IGCSE BIOLOGY EXAM PREP

1 Characteristics and classifications of living organisms

1 Characteristics and classification of living organisms

Getting exam ready Understanding the question

TI AL

Command words

To help you prepare for your exams, this book guides you through a framework of exam skills that will help you to show what you know about Biology in the Cambridge exam context; from the various elements of understanding the question, to writing a good response, to developing the kind of behaviours and habits that will support you along the way.

In this chapter you will check that you know the key concepts of the characteristics and classification of living organisms and practice how you show this knowledge in an exam.

Alongside recalling your knowledge on characteristics and classification of living organisms, in this chapter you will also practice understanding command words.

The relevant part of the Cambridge Exam Skills Framework is as follows:

EN

Answering questions and testing your knowledge is very important for your memory. Every time you recall information and write an answer, your knowledge and understanding gets stronger. Once you have consolidated your memory, you can better concentrate on what in particular the exam question is asking you to do.

Extract from the Cambridge Exam Skills Framework

Knowledge recall questions: Questions that increase your memory of what you know about the characteristics and classification of living organisms

2

Exam skills questions: Questions that practice showing what you know about the characteristics and classification of living organisms in an exam

N

For that reason, there are three kinds of question in this chapter.

1

O

Self Assessment questions: Questions that help you monitor your own progress

3

&

recall and describe the seven characteristics of living things

•

use the binomial system to name organisms

•

use and construct keys

•

classify vertebrates and arthropods

D

R

AF

•

T

In this chapter, you will:

2

C

You will also find recall questions through this chapter on something you have already covered. This is because your memory is best increased by a technique called interleaving. This is when you return to a previously studied topic within a certain timeframe to make sure that you remember it properly.

LEARNING OBJECTIVES

Exam skill

Understanding the exam question

Sub-skill

Interpreting command words

Objectives

• •

FI D

Exam questions are very specific and are looking for certain things, so you need to be ready for the approach that they take so that you can really show what you know.

•

Identify specific command words in the exam question.

Understand the meaning of specific command words and what they are instructing you to do.

Distinguish between different command words.

In this chapter you are going to increase your understanding of what exam questions are asking you to do. An important part of understanding exam questions is to know what command words are and what they mean.

EXAM SKILLS OBJECTIVES In this chapter, you will: •

show that you understand the ‘describe’ command word and answer a ‘describe’ question.

•

think about your learning and identify any areas where you might need some more support

•

plan how to address these areas, try it out, and reflect on how successful it was

The following exercise explores the command word, describe, which means to state the points of a topic or give characteristics and main features.

DEFINE THESE TERMS Write your own definition for the following key terms: •

describe

3

1 Characteristics and classifications of living organisms

1 Characteristics and classification of living organisms

Getting exam ready Understanding the question

TI AL

Command words

To help you prepare for your exams, this book guides you through a framework of exam skills that will help you to show what you know about Biology in the Cambridge exam context; from the various elements of understanding the question, to writing a good response, to developing the kind of behaviours and habits that will support you along the way.

In this chapter you will check that you know the key concepts of the characteristics and classification of living organisms and practice how you show this knowledge in an exam.

Alongside recalling your knowledge on characteristics and classification of living organisms, in this chapter you will also practice understanding command words.

The relevant part of the Cambridge Exam Skills Framework is as follows:

EN

Answering questions and testing your knowledge is very important for your memory. Every time you recall information and write an answer, your knowledge and understanding gets stronger. Once you have consolidated your memory, you can better concentrate on what in particular the exam question is asking you to do.

Extract from the Cambridge Exam Skills Framework

Knowledge recall questions: Questions that increase your memory of what you know about the characteristics and classification of living organisms

2

Exam skills questions: Questions that practice showing what you know about the characteristics and classification of living organisms in an exam

N

For that reason, there are three kinds of question in this chapter.

