dangerous because of the large area that they impact. The high winds cause major damage to buildings, and the rising water levels cause storm surges. These walls of water that come ashore cause beach erosion and destroy coastal homes and businesses. Tornadoes, heavy rains, and are all associated with hurricanes.
3. What is the cause-and-effect relationship between hurricanes, tornadoes, betwe
There are, however, many ways that Floridians can protect themselves and their businesses from approaching, citizens must monitor the weather and prepare their houses and businesses by securing windows and doors, moving loose items indoors, and having emergency supplies on hand.
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Floridians also know that thunderstorms are a common part of the state’s weather. These of Florida’s summer climate can create areas of very dry vegetation. A single spark can lead to widespread devastation.
Even though they are not as dangerous as hurricanes, thunderstorms can also bring long-term effects. winds pushing them in multiple directions. This can cause falling power lines, large-scale erosion, and irreparable damage to vehicles and buildings.
4. How are thunderstorms and hurricanes similar to each other?
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Although it does not fall into the typical category of a natural disaster, another thing that Floridians disastrous for our skin! According to the Centers for Disease Control and Prevention, skin damage can occur in as little as 15 minutes of unprotected Sun exposure you plan to be outside at any time of day.
5. What effect does overexposure to sunlight have on our unlightbodies? h ht h
Dr. Scott Braun, PhD NASA
in studying hurricanes on the inside and out by using computer models to look at details like wind, rainfall, and temperature. His work is a fundamental part of creating hurricane forecasts, so Braun is Floridians prepare for hurricanes as early as they do!
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Beyond the immediate threat to property and human safety from water and wind, natural disasters bring damage to their buildings, the repairs often take months or years to complete. In this time, employees nearby businesses. Tourist attractions, such as theme parks and cruise terminals, can be damaged and closed for periods of time, causing the people who work there to lose income. Farmers can lose their crops, leading to a range of effects on Florida’s citrus fruit industry. It’s like a domino effect of negative impacts from the original event of the natural disaster!
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impacts of hazardous weather?
In Florida, there are many thunderstorms, including those that come with hurricanes, potentially causing long-term devastation.
Weather Formation
temperature, wind, moisture, and air pressure.
one out of the way. The warmer mass has molecules that are farther apart from each other. The cooler mass’s molecules are closer together because less heat energy has reached them. This difference in density causes thunderstorms to form as the masses try to move around and past each other.
with altitude, which creates a horizontal spinning effect in the lower atmosphere, which then shifts to a vertical spin.
Hurricanes form over warm, moist water. This warm, moist air begins to rise and is then replaced with cooler air, forming a low-pressure area underneath. This causes more air to rush in, forming clouds and thunderstorms. These continue to grow and begin to rotate due to the rotation of Earth, and this is called the Coriolis effect. Once wind speeds reach 74 mph, the storm is considered a hurricane.
Floods can accompany thunderstorms, tornadoes, and hurricanes. Because Florida is at sea level and surrounded by warm ocean water, any prolonged rain from thunderstorms or hurricanes can create
2
3
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Summarize It
A Getting caught in a thunderstorm
B Being outside between the hours of 10:00 a.m. and 3:00 p.m.
C
D Taking a walk at night
One main difference between thunderstorms and hurricanes is that–
A thunderstorms happen only in winter.
B
C hail happens only during a hurricane.
D hurricanes have much higher wind speeds.
A Thunderstorm hurricane
B Flooding hurricane thunderstorm
C Flooding thunderstorm hurricane
D Hurricane thunderstorm
A
B Hurricane
C Tsunami
D Landslide
A Building a home farther inland and away from the shoreline
B
C Building on the ground level by the coast
D
6 Fill in the table below to describe each hazardous weather event.
Thermal Energy
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Our bodies have several ways to help monitor and maintain our temperature. The hypothalamus responds to signals throughout the body by regulating processes like sweat production to help us maintain a consistent body temperature when the weather is colder or warmer outside. Blood also plays a role in helping our bodies warm up or conserve heat.
If you play in the snow on a winter day and then drink a hot beverage, how does the heat warm you?
1. How does heat get from one area of a person’s bodyar et from one to another? a persons
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Whether heat is moving throughout our bodies, through the layers of Earth, from a stove to food, or across the country as an air mass, the basic principles are the same.
Small, invisible particles called molecules make up all matter and are always in motion. This is called thermal energy. Thermal energy is the total kinetic or motion energy of these particles. The faster the molecules move, the warmer the matter becomes. Thermal energy can transfer from molecule to molecule throughout a system such as the human body or the atmosphere. A system is a group of interacting, interrelated, or interdependent elements that form a complex whole. Energy can transfer within a system or from one system to another, such as from your body to the atmosphere. Energy transfer is the movement of energy from one system to another.
instance, the appliance is taking heat away from the food inside, and the absence of heat is known as cold. We can measure the temperature of the air inside the refrigerator; temperature is a measure of the motion of the particles that make up matter. Temperature measures thermal energy. The particles in all matter vibrate faster when they have more heat and slower when heat is absent. Even molecules in frozen matter are in motion.
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The temperature of matter changes when thermal energy is transferred from molecule to molecule within the matter. As the kinetic energy of the molecules increases, it can cause changes in matter’s state, such as melting or evaporation. As it decreases, it can cause matter to condense or freeze. The temperature will change as well.
2. What are some measurable or observable changes that take place whenchang servable thermal energy is transferred within a system?
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There are three main ways that energy transfers through matter. Let’s look at the two that require
Conduction is the transfer of thermal energy that occurs in solids, liquids, and gases when two substances of different temperatures are in direct contact. This happens when two substances touch, and matter must be present for the heat transfer to take place. Heat transfers from particle to particle is transferred.
Let’s examine how this occurs on the molecular level.
Metal rod
Thermal energy flow
Thermal energy is applied to the molecules in the metal rod from the candle on the left. The candle is a energy to the system of molecules in the metal rod. So, this is an example of an energy transfer between two separate systems.
As the molecules on the left side of the metal rod are heated, they begin to move faster. As they do, some of their thermal energy is transferred down the rod and to other molecules that are farther away from the heat source. This causes the temperature in those molecules to increase. Eventually, the entire metal rod would become hot to the touch if thermal energy continues to transfer.
Another example of conduction is within Earth. Heat is generated in the core and transferred through conduction from the outer core to the mantle.
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is a similar process, but it occurs mostly in liquids and gases. It is caused by the rising of energy transfer. However, the matter could be in the form of a gas, such as air in the atmosphere. Look at the diagram of a lava lamp.
Cool
Fluids warm, expand, and rise.
Fluids cool, contract, and sink.
Warm
a n l m nt trans rs t rmal n r to uids.
A lava lamp is a closed system that uses heat that is generated from a bulb or heating element at the blobs of wax to expand, condense, and move.
Convection is the process that allows your furnace or heater to heat the air or allows your air conditioner
conduction from the outer core. As the material in the mantle heats up, it rises and moves horizontally. Once it begins to cool, it sinks back down. This is conduction occurring within the layers of Earth.
Weather changes come from convection in the atmosphere as heat is transferred between air masses and from the ocean to the air. The reason why thunderstorms most often form on summer afternoons involves thermal energy transfer. The Sun heats the ground and the atmosphere throughout the day, and when this thermal energy is transferred through the air, it causes molecules of water vapor to rise. They cool as they reach higher altitudes, causing the molecules to move back toward the ground. Eventually, this circular movement contributes to cloud formation and growth and causes wind. This is an example of thermal energy transfer via convection within a system.
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Billowing storm clouds like these are formed from strong convection currents in the atmosphere, which are caused by thermal energy transfer from the ground through the water vapor in the atmosphere.
Other places where we see convection are in the movement of water inside a pot, in food heating in ovens, in the formation of thermal air currents in the atmosphere, and ocean currents.
transferring to another area. This keeps homes warmer in winter and keeps heat out in summer. In this way, insulation in walls and attics prevents thermal energy transfer via convection inside the home
3. Describe how thermal energy is transferred through mal a heated ransferredaquarium. throg nsferred Indicate how energyaquariu enters the system ndicate cate how and how it circulates syst nters sy within it.
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The third kind of thermal energy transfer does not require matter. This is radiation. Radiation is the transfer of energy by the movement of electromagnetic waves or subatomic particles. Although matter is not required for radiation to take place, radiation can work through matter.
ones do. These are important factors to consider when determining how radiation can enter or leave a system.
Examples of radiation include the Sun’s heat, which must travel through space. When thermal energy is released from an incandescent light bulb or from a room’s space heater, these are both examples of thermal energy transfer through radiation. When the Sun’s energy traverses space to reach Earth, radiation is the method of thermal energy transfer at work. Thermal energy leaves Earth’s system through radiation as well, through heat being radiated back out into space. Ultraviolet radiation from the Sun is dangerous to humans. Too much sunlight can cause a sunburn. It is important for humans to remember to cover up and use sunscreen to protect themselves from too much Sun exposure.
How powerful is radiation? According to the University of Oregon, Earth receives an average of 164 watts per square meter over a 24-hour period. This means that the planet as a whole receives 84 terawatts of power from the Sun’s radiation alone. Worldwide power consumption is only about 12 terawatts per day. Therefore, Earth receives a tremendous amount of thermal energy transfer
4. How is radiation different from conduction and convection?
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You may have noticed a pattern in the examples of conduction, convection, and radiation. Thermal energy always transfers from an area that is warmer to one that is cooler. This thermal energy transfer continues between two objects until both reach equilibrium. Equilibrium is a condition in which all when both reach the same temperature.
5. Does thermal energy move in a predictable pattern? ergy m If so, describe it. redictable patte edic
Dr. Won Jun Choi, PhD Korea Institute of Science and Technology (KIST)
Won Jun Choi is a researcher at the Korea Institute of Science and Technology, where he leads a research team that is investigating technology for sensing thermal energy using a smartphone. The thermal energy sensor that they are developing allows a smartphone user to check temperature in real work at cooler temperatures and use less electricity. also known as solar cells.
measure temperature in real time using a smartphone.