1

O

Self Assessment questions: Questions that help you monitor your own progress

3

&

recall and describe the seven characteristics of living things

•

use the binomial system to name organisms

•

use and construct keys

•

classify vertebrates and arthropods

D

R

AF

•

T

In this chapter, you will:

2

C

You will also find recall questions through this chapter on something you have already covered. This is because your memory is best increased by a technique called interleaving. This is when you return to a previously studied topic within a certain timeframe to make sure that you remember it properly.

LEARNING OBJECTIVES

Exam skill

Understanding the exam question

Sub-skill

Interpreting command words

Objectives

• •

FI D

Exam questions are very specific and are looking for certain things, so you need to be ready for the approach that they take so that you can really show what you know.

•

Identify specific command words in the exam question.

Understand the meaning of specific command words and what they are instructing you to do.

Distinguish between different command words.

In this chapter you are going to increase your understanding of what exam questions are asking you to do. An important part of understanding exam questions is to know what command words are and what they mean.

EXAM SKILLS OBJECTIVES In this chapter, you will: •

show that you understand the ‘describe’ command word and answer a ‘describe’ question.

•

think about your learning and identify any areas where you might need some more support

•

plan how to address these areas, try it out, and reflect on how successful it was

The following exercise explores the command word, describe, which means to state the points of a topic or give characteristics and main features.

DEFINE THESE TERMS Write your own definition for the following key terms: •

describe

3

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

1 Characteristics and classifications of living organisms

Write labels for Figure 1.1. Your labels should include short descriptions stating how the plant is showing these characteristics of living things:

Three students answer the question ‘Describe the method used to calculate the average change in the height of three plants.’

•

reproduction

•

growth

Here are the three answers they gave. Which answer do you think addresses the command word in the question? What is wrong with the other answers?

•

sensitivity

•

excretion

Answer 1

The following question asks you to explain something. In an exam context, to explain something means to set out the purposes or reasons for something and support this with relevant evidence. Try it now.

I calculated the average change in height of the three plants in three days to be 1.5 cm. This is more than I predicted.

EN

2 Imagine that someone from another planet is visiting Earth. They see aeroplanes and birds moving through the sky.

Answer 2

Explain to the visitor why birds are alive and aeroplanes are not alive, even though they seem to share some of the characteristics of living things.

FI D

I measured the height of each plant at the start of the experiment. After three days, I measured the height of each plant again. I subtracted the initial height from the final height to find the change in the height of each plant. I then added this value for each plant and divided by three, to find the average value.

REFLECTION What does the command word ‘explain’ mean? How do you know that you’ve demonstrated this?

Answer 3

O

AF

T

&

1.1 Characteristics of organisms

D

R

DEFINE THESE TERMS

Figure 1.1: A plant growing towards the light.

4

QUICK RECALL 1: EXAM SKILLS What is the difference between describe and explain?

C

The average value was 1.5 cm. I think this is because the plants were kept in sunny conditions with lots of water.

Figure 1.1 shows a plant, growing towards the light. Inside its leaves, photosynthesis is taking place. Photosynthesis uses carbon dioxide to make glucose, and releases oxygen.

Look at your answer to question 2. Do you think you would change anything?

If so, try it now using a different coloured pen.

N

I measured the height of each plant at the start of the experiment. After three days, I measured the height of each plant again. I subtracted the initial height from the final height to find the change in the height of each plant. I then added this value for each plant and divided by three, to find the average value.

1

TI AL

1.0 Exam skills

Write your own definition for the following key terms: •

organism

•

respiration

•

sensitivity

1.2 The biological classification system 1

Complete the sentences, using words from the list. binomial healthy

biological living

complete population

fertile

genus

reproduce

group

species

An organism is a (1) ..................... thing. A (2) ..................... is a group of living organisims that can (3) ..................... with each other to produce (4) ..................... offspring.

Each species of organism has a two-word name. This system of naming is called the (5) ..................... system. The first of the two words in the name tells us the (6) ..................... that the species belongs to.

DEFINE THESE TERMS Write your own definition for the following key terms: •

species

•

genus

5

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

1 Characteristics and classifications of living organisms

Write labels for Figure 1.1. Your labels should include short descriptions stating how the plant is showing these characteristics of living things:

Three students answer the question ‘Describe the method used to calculate the average change in the height of three plants.’

•

reproduction

•

growth

Here are the three answers they gave. Which answer do you think addresses the command word in the question? What is wrong with the other answers?

•

sensitivity

•

excretion

Answer 1

The following question asks you to explain something. In an exam context, to explain something means to set out the purposes or reasons for something and support this with relevant evidence. Try it now.

I calculated the average change in height of the three plants in three days to be 1.5 cm. This is more than I predicted.

EN

2 Imagine that someone from another planet is visiting Earth. They see aeroplanes and birds moving through the sky.

Answer 2

Explain to the visitor why birds are alive and aeroplanes are not alive, even though they seem to share some of the characteristics of living things.

FI D

I measured the height of each plant at the start of the experiment. After three days, I measured the height of each plant again. I subtracted the initial height from the final height to find the change in the height of each plant. I then added this value for each plant and divided by three, to find the average value.

REFLECTION What does the command word ‘explain’ mean? How do you know that you’ve demonstrated this?

Answer 3

O

AF

T

&

1.1 Characteristics of organisms

D

R

DEFINE THESE TERMS

Figure 1.1: A plant growing towards the light.

4

QUICK RECALL 1: EXAM SKILLS What is the difference between describe and explain?

C

The average value was 1.5 cm. I think this is because the plants were kept in sunny conditions with lots of water.

Figure 1.1 shows a plant, growing towards the light. Inside its leaves, photosynthesis is taking place. Photosynthesis uses carbon dioxide to make glucose, and releases oxygen.

Look at your answer to question 2. Do you think you would change anything?

If so, try it now using a different coloured pen.

N

I measured the height of each plant at the start of the experiment. After three days, I measured the height of each plant again. I subtracted the initial height from the final height to find the change in the height of each plant. I then added this value for each plant and divided by three, to find the average value.

1

TI AL

1.0 Exam skills

Write your own definition for the following key terms: •

organism

•

respiration

•

sensitivity

1.2 The biological classification system 1

Complete the sentences, using words from the list. binomial healthy

biological living

complete population

fertile

genus

reproduce

group

species

An organism is a (1) ..................... thing. A (2) ..................... is a group of living organisims that can (3) ..................... with each other to produce (4) ..................... offspring.

Each species of organism has a two-word name. This system of naming is called the (5) ..................... system. The first of the two words in the name tells us the (6) ..................... that the species belongs to.

DEFINE THESE TERMS Write your own definition for the following key terms: •

species

•

genus

5

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

1 Characteristics and classifications of living organisms

1.3 Keys

2 Tigers, Panthera tigris, and lions, Panthera leo, sometimes mate with each other if they are kept together in a zoo. The offspring are called ligers. Ligers are perfectly healthy, but are unable to reproduce. a b

one piece of evidence that lions and tigers are closely related two pieces of evidence that lions and tigers belong to different species.

1

TI AL

Applying your knowledge in lots of different ways helps to store it in your memory.

In this section you will answer a few questions on the same topic - keys - to reinforce your knowledge of it.

Use this information to write down:

Figure 1.3 shows four vertebrates.

A

B

The next question asks you to respond to two command words: describe and explain.

Think about the difference between these two words in your respective answers.

All living organisms are classified into five kingdoms. These include the plant, animal and fungus kingdoms.

Name the other kingdoms.

Describe two ways in which the cells of fungi differ from those of plants.

Figure 1.2 shows a virus.

FI D

a b c

EN

3

O

Figure 1.2: A virus.

Name parts X and Y. Explain why viruses are not generally classified into any of the five kingdoms.

C

i ii

Write your own definition for the following key terms: •

vertebrate

•

anthropod

TIP

D

Remember to work on one animal at a time. Identify that one, then move onto the next.