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Thermal energy is transferred between and within systems in three ways: conduction, convection, and radiation. Thermal energy is the total kinetic or motion energy of molecules within matter, which is required for energy transfers that involve conduction and convection. Conduction is a method of heat transfer that involves two objects or surfaces that are in contact with one another. As molecules vibrate in place, thermal energy is transferred from the warmer object to the cooler one. In convection, a similar for radiation.
Connect It
How does thermal energy transfer within and out of the body?
Thermal energy is generated by the body through normal metabolic processes and then is transferred in several ways. One method is through the blood. Because blood is a liquid, convection is the process by which this occurs inside our blood vessels. If your warm body is in contact with a cooler surface, such as a chair, conduction carries thermal energy out of your body to the other surface until both reach equilibrium. Our bodies also radiate thermal energy through our skin, and as moving air around us passes over our skin, convection transfers body heat out to the air surrounding us.
This is an image of a human as seen with thermal energy. The red area may show thermal energy blue color on the image as it releases heat from the body.
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We have learned the three ways that heat is transferred: conduction, convection, and radiation. Along with this heat transfer, changes in temperature occur. A change in temperature can cause a change in increases, a substance melts, resulting in a liquid. As the temperature continues to increase, a liquid changes into a gas. This is because the kinetic energy of the atoms decreases and increases as temperature decreases and increases. Less thermal energy results in less kinetic energy. As thermal energy increases, kinetic energy also increases.
State Changes of Water
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Summarize It
1 How does the motion of molecules in solids relate to thermal energy transfer in conduction?
A As molecules gain thermal energy, they begin to move around and transfer thermal energy to the molecules that they pass by.
B neighboring molecules at a cooler temperature
C energy.
D transferring it to less-active molecules nearby.
2 A student conducts an investigation in which they heat water on a hot plate. Which of the following answers explains the results that they may get from this investigation?
A Thermal energy transfers from warmer molecules to cooler ones in the water via convection.
B Thermal energy travels through the cooler molecules in the water to warmer ones after contacting the hot plate.
C The water will heat up faster if the Sun is shining because radiation conducts thermal energy.
D Conduction allows the cooler molecules to transfer heat energy to warmer molecules
3 A microwave heating leftovers is an example of thermal energy transfer by–
A radiation.
B induction.
C convection.
D conduction.
4 Fill in the blanks in the table with the correct method of thermal energy transfer: conduction, convection, or radiation.
Method of Thermal Energy Transfer
Example
Thermal energy transfers from a warmer surface to a cooler one when the surfaces are in direct contact.
Thermal energy is transferred through space to a habitable planet.
A hurricane forms when the Sun heats the surface of the ocean.
Warmer air rises, and cooler air falls.
Distance-Time Graphs
Motocross is a sport involving motorcycles that race over high hills and steep valleys. Competitors in
1. How could we graph the distance and timet we grap of a motocross racerthethroughout race? er throug
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-4-3-2-1 0 1234 distance-time graph x-axis y-axis
2. What information is graphed on the x-axis of agraph?distance-time informationWhat is graph? W graphed on thephedy-axis?
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Speed is the rate of change of
3. When interpreting the motion of an interpretingobject t terpreting using a distance-time obje graph, how can you sing distance tell the difference y ho between constant speed and variable speed of an object?variab d and variab
Earl Lucas Ford Motor Company
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Connect It
How could we graph the motion of a motocross racer? in it as the motocross racers themselves!
Forces on Objects
Think about the last time that you bounced a ball on the ground. As the ball left your hands, it fell toward the ground because of gravity. However, gravity was not the only force at work on the ball. Several forces were acting on it. What are all of the forces that acted on the ball?
1. What forces act on a basketball in motion as it bounces
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A force is a push or pull that can change the motion of an object. Because a force involves a push or pull, it involves two objects. One object must interact with another object for a force to occur. All objects, living and nonliving, can exert a force on other objects, and all objects can be affected by forces.
There are two kinds of forces. Contact force results when two objects are physically in contact with each they touch it. This is a contact force.
The other kind of force is noncontact force, which works on objects that are not physically in contact with each other. The force of gravity is a noncontact force; it acts between two celestial bodies that are not physically in contact with one another, such as the Moon and Earth.
Types of Forces
Forces are measured in units called newtons (N). The larger the number of newtons, the stronger the force is.
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You are likely familiar with the force of gravity. Gravity is a noncontact force that causes objects with mass to attract one another. Newton’s law of gravity states that any particle of matter in the entire universe attracts every other particle through gravity. The strength of the gravitational force depends on the masses of the objects and their distance from one another. Objects with large masses have stronger gravity; for instance, the Sun has the largest force of gravity in the solar system because it is by far the object with the most mass.
Although the Moon and Earth are farther from the Sun than Mercury is, the Sun’s gravity still exerts a force on both. The reason why the Moon orbits Earth and not the Sun, however, is related to distance. Earth is much closer to the Moon than the Sun is, so it exerts a stronger gravitational force on the Moon than the Sun does. However, because Earth orbits the Sun, it pulls the Moon along with it. Objects that are closer to each other have a stronger force of gravity than two objects that are farther apart.
2. What would be the two characteristics of any object
that
would cause it to exert the strongest gravitational force possible on rongest gravita g another object? orce possible
Gravity is exerted on every object on Earth. If you throw a ball into the air, gravity will act on the ball to pull it toward the ground.
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An example of a contact force is friction, which is created by two surfaces in contact. Friction is a force of friction is minimal. The rubber soles on shoes are there to increase the force of friction and allow you happens than when friction is weaker.
Friction depends on the surfaces that are in contact. For example, an ice skater on ice is able to skate because the ice does exert friction, but it is not strong enough to completely oppose their forward motion. Because the skater’s applied force is greater than the force of friction, they will continue to move forward around the rink. Friction will eventually cause them to slow down
Friction is a force that opposes motion. In this case, the friction that is created by an ice skater’s skate on ice opposes their forward motion, causing them to slow down as they skate.
You have experienced friction in your life. For example, when you squeeze the brakes on a bicycle or apply pressure to the pedals, the brake pads on the bike apply a force that creates friction on the wheel of your bicycle. This frictional force opposes the motion of your bike tires and causes you to slow down or stop. If you have ever walked against the wind, you have felt the force of friction opposing your motion.
3. Describe a situation where friction is at work. Be sure to explain the two surfaces Be sure to exp that are in contact with each other and the effect of friction on motion in your situation.
Forward motion of the skater
Friction opposing the skater ’s forward motion
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Another familiar force is magnetism. Magnetism is a noncontact force between atoms that have opposite charges. Have you ever heard the phrase “opposites attract”? This refers to the charges between oppositely charged particles—in other words, magnetism.
The force of magnetism is seen in many places in everyday life, such as electromagnets, computers, car motors, and refrigerator magnets. The strength of a magnetic force depends somewhat on distance; objects that are farther away from each other will have a weaker attractive force than those that are close together. You feel this if you take two magnets and hold the oppositely charged poles a short distance apart. The closer you move them together, the more strongly attracted they are.
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the clothing sticks together. When you pull the clothes apart, you may hear a crackling sound. These events occur because of electrical force.
Electrical force is an example of noncontact force. Rubbing materials together, like your socks on the another. Similar to magnetism, like charges repel each other and unlike charges attract each other. Building up one type of charge on an object can cause it to “jump” to another object, creating the zap on
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An applied force is a force that is applied to an object by another object. Any object, regardless of whether it is living or nonliving, can exert an applied force on another object. For example, the wind can push a kite along in the sky on a windy day. A screwdriver or a pair of pliers applies force to a screw or to another object to make it move. Almost any time two objects are in contact with one another, a force is being applied.
Tools like these apply a force to objects like nails, screws, nuts, and bolts to make them move.
4. Describe an example of an applied force at p school. Identify pplied orc the object that is applying the force t and the object pplying the ng the that has the forceobje acting on it.
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Normal Force
Have you ever wondered why gravity does not just pull an object straight down to the center of Earth? It is because of the normal force. The normal force is the force that is generated by a surface in opposition to an object that is pressed upon it. Just like frictional forces oppose motion, normal forces oppose the force of an object pressing down toward the center of Earth.
table, remains at rest on that surface instead of falling to the center of Earth. It is a contact force, so it only affects objects that are in contact with other objects.
Fgravity
Fnormal
The normal force works in opposition to gravity and helps keep objects at rest and not falling toward the center of Earth.
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Forces do not work in isolation. Forces are always paired. An applied force is usually opposed by some kind of friction. Gravity is always opposed by the normal force. Because forces work in pairs, they can be unbalanced or balanced, and this determines whether the object will move, continue moving, change speed or direction, or stop.
We can use force diagrams to show how forces interact with one another and work on objects. For most objects, there are at least two forces at work, but more commonly, there are four. Let’s examine this force diagram to describe how the forces are at work.
The image shows four forces at work on a lawn mower. Gravity attracts the lawn mower toward the center of Earth and is opposed by the normal force, which prevents the mower from sinking through the grass. The person is applying a force in a forward direction as they push the lawn mower. The force of friction acts on the mower’s wheels to oppose their forward motion.
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Richard T. James, Inventor of the Slinky United States Navy
Richard T. James was a mechanical engineer in the United States Navy and accidentally invented the springs. As he dropped one and noticed the way it moved, he wondered if the forces at work in the spring could be used in a children’s toy for entertainment.
After producing and demonstrating the toys in stores in December 1945, James’s Slinky became extremely popular and remains so today. A special marker in Clifton Heights, Pennsylvania, where James developed his invention, notes the achievement.
According to the Smithsonian Institution, James described the Slinky in its patent as “a helical spring toy which will walk on an amusement platform such as an inclined plane or set of steps from a starting point to successive lower landing points without application of external force beyond the starting force and the action of gravity.”
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Forces act on all objects and usually are exerted in pairs. Gravity pulls an object toward the center of Earth, and the normal force opposes that motion and prevents the object from falling toward Earth. Applied forces come in many forms but are usually pushes or pulls exerted on an object. When two surfaces are in contact and motion is opposed, friction is at work. Magnetism is a force that is generated by oppositely charged atoms and works to attract or repel objects depending on their charges.
Connect It
What forces are at work on a toy truck as a child plays?
As a child plays with a toy truck, a force is applied when the child pushes or pulls. Gravity is always exerted on the truck, pulling it toward the center of Earth. Normal forces counteract the force of gravity and prevent the truck from falling to the center of Earth. Friction is at work any time the truck is in contact with another surface, and this force will oppose its motion.
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Summarize It
1 that are acting in this situation?
A
B The force at work is magnetism, which is a noncontact force.
C Gravity and the normal force are the only two forces at work in this situation
D
2 Which of the following is NOT an example of an applied force?
A A dog pulls on its leash during a neighborhood walk.
B A billiard ball hits another billiard ball during a game.
C
D Jupiter exerts a force on the asteroids in the asteroid belt.
3 Students climb ropes in PE class. Afterward, they discuss the forces that are acting on them.
• Jay says, “Gravity was at work on both me and the rope, attracting us to Earth.”
• Armani says, “Friction was acting on my hands as I climbed the rope.”
•
• Stephanie says, “I applied a force to the wall when I put my feet on it to balance myself.”
Which student(s) gave a correct statement about the forces that are at work in this scenario?
A Jay, Armani, and Stephanie
B All four students
C Armani, Jon, and Stephanie
D Jon only
4 As a young plant germinates and grows in soil, which of the following describes the forces that are exerted?
A Earth’s magnetism opposes gravity and helps the young plant grow upward.
B The roots pull down on the stem of the plant because of the normal force
C The plant applies a force to the soil as it germinates and grows, and the soil applies slight friction to the plant.
D The plant grows toward the Sun because of the Sun’s gravity.
5 different forces that are being exerted in this situation.
Net Force
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You probably played with toy cars when you were younger. Maybe you made up situations in your head as you pushed or pulled the car along imaginary streets.
As you grew, your interests may have changed to remote control vehicles or perhaps a bicycle of your own. In just a few years, you will be licensed to drive a car, truck, or motorcycle. How do forces make these vehicles go, stop, or change direction? Are the forces at work on each of these vehicles similar? How can these forces be measured or calculated?
1. How do forces make a toy truck stop, go, or direction?change go, or
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A force is a push or pull that can change the motion of an object. Forces can only occur as the result of an interaction between two objects, such as a push or pull.
There are two main categories of forces: those that result from objects in contact, and forces resulting from objects that are not in contact with each other.
Types of Forces
Forces work in pairs as they are exerted on an object. For example, gravity might pull an object on a table downward, but normal forces push up. This is why the object doesn’t sink or fall toward the center of Earth. A book on a table may not move, but it is acted upon by two opposing forces—gravity pulling down and normal force pushing up.
The books at rest on this table have two opposing forces acting on them, even though they are not moving. Gravity pulls the books toward the center of Earth while the normal force holds them up.
We show forces and the directions in which they act on objects by using arrows on diagrams. The strength of a force, also called its magnitude, is measured in newtons (N). The larger the number, the stronger the force.
2. What do the arrows on a net force diagram tell us? diagr
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When a force pair is balanced, the object acted upon by the forces will not move. Balanced forces are forces on an object that do not cause a change in motion. Here is an example of how this could be shown using a diagram.
The blue arrow shows the force of 70 newtons to the left. There is an equal force of 70 newtons to the right. We see this with the red arrow. Since the forces in both directions are equal, they balance each other out.
When two forces on an object are balanced, there is no change in movement. So, either the object stays at rest, if it is at rest, or it keeps moving at the same speed and in the same direction without changing. A direction is a straight path along which an object can move.
350 N 350 N
Two dogs are pulling on a bone, each with a force of 350 N. Although the bone has forces acting on it in both directions, it will not move because both forces have the same strength and are equal.
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two pairs of opposing forces acting on the objects. Accurate diagrams show both pairs of forces because they are at work simultaneously.
3. If an object is moving and the j forces acting on it t are balanced, what es acting o will happen to the object’s movement? th Will it change or bject’s moveme stay the same?
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Much of the time, however, the forces acting on an object are not balanced. This means that when opposite forces are acting on an object, they are not completely canceling each other out. There will be a difference between the two forces. If there is a remaining force when comparing opposite forces, we say there is a net force.
Unbalanced forces happen when one of the forces in the pair is stronger than the other. They can cause a change in an object’s motion. This means the object could start moving, stop, or change direction. The object will move in the direction of the greatest force.
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To calculate net force, we compare the amounts of each force acting on the object. We use subtraction to compare two opposing forces when determining whether an object has a net force. A net force is the sum of all the forces acting on an object.
The difference is zero, meaning that there is no net force.
In the second example, the force applied from the left has a magnitude, or strength, of 13 N. We will compare it to the force applied from the right of 3 N. There is a difference of 10 N, so there is a net force of 10 N. The object will move in the direction of the net force—in this case, to the right
8 N + 8 N is 16 N, that is the force being applied from the left. Since the opposing force from the right is
These forces are equal and opposite. There is a net force of zero.
These forces are unequal and opposite. There will be a net force.
These forces are unequal and opposite. There will be a net force.
Horizontal and vertical forces are often at work at the same time. Horizontal forces are those that act on an object from left to right. Vertical forces act on objects from up and down, or above and below.
horizontal one?
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60 N
150 N 202 N
60 N
vertical net force.
actually a force being applied from the right. Since it is greater than its opposing force, the net force will be in this direction, and the object will move to the left.
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4. Calculate the vertical net force and the horizontal net force for this diagram and tell which way the object g will move due to yjthe y net force.
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Friction is a force that opposes a push or pull coming from the opposite direction. If the friction is a weak force, it will not cancel out the motion, and the object will move forward despite it. Think about a soccer ball. If it is kicked with a force of 50 N from the left, and friction only exerts a force of 3 N from the right, the ball will move forward. However, if another player kicks the ball back in the same direction with the same amount of force, the forces are balanced, resulting in no net force, and the ball will not move.
N 3 N (frictional force)
N50 N
In the left image, one player kicks the ball with a force of 50 N. The friction created by the ball and the grass counteracts the 50 N force with an opposing force of 3 N. There is a net balanced, so the ball will not move. Two players both apply an equal and opposite force to the ball with a force of 50 N. Since these forces are the same, when we subtract them, there is no net force.
Roger E. Broggie
The Walt Disney Company
career as a machinist. In later years, he used his knowledge of forces to supervise the installation of
He helped create many models, including a nine-inch-tall animatronic man who could dance and sing.
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Forces act on all objects. They can be either unbalanced or balanced. Unbalanced forces are those which cause a change in motion, such as making a truck stop, move, or change direction. Balanced forces do not cause a change in motion. To calculate the net force acting on an object, simply subtract the magnitudes of the two opposing forces. The difference is the net force. If it is zero and the object is in motion, then the object will continue its current motion. If the object is at rest, then it will stay at rest.
Connect It
Are all forces on all objects similar?
Yes and no. All forces are either pushes or pulls. They act in pairs, so all forces are similar in that way Some forces are stronger in magnitude than others. For example, a hard push is much stronger in magnitude than a soft tap. All unbalanced force pairs are the same because they cause a change in motion. All balanced forces will cancel each other out, causing no change in movement.
The red ball on the left will apply a force to the other suspended balls. This will create unbalanced forces, which will cause the ball on the other side to move.
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1 What is the difference between unbalanced forces and net force?
A Unbalanced forces do not cause an object to change its motion, but net force does.
B Nothing; unbalanced and net forces are the same.
C Net forces result in unbalanced forces that make an object change its motion.
D Unbalanced forces result in a net force that will make an object have a change in motion.
A Subtract all four net forces; the difference is the net force acting on the object.
B Subtract the two greatest forces from the two smallest forces; the difference is the net force.
C Subtract the magnitudes of the opposite forces; the difference is the net force.
D Add the magnitudes of the opposing forces; the sum is the net force.
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4 Which of the following situations would not result in a change of motion?
A Unbalanced forces in more than one direction
B Unbalanced forces horizontally but not vertically
C Balanced forces horizontally but not vertically
D Balanced forces in both directions, horizontally and vertically
5
showing horizontal forces and two arrows showing vertical forces. The vertical forces should be balanced. Show an equation to calculate the net forces in both horizontal and vertical directions acting on your object.
Kinetic and Potential Energies
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Have you ever played with a Newton’s cradle? A Newton’s cradle consists of a series of pendulums spheres hanging from strings or wire. When one pendulum is pulled back and released, it hits the pendulum next to it, sending a force through the stationary pendulums that pushes the last pendulum forward. How does the energy of one pendulum affect the remaining pendulums?
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Everything in our world has energy. A car driving down the street, a basketball bouncing on a court, and a bicycle that is locked to a bike rack all have energy. How can this be? Whether an object is moving or sitting still, it has some form of energy.
Energy can take many forms. What do these forms have in common? They all have the ability to cause changes to a system, or a set of connected things that work together. As the spheres hang from strings in a Newton’s cradle, the spheres and strings together form a system.
1. Name two examples of systems that ame two exap are made of partsth te working together.
Two Types of Energy
There are two main forms of energy in a system: potential and kinetic. Potential energy (PE) is stored energy. Kinetic energy (KE) is energy in the form of motion. The total amount of potential energy and kinetic energy in a system is known as mechanical energy.