N

C

DEFINE THESE TERMS

Now write down what you will do to strengthen your learning for these areas (for example, read Coursebook section 1.2 and then explain it to a friend or parent).

D

R

AF

How you will check that you have increased your understanding? For example, you could answer question X at the end of this chapter. Once you have done this, return here and make a note about how successful your re-learning method was. If it was successful, you can use it for other areas where you are less confident. If not, try another method next time – perhaps speaking to your teacher, or finding more questions to practise. It’s important to discover what methods work for you

T

How confident did you feel answering the questions in this section? Are there any areas that you felt unsure about? Write them down.

&

REFLECTION

QUICK RECALL 2: SUBJECT KNOWLEDGE

Figure 1.3: Four vertebrates.

Use the dichotomous key to identify each of these four animals.

List the sequence of statements that you worked through to find the name.

TIP 1 2 3

a

shell present ...................................... Geochelone elephantopus

b

shell absent ...................................... go to 2

a

four legs ...................................... go to 3

b

no legs ...................................... Ophiophagus hannah

a

back and tail are covered with rough spikes ......................................

Crocodylus niloticus

b

no spikes on tail ...................................... Chamaeleo gracilis

When writing binomials, underline them to show that they should be in italics. Remember that the genus name starts with a capital letter but the species name is all lowercase.

Animal A has been done for you: A 1b, 2a, 3a – Crocodylus niloticus

List the seven characteristics of living things.

6

7

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

1 Characteristics and classifications of living organisms

1.3 Keys

2 Tigers, Panthera tigris, and lions, Panthera leo, sometimes mate with each other if they are kept together in a zoo. The offspring are called ligers. Ligers are perfectly healthy, but are unable to reproduce. a b

one piece of evidence that lions and tigers are closely related two pieces of evidence that lions and tigers belong to different species.

1

TI AL

Applying your knowledge in lots of different ways helps to store it in your memory.

In this section you will answer a few questions on the same topic - keys - to reinforce your knowledge of it.

Use this information to write down:

Figure 1.3 shows four vertebrates.

A

B

The next question asks you to respond to two command words: describe and explain.

Think about the difference between these two words in your respective answers.

All living organisms are classified into five kingdoms. These include the plant, animal and fungus kingdoms.

Name the other kingdoms.

Describe two ways in which the cells of fungi differ from those of plants.

Figure 1.2 shows a virus.

FI D

a b c

EN

3

O

Figure 1.2: A virus.

Name parts X and Y. Explain why viruses are not generally classified into any of the five kingdoms.

C

i ii

Write your own definition for the following key terms: •

vertebrate

•

anthropod

TIP

D

Remember to work on one animal at a time. Identify that one, then move onto the next.

N

C

DEFINE THESE TERMS

Now write down what you will do to strengthen your learning for these areas (for example, read Coursebook section 1.2 and then explain it to a friend or parent).

D

R

AF

How you will check that you have increased your understanding? For example, you could answer question X at the end of this chapter. Once you have done this, return here and make a note about how successful your re-learning method was. If it was successful, you can use it for other areas where you are less confident. If not, try another method next time – perhaps speaking to your teacher, or finding more questions to practise. It’s important to discover what methods work for you

T

How confident did you feel answering the questions in this section? Are there any areas that you felt unsure about? Write them down.

&

REFLECTION

QUICK RECALL 2: SUBJECT KNOWLEDGE

Figure 1.3: Four vertebrates.

Use the dichotomous key to identify each of these four animals.

List the sequence of statements that you worked through to find the name.

TIP 1 2 3

a

shell present ...................................... Geochelone elephantopus

b

shell absent ...................................... go to 2

a

four legs ...................................... go to 3

b

no legs ...................................... Ophiophagus hannah

a

back and tail are covered with rough spikes ......................................

Crocodylus niloticus

b

no spikes on tail ...................................... Chamaeleo gracilis

When writing binomials, underline them to show that they should be in italics. Remember that the genus name starts with a capital letter but the species name is all lowercase.