Think about a pendulum. When the pendulum swings all the way backward, it pauses for a moment. At this moment, the pendulum has only potential energy. The pendulum then falls forward, gradually gaining speed. As it falls, its potential energy changes to kinetic energy. At its lowest point, the pendulum has only kinetic energy. As the pendulum continues forward, it gradually slows down. Its kinetic energy changes back to potential energy until it reaches the farthest point in its arc. Here, the pendulum pauses again for a moment. At this moment, the pendulum has only potential energy. It then falls backward through its arc. Its potential energy changes to kinetic energy, and the cycle is repeated.
2. Name one example of an object that has kinetic energy and h one example of netic energy gy an object that has potential energy. n
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Kinetic energy is the energy that an object has because of its motion. The kinetic energy of an object depends on the mass of the object and/or its speed. Objects with more mass have more kinetic energy than objects with less mass. Likewise, objects that travel with greater speed have more kinetic energy than objects that travel with less speed.
For example, each person in a family of four will have differing amounts of kinetic energy when sledding down a snowy hill. The inner tube that is carrying a single adult will have less mass than the inner tube that is carrying an adult and a child; therefore, the inner tube that is carrying one adult will have less kinetic energy. However, the inner tube that is carrying a single adult will have more mass than the inner tube that is carrying one child; therefore, the inner tube that is carrying the single adult will have more kinetic energy than the inner tube that is carrying the single child.
Speed also affects the kinetic energy of the sledders. Imagine that the single adult’s sled hits an icy patch of snow. Suddenly, their speed increases and becomes greater than the speeds of the other sledders. In that case, their kinetic energy becomes greater than the kinetic energy of the others.
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Potential energy depends on gravity. The higher an object is, the more potential energy the object has. The force of gravity is stronger on an apple that is high in a tree than on an apple that is low in a tree. So, the higher apple will have greater potential energy than the lower apple. This is known as gravitational potential energy.
Mass also affects gravitational potential energy. Two objects of different masses that are sitting at the same height above the ground will have different amounts of gravitational potential energy. The object with the greater mass will have more potential energy than the object with less mass will have.
3. Give an example of two objects that have different amounts of ha j gravitational potential energy and explainpoten pot why the amounts nergy exp ergy p are different. hy amo h
Imagine two birds of the same size sitting beside each other on a tree branch. Their gravitational potential energy would be the same. Their mass is the same, and they are each the same distance from the ground.
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than the other, the bird at the greater height would have greater gravitational potential energy.
Finally, imagine seeing various species of birds sitting on an electric wire, all the same distance from the ground. The birds with greater masses would have greater gravitational potential energy than their smaller feathered friends.
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on a light bulb? How do you get energy from the foods that you eat? Gasoline, batteries, and food all contain chemical potential energy.
Chemical potential energy is energy that is stored in some substances because of their chemical bonds. It is energy that is stored in chemicals.
The strength of a chemical’s potential energy has to do with the strength of its bonds. Interestingly, stronger bonds have less chemical potential energy, and weaker bonds have more chemical potential energy.
The chemicals in gasoline contain large amounts of chemical potential energy. That energy is released as the gasoline is burned in a car’s engine. The release of the chemical energy transforms it into mechanical energy, making the car move.
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If you have ever held a rubber band, you have probably held it in the way that is pictured below, between two hands with one hand pulling one end of the band backward. Some objects have a type of energy called elastic potential energy as a result of their compressing or stretching. Rubber bands, springs, and trampolines all have elastic potential energy.
The amount of elastic potential energy that an object has depends on the material that it is made of and the amount of pressure or strain that is applied to the object. The more an elastic band stretches, the more elastic potential energy it has. A spring that is made of a stronger metal may have more elastic potential energy than a spring that is made of a weaker metal. Likewise, a spring that is compressed more would have greater elastic potential energy than a spring that is compressed less. In all of these examples, energy is released when the elastic material returns to its original position.
4. How are chemical potential energy and elastic potential otential energy alike? d pot
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Everything in our world has energy. Kinetic energy (KE) and potential energy (PE) may be present separately or together depending on the position and motion of a system. When a system has more kinetic energy, it has less potential energy. When a system has less kinetic energy, it has more potential energy.
Energy cannot be created or destroyed; it can only be converted from one form to another. The total energy of a system remains the same. This is the law of conservation of energy. So, within a system, as the kinetic energy increases, the potential energy decreases. When the kinetic energy decreases, the potential energy increases.
While riding your bike up a hill, you and the bike have KE. As you reach the top of the hill, your KE decreases and your PE increases. At the top of the hill, your PE is at its greatest point. As you ride back down the hill, your PE decreases and your KE increases. Your KE is greatest at the bottom of the hill.
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Melony Mahaarachchi Engineer at SpaceX
Melony Mahaarachchi is a mechanical, robotics, and rocket engineer. She came to the United States with her husband and two young children from Sri Lanka. A graduate of UCLA with a degree in aerospace engineering, she has worked at SpaceX, Boeing, and NASA in the Jet Propulsion Laboratory (JPL), including working on the Mars Rover 2020 mission. At SpaceX, Melony worked closely with Elon Musk and the Merlin engine design team on the Falcon 9 rocket. With a passion for empowering young women in science, technology, engineering, and math (STEM), Melony founded iSTEM Without Borders to support women in pursuing STEM careers.
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All matter has energy. Matter can have kinetic energy, which is the energy that an object has when it is moving, and it can have potential energy, which is the energy that an object has because of its position or condition. Kinetic energy depends on the mass and speed of an object. An object with greater mass has more kinetic energy than an object with less mass. Also, an object that is moving at a greater speed has more kinetic energy than an object that is moving at a slower speed. Potential energy comes in three forms: gravitational, chemical, and elastic. Gravitational potential energy has to do with an object’s distance from the ground. The higher off the ground that an object is, the more gravitational potential energy the object has. Also, an object with greater mass has more gravitational potential energy than an object with less mass. Chemical potential energy is stored energy in things like gasoline, food, and batteries. The energy is stored until it is used. Elastic potential energy is the energy of elastic materials, like springs and rubber bands. Compressing or stretching objects with elastic potential energy increases their potential energy. An object’s kinetic or potential energy can transfer, one to the other, so an object can lose kinetic energy and gain potential energy and vice versa.
Connect It
Where do we experience kinetic energy and potential energy?
Kinetic and potential energy are evident everywhere. From a swing set on a playground to a rollerobject’s total energy is never lost and is evident in models like a Newton’s cradle, where the potential energy of a pendulum that is about to be released transfers to kinetic energy to move the pendulum at the other end.
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Summarize It
1 Which of the following represents only kinetic energy?
A A roller-coaster car at the top of a hill
B A skateboarder at the bottom of a hill
C A bicycle moving halfway down a hill
D A ball sitting on a playground
2 Which of the following represents potential energy?
A Air leaking from a balloon
B A cat jumping onto a table
C A bird perched on a tree branch
D
3 As a snowball rolls down a hill, how do its potential energy and kinetic energy change?
A Potential energy decreases, and kinetic energy increases.
B Potential and kinetic energy both increase.
C Potential energy increases, and kinetic energy decreases.
D Potential and kinetic energy remain the same
4 Describe the conversion from potential to kinetic energy or from kinetic to potential energy as a toy car rolls down a ramp.
5 Give two examples of kinetic energy and two examples of potential energy. Explain your answers.
Cell Theory
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Every child has bumps, bruises, and scrapes from daily activities. Sometimes kids break bones in accidents. Have you ever thought about what happens deep inside a cast or under a bandage following an injury? We know that our bones and skin heal, but how does this happen?
1. Do any of our organs regenerate, and if so, how do rgans regener ns regene they do it?
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Micrographia, drawings and illustrations. Hooke coined the word cell as he discussed a cork cell’s appearance under a microscope. He noted that a cell reminded him of the rooms, which were called cells, that monks lived in at monasteries.
An engraving in Robert Hooke’s book Micrographia, published in 1665, shows his microscope. A cell is the basic structural and functional unit of living organisms. Hooke’s book ignited interest in microscopes and attracted the attention of another scientist named Antonie van Leeuwenhoek. Van Leeuwenhoek made his own single-lens microscopes, reportedly using the techniques Hooke had was able to verify Hooke’s ideas because his microscopes were able to see these organisms in more Van Leeuwenhoek’s research was very advanced for its time. After he made several observations of scientists to observe those microorganisms again.
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2. RobertscientistDescribe contributionHooke’s to cell theory.
cell theory. Cell theory has three main ideas:
• All life is made up of cells.
• Cells are the fundamental units of life.
• All cells come from preexisting cells.
organisms, or self-contained living things, that were shared between both the plant and animal kingdoms. After a collaboration, Schleiden published an article where he discussed how he thought cells were involved in plant growth and development.
Both Schleiden and Schwann used microscopes to study cells in plants and animals. Schleiden suggested that the cell was the basic expression of a plant, and therefore needed to be studied as the foundation for plants.
Schleiden thought cells were involved in plant growth and development, and this idea was part of the developing cell theory.
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structure of something is the arrangement of parts that form a living thing. Schleiden shared with Schwann his idea that all plant cells share a common structure and that new cells form from the nuclei scientists at the time believed that cells could form on their own. Schwann published a book in which he proposed that all living things are made of cells and that animal of cell theory. cell theory made sense but refuted some of Schleiden and Schwann’s claims about how cells form. He
3. How did Schleiden and Schwann expand on the basic ideas nd exp Hooke developed?
Because of these scientists’ and others’ contributions, we know today that all organisms are made of one or more cells. Some are made of a single cell, such as protozoa and protists. Larger and more complex necessary for life because they carry out vital processes such as respiration and getting rid of waste. Cells perform many functions for organisms. A function is what something does. generate, as many early scientists thought. New cells can only come from old cells.
a process accomplished by cell division.