Animal A has been done for you: A 1b, 2a, 3a – Crocodylus niloticus

List the seven characteristics of living things.

6

7

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2

1 Characteristics and classifications of living organisms

Figure 1.4 shows a spider, locust, centipede and crab.

SELF-ASSESSMENT How confident do you feel about using and writing keys?

Rate yourself for each of the points in the checklist using: if you did it really well

TI AL

  

if you made an attempt at it and partly succeeded if you did not try to do it, or did not succeed:

Checklist

Rating

I can use a dichotomous key to identify organisms.

EN

I can complete a key that has already been started.

I can write my own key with no help.

Figure 1.4: Spider, locust, centipede and crab.

Here is the start of a key to help someone who does not know anything about these animals to identify them. Complete the key by writing more pairs of statements.

Then try out your key on a friend.

What will you do to improve your ability to write a good dichotomous key?

FI D

QUICK RECALL 3: SUBJECT KNOWLEDGE

has antennae ...................................... go to 2

b

does not have antennae ...................................... spider

2

a

has three pairs of legs ......................................

O

a

C

Figure 1.5 shows photographs of four species of fish.

Explain what this tells us about the groups into which yaks are classified.

EXAM READY! Write down the command words in all of the questions in this chapter. Then write down what each one means.

Now go back and read your answers. Have you fulfilled each of the command terms? If not, do this now to improve your answers.

Figure 1.5: Spider, locust, centipede and crab.

8

D

R

AF

T

&

3

1

N

Yaks have the scientific name Bos grunniens.

Write a dichotomous key to enable someone to identify each of the four fish.

9

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2

1 Characteristics and classifications of living organisms

Figure 1.4 shows a spider, locust, centipede and crab.

SELF-ASSESSMENT How confident do you feel about using and writing keys?

Rate yourself for each of the points in the checklist using: if you did it really well

TI AL

  

if you made an attempt at it and partly succeeded if you did not try to do it, or did not succeed:

Checklist

Rating

I can use a dichotomous key to identify organisms.

EN

I can complete a key that has already been started.

I can write my own key with no help.

Figure 1.4: Spider, locust, centipede and crab.

Here is the start of a key to help someone who does not know anything about these animals to identify them. Complete the key by writing more pairs of statements.

Then try out your key on a friend.

What will you do to improve your ability to write a good dichotomous key?

FI D

QUICK RECALL 3: SUBJECT KNOWLEDGE

has antennae ...................................... go to 2

b

does not have antennae ...................................... spider

2

a

has three pairs of legs ......................................

O

a

C

Figure 1.5 shows photographs of four species of fish.

Explain what this tells us about the groups into which yaks are classified.

EXAM READY! Write down the command words in all of the questions in this chapter. Then write down what each one means.

Now go back and read your answers. Have you fulfilled each of the command terms? If not, do this now to improve your answers.

Figure 1.5: Spider, locust, centipede and crab.

8

D

R

AF

T

&

3

1

N

Yaks have the scientific name Bos grunniens.

Write a dichotomous key to enable someone to identify each of the four fish.

9

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

SELF-EVALUATION CHECKLIST

2 Cells

Needs more work

Almost there

TI AL

Let’s revisit the learning objectives and exam skills objectives for this chapter.

Decide how confident you are with each statement.

Confident to move on

recall and describe the seven characteristics of living things

In this chapter you will check that you know the key concepts of cells and practice how you show this knowledge in an exam.

use the binomial system to name organisms

Answering questions and testing your knowledge is very important for your memory. Every time you recall information and write an answer, your knowledge and understanding gets stronger. Once you have consolidated your memory, you can better concentrate on what in particular the exam question is asking you to do.

use and construct keys

EN

classify vertebrates and arthropods show that you understand the ‘describe’ command word and answer a ‘describe’ question.

Exam questions are very specific and are looking for certain things, so you need to be ready for the approach that they take so that you can really show what you know.