4. What are the three main ideas that make up cell theory? t p
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As the years have gone by, scientists and others have improved microscope design and cell observation
Cell theory has continued to develop over the last several decades, and three additions have led to the development of modern cell theory.
the organism, the chemical composition is similar in all organisms. All cells are made of water, organic and water are transformed into other things as the cell performs processes like cellular respiration and photosynthesis.
Processes that are important for life, such as photosynthesis and cellular respiration, take place inside the cells of a plant.
5. How changeshave technologyin nges in ge chnology development of cell theory? elopment
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Even though the history of cell theory goes back hundreds of years, the ideas are very relevant today. Cell theory is a basic principle in the study of biology, helping us understand what living things are and how they conduct processes important to life. Cell theory helps us understand life, growth, and even
We can understand how diseases affect organisms by studying how the cells change as they are affected healthy again. Finally, it helps scientists manage diseases because they can study various treatments and their effectiveness.
Concepts of cell theory can help scientists study and manage diseases like sickle cell anemia, which causes deformation of blood cells as shown here.
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Feng Zhang Massachusetts Institute of Technology
Feng Zhang is a molecular biologist working on technology for studying the brain at the cellular level. He created genome editing tools for eukaryotic cells—including human cells—from natural systems. Zhang studies the genes that are involved in human diseases, especially disorders involving the brain. He and his team have also created special tools for scientists to use as they study immune disorders and cancer. Eventually, his goal is to develop new treatments for diseases that occur in cells.
A scientist performs research on cancer cells.
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Cell theory has three main ideas: all life is made up of cells, cells are the fundamental units of life, and disease, and death.
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Do human organs regenerate, and if so, how?
Believe it or not, one human organ can actually regenerate. Regeneration is regrowing or replacing a by cell division. By studying how cells generate from other cells, we understand how they divide and which results in a young organism changing into an adult. Broken bones and skin abrasions also heal from cell division, as new cells are formed from older cells.
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into several periods. Cell division takes place during mitosis, and the rest of the cycle is called interphase. and development stages.
• cell grows larger, makes new proteins, and develops organelles.
•
• base pairing.
• prepares for mitosis by producing the structures that are needed for the upcoming division.
• Mitosis: Although it is the shortest phase of the cell cycle, mitosis is a time of great activity. can be seen below.
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numbers during asexual reproduction? Only eukaryotic cells perform the stages of the cell cycle, including mitosis. Mitosis is important in creating exact copies so that offspring in asexual reproduction are genetically identical.
forming two identical cells. Mitosis is important in creating exact copies so that offspring in asexual reproduction are genetically identical.
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Summarize It
1 How can an understanding of modern cell theory help scientists?
2 Which of the following statements correctly describes cells?
preexisting cells.
3 Why is the cell called a cell?
A Cellular phones and other forms of technology consist of cells.
B cell means to contain, and all cells contain nuclei.
C Scientist Robert Hooke thought they looked like cells that monks inhabited.
D Scientist Antonie van Leeuwenhoek thought they looked like jail cells.
4 Cell theory consists of three parts. Which of the following would correctly complete the table?
Cell Theory
Organisms are made of one or more cells.
Cells come from preexisting cells.
A Cells are so small that they can only be seen under a microscope.
B Cells are the basic units of structure and function of life.
C Cells can be described by whether they have nuclei.
D Both plants and animals are living things with cells
Cellular Processes
Cells are so small that we need a microscope to see them. An average human body contains approximately 100 trillion cells!
1. Do the cells that make up an organism have any kind of organismorganization, rganism hav or does each cell nd organiza organiz simply “do its own thing” without regard o to other cells? ng” without rg g”
All the parts of an organism’s body, at every level, must be in a balanced, healthy state to survive and function properly. This balanced state is known as homeostasis. Organisms have levels of biological organization. At the simplest level is the cell. While cells are by no means “simple,” they are the most basic building blocks of an organism. Cells of the same type join together to create tissues. Tissues form organs. Organs make up organ systems. Organ systems work together to help an organism function. Without homeostasis, a cell is not able to do its job properly. If cells are unhealthy, organ systems cannot function, and the organism eventually dies. In other words, cells that are not in homeostasis lead to tissues that are not in homeostasis, and so on.
Although plant and animal cells have some structural differences, to maintain homeostasis, they undergo the same processes of getting energy from food, getting rid of waste, and reproducing.
Both plants and animals stay alive because of the ability of their cells to create stable internal environments. In fact, even single-celled organisms need homeostasis to survive.
2. How does the organization of an organism relate to zation homeostasis? (Hint:rela Think about a car.)
Cell Processes and Homeostasis
So, how does the “work” of homeostasis get done in cells? Cells have structures that function to maintain homeostasis. We’ll discuss some of those processes and structures in the following paragraphs. All cells need certain substances to function and maintain homeostasis. Food, water, and nutrients must be able to go into the cells, and waste must be able to leave. The key structure for this is the cell membrane. All cells have a cell membrane, which serves the same purpose as the door of a house. The cell membrane acts as the cell’s gatekeeper. Unlike a front door, however, the cell membrane surrounds the entire cell, allowing only water and certain molecules to diffuse in and out as needed. The process of diffusion moves molecules from an area where there are many of them to an area where there are very and osmosis to move needed substances inside and to remove unwanted substances (waste). The goal is to balance molecules and water on either side of the cell membrane. The processes of diffusion and osmosis are key to maintaining homeostasis.
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move, grow, and reproduce. Glucose is the most important energy source for all organisms. This means that glucose is the molecule that cells use the most to get energy. During photosynthesis in plants (and a few other organisms), glucose is made from carbon dioxide, water, and sunlight. Photosynthesis occurs in the chloroplasts of plant cells. Humans and animals don’t have chloroplasts, so they don’t perform photosynthesis. But their cells do perform an equally important process called cellular respiration. Glucose is broken down during cellular respiration, and energy is generated from it. This process occurs in a cell structure called the mitochondrion (plural: mitochondria). All plant and animal cells perform cellular respiration to generate the energy that is needed to function. Cells that use a lot of energy, such as muscle cells, have more mitochondria than cells that do not use as much energy. Each cell can have hundreds of thousands of mitochondria if needed.
Healthy cells will continue to grow, but eventually, this growth makes it hard for the cell to maintain homeostasis. Larger cells have trouble moving bigger amounts of nutrients and waste through the cell membrane. When the cell can no longer keep an internal balance, it divides to create two daughter cells. This process allows a cell to reproduce itself. Inside the cell is a structure called the nucleus, which contains genetic material. The nucleus gives a cell the ability to pass on genetic information to the next cell “generation.”
3. Plants make the glucose that they use in cellular respiration to get energy. Humans and animals don’t makeHuma H glucose but do perform cellular respiration. ucose but do pe se dop Where do humansrespirat and animals get their glucose from? animals get nimals
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Homeostasis can be disrupted at all levels of biological organization and in many different ways. Any disruption in homeostasis can lead to sickness, disease, or even death. Imbalances in homeostasis +) and chloride (Cl-), and lack of good nutrition. They can also be caused by disruptions in energy production and heredity (genetics). Even environmental factors, such as toxins, can disrupt the delicate balance that is required for homeostasis.
One common example of homeostatic disruption leading to disease is diabetes. People who have type 1 diabetes cannot make the amount of insulin that is needed to transport glucose into their cells, or they may even be unable to produce insulin at all. Those with type 2 diabetes can produce insulin, but the cells fail to uptake glucose. As a result of cells not taking in glucose, the concentration of glucose in the blood can increase drastically for both types of diabetes. Without glucose, cells can’t generate energy. Without energy, cellular processes do not occur, and homeostasis is compromised. People with diabetes can regulate their insulin by consistently testing their blood to monitor their glucose levels. Insulin injections allow these patients to help their cells lower blood glucose levels and maintain homeostasis. Sometimes, blood glucose levels can be controlled by a healthy, balanced diet.
Dr. Chandrabali Bhattacharya, PhD Department of Chemistry and Biochemistry University of Nevada, Las Vegas
Chandrabali Bhattacharya is researching the development of glucose-responsive material for smart insulin. Smart-insulin systems would be able to quickly respond to elevated blood glucose levels and deliver the correct amount of insulin that is needed. The system would be able to stop delivery once a normal blood glucose level is established.
Currently, patients have the option of an implanted glucose monitor that alerts them when levels are off. There is also a device that delivers insulin through a port in the body, but the person must input the amount of insulin that is needed. A smart device that can do both for a patient with uncontrolled diabetes could be lifesaving.
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Organisms have biological levels of organization. Cells work together to make tissues. Tissues work together to make organs. Organs work together to function as organ systems, and organ systems work together to make a functioning organism. Homeostasis is the state of having internal balance. Each level of organization strives to maintain homeostasis so that the organism can be at optimum health. In other words, cells that are not in homeostasis lead to tissues that are not in homeostasis, and so on.
A cell has many structures that work to maintain homeostasis. The cell membrane allows substances into and out of the cell as needed. Chloroplasts in plants convert carbon dioxide, water, and sunlight into glucose. Glucose is used during cellular respiration to generate energy for cells to function. Cells need energy for lots of functions, which include moving large molecules through the membrane, generating energy, reproducing, and removing waste products along with many other jobs.
The process of cellular respiration to get energy occurs in cell structures called mitochondria. A cell can have just a few mitochondria or hundreds of thousands of mitochondria depending on how much energy it needs. When a cell reproduces, it uses the genetic information in the nucleus.
Optimum health can be obtained only when homeostasis is maintained. If one area is out of balance, the whole organism suffers. Diabetes is an example of disrupted homeostasis. In diabetes, the cells can’t take in glucose, and blood glucose levels become high, causing serious health problems.
Connect It
We have discussed how human and animal cells are organized into levels in which homeostasis must be maintained. Recall that a group of cells works together to make tissue. A group of tissues working together makes an organ. A group of organs functioning together makes an organ system. Finally, all organ systems function together to make a whole organism that must maintain homeostasis to continue in optimum health.