FI D

think about your learning and identify any areas where you might need some more support

For that reason, there are three kinds of question in this chapter.

plan how to address these areas, try it out, and reflect on how successful it was What will you do to work on the topics that you are not yet ready to move on from?

N

Once you are confident to move on, complete the table below.

Show it

recall and describe the seven characteristics of living things

Describe two of the characteristics of living things

use the binomial system to name organisms

Identify that genus that Okapia johnstoni belongs to.

use and construct keys

Choose three organisms and construct a key for them.

classify vertebrates and arthropods

Give one example of a vertebrate and one example of an arthropod.

show that I understand the ‘describe’ command word and answer a ‘describe’ question.

What does ‘describe’ mean?

think about my learning and identify any areas where I might need some more support plan how to address these areas, try it out, and reflect on how successful it was

&

C

O

Now I can

1

Knowledge recall questions: Questions that increase your memory of what you know about cells

2

Exam skills questions: Questions that practice showing what you know about cells in an exam

3

Self assessment questions: Questions that help you monitor your own progress

You will also find questions about the characteristics and classification of living organisms. This is because your memory is best increased by a technique called interleaving. This is when you return to a previously studied topic within a certain timeframe to make sure that you remember it properly.

LEARNING OBJECTIVES In this chapter, you will: find out about the structure of the cells of animals, plants and bacteria

•

learn about the functions of each of the parts of these cells

List any areas of you have identified as needing support.

•

describe how the structures of some specialised cells are related to their functions

List one thing you did, and how you found it.

•

practise using the magnification equation

D

R

AF

T

•

10

11

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

SELF-EVALUATION CHECKLIST

2 Cells

Needs more work

Almost there

TI AL

Let’s revisit the learning objectives and exam skills objectives for this chapter.

Decide how confident you are with each statement.

Confident to move on

recall and describe the seven characteristics of living things

In this chapter you will check that you know the key concepts of cells and practice how you show this knowledge in an exam.

use the binomial system to name organisms

Answering questions and testing your knowledge is very important for your memory. Every time you recall information and write an answer, your knowledge and understanding gets stronger. Once you have consolidated your memory, you can better concentrate on what in particular the exam question is asking you to do.

use and construct keys

EN

classify vertebrates and arthropods show that you understand the ‘describe’ command word and answer a ‘describe’ question.

Exam questions are very specific and are looking for certain things, so you need to be ready for the approach that they take so that you can really show what you know.

FI D

think about your learning and identify any areas where you might need some more support

For that reason, there are three kinds of question in this chapter.

plan how to address these areas, try it out, and reflect on how successful it was What will you do to work on the topics that you are not yet ready to move on from?

N

Once you are confident to move on, complete the table below.

Show it

recall and describe the seven characteristics of living things

Describe two of the characteristics of living things

use the binomial system to name organisms

Identify that genus that Okapia johnstoni belongs to.

use and construct keys

Choose three organisms and construct a key for them.

classify vertebrates and arthropods

Give one example of a vertebrate and one example of an arthropod.

show that I understand the ‘describe’ command word and answer a ‘describe’ question.

What does ‘describe’ mean?

think about my learning and identify any areas where I might need some more support plan how to address these areas, try it out, and reflect on how successful it was

&

C

O

Now I can

1

Knowledge recall questions: Questions that increase your memory of what you know about cells

2

Exam skills questions: Questions that practice showing what you know about cells in an exam

3

Self assessment questions: Questions that help you monitor your own progress

You will also find questions about the characteristics and classification of living organisms. This is because your memory is best increased by a technique called interleaving. This is when you return to a previously studied topic within a certain timeframe to make sure that you remember it properly.

LEARNING OBJECTIVES In this chapter, you will: find out about the structure of the cells of animals, plants and bacteria

•

learn about the functions of each of the parts of these cells

List any areas of you have identified as needing support.

•

describe how the structures of some specialised cells are related to their functions

List one thing you did, and how you found it.