Are plants organized in the same way? As funny as it may sound, plants are organized into similar levels. Plants have cells that work together to form tissue. An example is plant vascular tissue that transports water and nutrients throughout the plant. Plant tissues work together to make organs. Plant organs are their leaves, stems, and roots. In plants, organs work together to make organ systems—the root and shoot systems. All of these levels must be kept in tip-top shape for a plant to maintain homeostasis.
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1 What is the relationship between photosynthesis and cellular respiration that assists homeostasis?
A Glucose is made during cellular respiration and is used for energy during photosynthesis.
B Homeostasis is maintained mostly by photosynthesis and only slightly by cellular respiration.
C Both photosynthesis and cellular respiration make glucose.
D Glucose is made during photosynthesis and broken down for energy during cellular respiration.
2 Which cell structure plays a part in removing waste from cells?
A Chloroplasts
B Cell membrane
C Ribosomes
D Plant roots
3 How does cellular respiration work to maintain homeostasis in organisms?
A Cells reproduce during cellular respiration, which is important in homeostasis.
B Glucose is created during cellular respiration and is used for important cell functions.
C Glucose and oxygen are converted to energy that is used for important cellular functions.
D Glucose, the important energy molecule, is made during cellular respiration.
4 The cell membrane can be thought of as the front door of a cell EXCEPT that–
A it surrounds the cell
B it lets nothing in or out.
C it surrounds only parts of a cell.
D it doesn’t have a lock.
5 How are mitochondria like batteries?
A
B Both have the same shape.
C Both produce light.
D Both produce energy.
6 How can information about homeostasis be used in real life? Write a paragraph with three to
Cell Organelles
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Onion cells look quite beautiful under a microscope. These cells are three-dimensional and have a clear, circular nucleus in each one. But how are they similar to the cells in humans? Is the nucleus the only organelle that both plants and animals have?
1. How do the organelles in onion plants ganellescompare g with those within human cells?
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To answer this question, think about the purposes that cells serve and organelles that would be needed for those purposes. What functions would cells carry out? Are there any cell organelles that plants need but not animals or vice versa?
All living things contain basic building blocks called cells. They are generally too small to be seen with the naked eye and require a microscope. Although all plants and animals have cells, they are not identical to each other.
Plant cells are found in organisms that conduct photosynthesis, including carnivorous and underwater plants. Plant cells are usually rectangular and contain organelles that animal cells do not have, such as
(Our focus will remain on the two basic cell types for now.)
Generally, plant cells are larger than animal cells. Animal cells are surrounded by a single plasma membrane that contains a nucleus and organelles that are themselves membrane bound. They are more round in shape than plant cells because they do not have an outer structure that limits them to a rectangular shape. Aside from the spherical shape shown in the image, animal cells can be rod shaped,
Plant Cell
Animal Cell
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cord while the more rounded epithelial cells (right) line many of the organs in the human body. They can be found on the skin and in various organs.
Interestingly, the largest animal cell on Earth is the ostrich egg, measuring 12.7 cm, or about 5 in.
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2. Are consideredorganelles living 2. Are organe e org ideredthings? dered
Small structures called organelles can be found inside every plant and animal cell. The word organelle literally means “little organ” and describes various structures inside plant and animal cells that perform a variety of functions. The organelles in both plants and animals are similar and perform similar functions. They work together to form tissues, which then form organs. Let’s take a closer look at these structures. TissueOrgan
3. How are tissues,organelles, and w are org organs related?
Vacuole
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The nucleus is similar to the brain in an animal. It directs cellular activity and is one of the largest organelles. You may remember this organelle as the one that differentiates eukaryotic cells from prokaryotic cells. The nucleus contains and stores the deoxyribonucleic acid (DNA) that is found in all living cells and determines the traits that are expressed by organisms. In prokaryotic cells, the
There is only one exception to the rule that all plant and animal cells have a nucleus. Mature red blood cells in animals lack a nucleus because they eject all of their organelles, making the cells themselves concave in shape. This enables them to carry more hemoglobin and, in turn, more oxygen to the body.
The cell membrane differentiates the inside from the outside of the cell by surrounding the material inside the cell. You may have heard this referred to as a phospholipid bilayer, meaning a double layer of oil molecules. Every living cell has a cell membrane regardless of whether it is a plant cell or an animal cell. The cell membrane protects the cell and helps the cell receive outside stimuli. It also helps regulate the movement of nutrients, water, and oxygen into and out of the cell by letting in substances that the cell needs and keeping out anything else.
Inside the cell membrane, a thick solution called cytoplasm cushions the other organelles and serves as a site for chemical reactions. This watery solution holds all of the organelles inside the cell.
An artist’s rendering of cells shows the nucleus, cell membrane, and cytoplasm in animal cells.
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one vacuole Plant cells usually have one large vacuole. Its main function is to help maintain the balance of water and waste in a cell. You may have seen a droopy plant on a hot summer day. A droopy plant has lost water from its vacuoles, which are similar to empty plastic bags, and is unable to stand up straight. When you water the vacuole in each cell.
Animal cells have multiple smaller vacuoles. These vacuoles store water, nutrients, and waste.
4. What is the effect of a plant’s vacuolesuolesdehydrated?becoming bec
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mitochondrion generates most of the energy that is needed for the cell and makes it available for use. It is often referred to as the powerhouse of the cell. This organelle converts glucose and oxygen to the energy that the cell uses to function. Animal liver and muscle cells contain many more mitochondria than other organ types. The word mitochondrion is irregular, and the plural form of this organelle is mitochondria.
Ribosomes in plant and animal cells are spread throughout the cytoplasm. They also surround the nucleus on another organelle called the endoplasmic reticulum (ER). These spherical organelles
A close-up rendering of a cell’s mitochondrion
Ribosomes
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Plant cells have two organelles that are not found in animal cells: a cell wall and chloroplasts.
The cell wall is made mainly of cellulose and creates a rigid outer structure. This gives the plant cell its characteristic rectangular shape, but it also limits the diversity of cell types that a plant can create. It also limits abilities like movement because it gives plant cells a stiff structure. This rigidity allows plants, even those with very thin stems, to stand up straight and support the weight of branches and leaves.
Plant cells also have chloroplasts. These organelles contain the pigment chlorophyll, which absorbs energy from sunlight. Chloroplasts are like solar panels, absorbing and storing the Sun’s energy for photosynthesis. Plants need to undergo photosynthesis to create their own food. When the chlorophyll breaks down in autumn due to reduced sunlight intensity and cooler temperatures, it reveals other leaf pigments, such as red, orange, and brown.
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Plant Cell
Cell wall
Chloroplast
Cell membrane
Nucleus
Ribosomes
Cytoplasm
Mitochondria
Vacuole
5. Why do plant cells need 5. Why y chloroplasts while animal cells do not?wh
Animal Cell
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infection in humans.
The vaccine that their team developed does not contain any live virus. Rather, it uses genetic material to trick the body’s cells into producing bits of a protein that mimics pieces of the coronavirus. These bits of
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Plant and animal cells have organelles, literally “little organs,” that perform a variety of functions for the organisms. Both types of cells have some of the same organelles, including the nucleus, the cell membrane, the cytoplasm, vacuoles, ribosomes, and mitochondria. Plant cells have two additional organelles, a cell wall and chloroplasts. Organelles perform a variety of functions, including substance
Connect It
How would you describe the similarities and differences between onion and human cell organelles?
Onion cells are plant cells, which have some of the same organelles as animal cells. For example, both have a nucleus, which makes them eukaryotic. The cell membrane provides a boundary between the inside and outside of both types of cells, and the cytoplasm gives structure and cushion to both types of cells. Both types of cells have ribosomes and at least one vacuole.
Like all plant cells, onion cells have a cell wall and chloroplasts. This sets them apart from animal cells. In addition, onion cells have one large vacuole, and human cells have several smaller ones.
The data table below compares the main organelles and lists whether they are present in plant cells, animal cells, or both.
Organelle
Plant Cell Animal Cell
Chloroplasts
Advanced Topics
Not all cells are the same. Some cells are prokaryotic while others are eukaryotic. In addition to this distinction, the structures of cells can be different. The structure of a cell organelle is related to its function. For example, a brain cell does not have the same structure or shape as a bone cell. This is because the two cells perform unique functions. However, in both cells, the cell membrane acts as a highly selective barrier. This barrier allows only certain materials into or out of the cell in processes called passive transport and active transport.
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Summarize It
1 Which of the following cellular functions does NOT happen in the nucleus?
A Storage of DNA
B Storage of materials that are used to make food
C Control of the activities of the cell
D Direction of the growth and development of the cell
2 One main difference between plant and animal cells is that–
A only plant cells need to generate energy for the organism to use.
B plant cells have fewer organelles than animal cells do.
C animal cells are larger than plant cells.
D plant cells have chloroplasts and cell walls while animal cells do not.
3
A cell membrane.
B ribosome.
C mitochondrion.
D cell wall.
4
A keep outside pollutants from contaminating the cell’s cytoplasm.
B
C create energy from sunlight.
D direct the growth and development of the cell.
5 How does a mitochondrion in an animal cell compare to a ribosome?
A The ribosome is the powerhouse of the cell while the mitochondrion makes proteins.
B makes proteins.
C The mitochondrion is like a battery generating energy while the ribosome makes proteins that are needed by the cell.
D The mitochondrion keeps the cell’s cytoplasm intact while the ribosome controls the cell’s energy and growth.
6 Organelle Name Function
Cell membrane
Cell wall
Nucleus
Ribosomes
Cytoplasm
Mitochondria
Chloroplasts
Organism Organization
1. How do you think breathing . y relates to cellular hinkrespiration?
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2. What are three things you can thinkthg hg of that are in thi y a hierarchical arrangement?
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cell
Micrographia
Micrographia
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Animal Tissue
Muscle tissue
Connective tissue
Nervous tissue
Epithelial tissue
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Plant Tissue Types
3. How do cells relate to tissues in plants? Give an example to support your supportexplanation. y p
Organs
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Small intestineColon
Liver
Heart Lung
Esophagus
Mouth
Stomach
Spleen
Kidney
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Organ Systems
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4. Explain the relationship of t organs to nssystems.organ tg
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Donita Brady, PhD University of Pennsylvania
Cancer cells dividing
Normal cells
Tumor forming
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How does breathing relate to cellular respiration?
Human Body Systems
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Have you ever had a sunburn? It hurts! Sunburns happen when your skin, which is your body’s biggest organ, suffers damage from the Sun’s ultraviolet rays. After a few days, your skin heals, goes back to its normal color, and does not hurt anymore. What is involved in healing from injuries and burns in particular? How does your body know what to do, and what systems help you heal?
1. What body systems are involved . What in healing from stems are in are ahealingsunburn? ng
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Every organ in the human body serves a particular function. A function is what something does. Each organ is part of at least one body system. A system is a group of interacting, interrelated, or interdependent elements that form a complex whole. A system has a given function, such as helping your body digest food, exchange gases, or resist infection.
The human organism is made of several distinct body systems. Those systems consist of organs, which consist of tissues. Tissues are made of cells. The cell is the smallest, most basic structural unit in your body.
The human body is made of several systems that work together to help you perform important life processes.
2. Imagine you were asked to model onew magine y of the systems in the picture above. What would you needabo to know about the t wo system to determine how to make your model?
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Our circulatory and respiratory systems are involved in the exchange of gases like oxygen and carbon dioxide into and out of body tissues.
The circulatory system is a group of organs that work together to circulate blood through the body, supply oxygen and nutrients, and remove waste. Its functions include blood circulation, the delivery of oxygen and nutrients to cells, the transportation of cellular waste (carbon dioxide) out of the body, and more. This system also helps with temperature regulation. The main organs of the circulatory system consist of the heart, arteries and veins, capillaries, and blood. An adult organism has between 1.2 and 1.5 gal. of blood.
The respiratory system is composed of the trachea, lungs, mouth, and nose. The trachea is also known as the windpipe. The function of the respiratory system is to exchange oxygen and carbon dioxide in the lungs.
The lungs are the main organs of the respiratory system. The heart, which is part of the circulatory system, is located in the center of the chest, under the breastbone and between the lungs.
3. How do the circulatory and respiratory systems work together to support life getherprocesses? supp
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The human skeletal system provides structural support to the body and protects the major internal provide form, support, and stability as you perform life functions. The brain is protected inside the skull, and the rib cage protects the lungs, heart, liver, and stomach. Long bones create red and white blood cells and platelets, which help our blood clot when we sustain injuries. The skeletal system also stores calcium and other minerals.
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muscular system is a group of organs that function to provide mechanical movement and warmth for the body. It is composed of skeletal muscle, smooth muscle, cardiac muscle, and tendons. Cardiac muscle is the muscle in the heart, which beats to circulate blood around the body. Skeletal muscles are attached to bone and make the bone move as they contract or relax.
The muscular and skeletal systems work together and are often called the musculoskeletal system.
4. Sometimes, the skeletal and muscular systems are grouped together into one ystems are grp stems ag system called theo ether in ystemmusculoskeletal called system. Do you think the systems should be grouped syste k together or keptgroup separately? Why? kep er or kep
The human muscular system from different angles
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The human digestive system takes the foods that you eat and breaks them down, providing energy for the body. The digestive system is a group of organs that work together to break down food by physical and chemical processes into nutrients that the body can use. This system is composed of the mouth, esophagus, stomach, small intestine, large intestine, gallbladder, liver, pancreas, rectum, and anus. This system processes food, delivers nutrients to the bloodstream, and removes solid waste from the body.
The organs in the human digestive system
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The human urinary system
The urinary system form of urine. This is sometimes called the excretory system because its main function is to remove excess waste material from the body. Kidneys, ureters, the bladder, and the urethra are the organs in this system.
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The organs in human reproductive systems
The reproductive system is a group of organs that function to produce offspring. It is composed of the testes, fallopian tubes, ovaries, and uterus. The function of the male reproductive system is to fertilize the egg, which is produced, fertilized, and held in the female reproductive system until birth.
5. The human digestive system is one of the most gestive system e syst complicated in the human body. What t is one area of studyWh W that interests you and involves the hat y in digestive system?
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The integumentary system is a group of organs and tissues that protect the body from external damage, UV radiation, and water loss. It also helps regulate body temperature, aids in the excretion of waste (sweat), creates vitamin D, and receives information from the external environment. It consists of the hair, skin, and nails.
Nervous, Immune, and Endocrine Systems
The nervous system communicates between different body systems and activates body responses to stimuli. It is responsible for all cognitive processing, including the development of language, thought, attention, memory, and imagination. The brain, spinal cord, and nerves make up this important system.
The organs in the nervous system
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immune system consists of white blood cells, antibodies, the lymphatic system, spleen, thymus, and bone marrow. Finally, the endocrine system regulates the body by secreting hormones into the bloodstream and controlling important body processes. It controls growth, reproduction, and metabolism. This system includes the thyroid gland, pituitary gland, and adrenal gland.
Homeostasis
for survival.
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Dr. Lisa Rae, MD Temple Burn Center
Lisa Rae is the director of the Temple Burn Center and an associate professor of surgery at the Katz School of Medicine. She serves on the American Burn Association’s National Faculty for the Advanced Burn Life Support Committee. She specializes in burn injuries, surgical critical care, and emergency general surgery.
The Temple Burn Center treats hundreds of patients each year who have sustained major burns and need inpatient care in a hospital. It uses a burn treatment called the RECELL system, in which a small
only about 30 minutes and reduces infection because it reduces the amount of time that a patient’s burn wounds are open to the air.
Skin burns often need treatment in a hospital or clinic. Healing can be slow and involves a number of body systems.
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The human organism consists of several organ systems with different functions. The circulatory system routes blood throughout the body. The respiratory system exchanges oxygen and carbon dioxide. The skeletal system helps support and stabilize the body. The muscular system provides movement. reproductive system creates offspring. The integumentary system protects internal organs from damage. The nervous system communicates messages between body systems. The immune system defends against infection. The endocrine system regulates body processes.
Connect It
What body systems are involved in healing from a sunburn?
Skin is an organ that is part of the integumentary system. Sunburn damages the outer layer of this organ. The nervous system sends signals to the brain telling it that a part of the body has been damaged. The immune system is involved because this system helps the body defend against infection, so it is activated when the skin is burned. Extra blood with red and white cells made in the skeletal system is sent to the area to help the body heal from the damage. The blood arrives at the burned area; it is moved around the body by the circulatory system.
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Summarize It
1 Which body system activates body responses when it is faced with stimuli from the outside environment?
A Nervous system
B Circulatory system
C Endocrine system
D Immune system
2 Which two body systems work together to facilitate movement?
A Reproductive and integumentary systems
B Immune and digestive systems
C Circulatory and muscular systems
D Muscular and skeletal systems
3 Which of the following systems is NOT involved in the processing of information or substances from the outside environment?
A Nervous system
B Integumentary system
C Reproductive system
D Respiratory system
4 Which body system creates platelets, which help the blood clot and stop bleeding after an injury?
A Integumentary system
B Immune system
C Skeletal system
D Nervous system
5 Fill in the table by identifying the body system according to its organs and function.
6 Describe the organs and systems that are responsible for exchanging oxygen and carbon dioxide.
Infectious Diseases
infectious disease
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strep throat are results of infectious a hr agents. What are some otherW infectious agents that you can fectious ag think of? hat you
2. What are some diseases that you have caught that were contagious? th ght How did they make were contagiou e contag you feel?hey
viruses
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3. How are bacteria and viruses different from each other?
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fungi
photosynthesis.
4. Some fungi look like plants because 4. Some they grow out of ke beca the ground. How they grow out hey gro are fungi different H groun from fungiplants? diff
Parasites
make the host organism weaker. seriously harm humans.
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5. Parasites, such as ticks, nourishmentgetfrom g the blood of other organisms. What other organisms.organisms W rganism get othernourishment organ her organ from blood? t nourish
Combating Infectious Agents with Medicine
Dr. Marion Koopmans, DVM, PhD Erasmus
Medical Center
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Taxonomy
1. How could we organize the organisms in a organize niz pond based on nism their similarities and differences from one another?
Taxonomy
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prokaryotic cells
Eukaryotic cells
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The Three Domains Domains
Kingdoms
The Six Kingdoms
The Six Kingdoms
autotrophs
heterotrophs
2. Describe the three ways that organisms are rganisms ganism different kingdoms. Use new vocabulary kingdo g in your explanation. Use an organism that makes its own food an organism that
Characteristics of the Domains and Kingdoms
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kingdom Archaea
Domain Bacteria and kingdom Bacteria cyanobacteria
E. coli or i Lactobacillus acidophilus.
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3. How are members of kingdom Archaea and ngdomBacteria Arc om A different?
• Kingdom Protista
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• kingdom Plantae
kingdom Fungi
Kingdom Animalia
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4. How would energy supplies in ecosystems be energy supp supp affected if there in ecosystems n ecosy were no fungi or ereanimals?fg
Ocampo-Friedmann Microbiologist and Botanist
Roseli
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GLOSSARY OF TERMS
air mass cell
air mass: a body of air extending over a large area (1,000 miles or more) that develops and retains specific characteristics of pressure, temperature, and humidity
air pressure: the force exerted by the atmosphere on Earth’s surface by the weight of the air above the surface
atmospheric movement: global air circulation patterns within the atmosphere held to Earth by gravity and warmed as heat radiates from Earth; influenced by convection of warm, less dense air (rises and spreads out) and cold, dense air (sinks)
autotroph: an organism that makes its own food
animal cell: eukar yotic cell surrounded by a plasma membrane that contains a nucleus and organelles that are membrane bound
applied force: the push or pull that is exerted on an object by another object
at rest: the state of an object when it is not in motion
atmosphere: the layer of gas surrounding a planet that is held in place by gravity
bacteria: one of the three taxonomic domains; a highly diverse group of singlecelled, prokaryotic organisms
balanced forces: forces on an object that do not change the motion of the object
biosphere: the sum of all living matter on Earth
cell: the basic structural and functional unit of living organisms
GLOSSARY OF TERMS
cell membrane constant speed
cell membrane: a lipid barrier that encloses the cytoplasm and controls what enters and exits the cell
cell theory: a theor y that states the following: all life is made up of cells, cells are the fundamental unit of life, and all cells come from preexisting cells
cell wall: a tough, protective barrier that surrounds the outer membrane of some types of cells
chemical potential energy: the energ y stored in chemical bonds of a substance
circulatory system: the group of organs that work together to circulate blood through the body, supply oxygen and nutrients, and remove waste
climate: average weather patterns for a particular region
coastline: the outline or shape of a coast or the boundar y between land and a lake or ocean cold front: the border between an advancing cold air mass and a retreating warm air mass
chemical weathering: the chemical processes that break down rocks using chemicals found in the atmosphere
chloroplast: a membrane-bound organelle in plants that is the site of photosynthesis
conduction: transfer of thermal energ y that occurs in solids, liquids, and gases when two substances of different temperatures touch constant speed: the rate of fixed speed per time
GLOSSARY OF TERMS
convection domain Archaea
convection: heat transfer caused by the rising of hotter, less dense fluids and the falling of cooler, denser fluids
cryosphere: the places on Earth where the water is frozen all the time
cytoplasm: the jellylike material inside the outer membrane of a cell that holds the nucleus, organelles, and other components of the cell
digestive system: the group of organs that work together to break down food by physical and chemical processes into nutrients that the body can use
direction: a straight path that an object can move along
distance: a measure of how far apart two objects are
delta: a triangular landform formed by deposition of sediments at the mouth of a river as it empties into another body of water deposition: the process by which gravity, water, wind, and ice deposit weathered and relocated sediment
distance-time graph: a graph illustrating changes in motion that shows time on the x-axis and distance on the y-axis
domain Archaea: one of the three taxonomic domains of organisms; consists of a specialized group of unicellular prokar yotes that can live in extreme environments
GLOSSARY OF TERMS
domain Bacteria function
domain Bacteria: one of the three taxonomic domains of organisms; includes prokaryotic, single-celled organisms that lack a membrane-enclosed nucleus and can be classified by shape
domain Eukarya: one of the three taxonomic domains of organisms; has cells that contain a membrane-enclosed nucleus
energy transfer: movement of energ y from one system to another equilibrium: a condition in which all competing influences are balanced
erosion: the process by which gravity, water, wind, and ice remove and transport sediment from one place to another
elastic potential energy: potential energ y stored as a result of deformation of an elastic object, such as the stretching of a spring
endocrine system: the group of organs that regulate the body by secreting hormones into the bloodstream; also control growth, reproduction, and metabolism
eukaryotic cell: a cell with a nucleus and membrane-bound organelles
flood: a rising body of water that submerges normally dr y land
force: a push or pull that can change the motion of an object
friction: a force that resists the motion of two surfaces sliding across one another
energy: the ability of a system to do work; required for changes to happen within a system
function: what something does
GLOSSARY OF TERMS
fungi: heterotrophic eukar yotes that reproduce through asexual spores, break down dead materials, and can spread disease
geosphere: portion of Earth that includes Earth’s interior, rocks and minerals, landforms, and processes that shape Earth’s surface glacier: a large, slow-moving, long-lasting accumulation of snow and ice that develops on land gravitational potential energy: the energ y stored in an object due to its position gravity: the force that causes objects with mass to attract one another hazardous weather: severe or dangerous weather phenomena that threaten life and property
heterotroph: an organism that must consume other organisms for energ y high-pressure air mass: an air mass with greater atmospheric pressure than the surrounding air masses; air moves away from the center of the high pressure, traveling in a clockwise direction in the northern hemisphere and a counterclockwise direction in the southern hemisphere
homeostasis: the tendency of an organism or cell to maintain a balanced state to maintain health and function
horizontal: describes the direction of motion from side to side, perpendicular to a corresponding vertical line; from side to side; parallel to the horizon
hurricane: a large tropical weather system consisting of an extremely low-pressure air mass with heavy rains and wind speeds of at least 119 km/h
GLOSSARY OF TERMS
hydrosphere landform
hydrosphere: all the water on Earth’s surface; includes all water sources above and below the surface
immune system: the group of organs that defend the body against infectious diseases
infectious disease: illness caused by bacteria, viruses, parasites, or fungi that can be passed directly or indirectly to another person
integumentary system: a system of organs and tissues that protects the body from external damage and water loss
kinetic energy: energ y of motion
kingdom Animalia: kingdom of heterotrophic eukar yotes that includes all animals
kingdom Archaea: kingdom of prokaryotic, single-celled organisms that live in extreme environments
kingdom Bacteria: kingdom of prokaryotic, single-celled organisms that lack a membrane-enclosed nucleus and can be classified by shape
kingdom Fungi: kingdom of heterotrophic eukaryotes that reproduce through asexual spores and have cell walls
kingdom Plantae: kingdom of autotrophic eukar yotes that includes all plants
kingdom Protista: kingdom of single-celled and simple multiple-celled eukar yotic organisms
lake: a large body of water surrounded by land landform: feature on the surface of Earth, such as mountains, hills, dunes, oceans, or rivers.
GLOSSARY OF TERMS
normal force: the force generated by a surface in opposition to an object pressed upon it low-pressure air mass
low-pressure air mass: an air mass with less atmospheric pressure than the surrounding air masses; air moves toward the area of low pressure, traveling in a counterclockwise direction in the northern hemisphere and a clockwise direction in the southern hemisphere
magnetism: a force that attracts or repels objects toward or away from each other; caused by electrons in a substance
mitochondrion: the organelle that functions in energ y production; the power factor y of the cell
motion: the change in an object’s position with respect to time and in comparison with the position of other objects used as reference points
mountain: a large landform that is formed by volcanoes or the movement of the tectonic plates
multicellular: a category of organisms made up of more than one cell and of different types of cells
muscular system: a group of organs that provide mechanical movement and generate warmth for the body
natural disasters: any event or force of nature that causes great damage or loss of life, such as tornadoes, hurricanes, and floods
nervous system: a group of organs and tissues specialized for the rapid transmission and processing of information
net force: the sum of all the forces acting on an object
GLOSSARY OF TERMS
nucleus ribosomes
nucleus: a membrane-bound organelle in eukar yotic cells that contains the DNA; the control center of the cell
organelle: a structure inside a cell that performs a specialized function organism: a self-contained living thing
parasite: an organism that lives in or on another organism (host) and derives nourishment from it, resulting in harm to the host organism
photosynthesis: a chemical reaction during which plants convert radiant energ y from the Sun to chemical energ y; the reaction converts carbon dioxide and water into sugar (glucose) and oxygen
physical weathering: geological process of rocks breaking apart without changing their chemical composition
plant cells: cells found in plants that are generally rectangular in shape and contain certain organelles that animal cells do not have, such as chloroplasts and cell walls
potential energy: energ y that is stored in a system or object
prokaryotic cell: a cell lacking a nucleus or any other membrane-enclosed organelle
radiation: the transfer of energ y by the movement of electromagnetic waves or subatomic particles
reproductive system: a group of organs that function to produce offspring
respiratory system: the group of organs that supply oxygen to the blood and get rid of carbon dioxide
ribosomes: small, spherical organelles that are responsible for making proteins in cells
GLOSSARY OF TERMS
river: a natural flow of water that follows a path into another body of water
sand dune: hill formed by the wind blowing sand
sediment: Earth material that is broken down by processes of weathering; can be eroded and deposited by the agents of water, wind, ice, and gravity
skeletal system: a group of organs that function to provide structural support and protect internal organs
speed: the rate of change of position (or distance traveled) with respect to time
structure: the arrangement of parts that form a living thing
Sun exposure: exposing the body’s skin to the Sun
system: a group of interacting, interrelated, or interdependent elements forming a complex whole
taxonomy: the branch of science that formally names and classifies organisms by their structure, function, and relationships
thermal energy: the total kinetic (motion) energ y of the tiny particles that make up matter; the faster the particles move, the warmer the matter becomes
thunderstorm: a storm that is formed by the quick movement of warm, moist fronts into the cool atmosphere; also known as a lightning storm
tornado: a violently rotating column of air extending from a thunderstorm to the ground with wind speeds between 40 and 318 miles per hour (mph)
river tornado
GLOSSARY OF TERMS
unbalanced forces y-axis
unbalanced forces: forces on an object that cause change in the motion of the object
unicellular: a category of organisms made up of one cell
urinary system: the group of organs that filter the blood and remove waste urine
weather: the day-to-day state of the atmosphere
weathering: the mechanical or chemical processes by which gravity, water, wind, and ice break rock into smaller pieces
wind: a natural movement of air, sometimes with considerable force, from an area of high density and pressure to an area of low density and pressure
vacuole: the organelle that stores water and food in both plant and animal cells
vertical: describes the direction of motion up and down, perpendicular to a corresponding horizontal line; from top to bottom; perpendicular to the horizon
virus: a nonliving particle dependent on host cells for replication of genetic material
warm front: the boundar y between an advancing warm air mass and a receding cooler air mass
x-axis: the horizontal line with labels on a coordinate grid; often used for representing time
y-axis: the vertical line with labels on a coordinate grid; often used for representing distance