•

practise using the magnification equation

D

R

AF

T

•

10

11

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

2.0 Exam skills

Providing a response to an exam question

For every exam, you will know the duration in advance. For example:

Writing to time

•

Paper 1 (core) is a multiple-choice paper lasting 45 minutes.

There are 40 multiple-choice questions and a total of 45 marks.

•

Paper 1 (extended) is a multiple-choice paper lasting 45 minutes.

There are 40 multiple-choice questions and a total of 80 marks.

To help you prepare for your exams, this book guides you through a framework of exam skills that will help you to show what you know about Biology in the Cambridge exam context; from the various elements of understanding the question, to writing a good response, to developing the kind of behaviours and habits that will support you along the way.

TI AL

Getting exam ready

Which paper will you be taking?

It is important to plan your time so that you can:

Alongside recalling your knowledge on cells, in this chapter you will also practice writing to time. The relevant part of the Cambridge Exam Skills Framework is as follows:

read the exam paper instructions carefully

EN

•

read and answer all questions

Extract from the Cambridge Exam Skills Framework

•

perform a quick check over your answers to make sure that you haven’t missed any

Exam skill

Providing a response to an exam question

Sub-skill

Writing to time

Objectives

• • •

If you were taking Paper 1, you might allocate 3 minutes to reading the exam paper instructions and 2 minutes to checking your answers. This would leave you with 40 minutes to answer the 40 questions – one minute per question. This is not to give you a strict limit to stick to, but to give you an idea of what to aim for.

FI D

•

Convey key information in the time available.

Distribute your time appropriately across the exam paper.

Allow time to check your response.

O

N

In this chapter you are going to practice how to use your time in an exam wisely so that you can answer all the questions sufficiently and show what you know to the best of your ability.

EXAM SKILLS OBJECTIVES practise identifying how much time to spend on questions in an examination

•

practise writing to time

2.1 Animals, plants and bacteria 1

Figure 2.1 shows an animal cell and the outline of a plant cell.

D

R

AF

T

&

•

C

In this chapter, you will:

Find out the duration of another paper you will be taking and calculate the amount of time to spend on questions. Note that exam papers do not always include the same number of questions but show a general pattern. If the number of questions is not specified, have a look at some past papers to work out a rough idea.

12

DEFINE THESE TERMS Write your own definition for the following key terms:

Figure 2.1 a: An animal cell. b: A plant cell. a

Copy the animal cell diagram and label these parts: cell membrane

cytoplasm

mitochondrion

nucleus

•

cell membrane

•

cell wall

•

nucleus

13

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

2.0 Exam skills

Providing a response to an exam question

For every exam, you will know the duration in advance. For example:

Writing to time

•

Paper 1 (core) is a multiple-choice paper lasting 45 minutes.

There are 40 multiple-choice questions and a total of 45 marks.

•

Paper 1 (extended) is a multiple-choice paper lasting 45 minutes.

There are 40 multiple-choice questions and a total of 80 marks.

To help you prepare for your exams, this book guides you through a framework of exam skills that will help you to show what you know about Biology in the Cambridge exam context; from the various elements of understanding the question, to writing a good response, to developing the kind of behaviours and habits that will support you along the way.

TI AL

Getting exam ready

Which paper will you be taking?

It is important to plan your time so that you can:

Alongside recalling your knowledge on cells, in this chapter you will also practice writing to time. The relevant part of the Cambridge Exam Skills Framework is as follows:

read the exam paper instructions carefully

EN

•

read and answer all questions

Extract from the Cambridge Exam Skills Framework

•

perform a quick check over your answers to make sure that you haven’t missed any

Exam skill

Providing a response to an exam question

Sub-skill

Writing to time

Objectives

• • •

If you were taking Paper 1, you might allocate 3 minutes to reading the exam paper instructions and 2 minutes to checking your answers. This would leave you with 40 minutes to answer the 40 questions – one minute per question. This is not to give you a strict limit to stick to, but to give you an idea of what to aim for.

FI D

•

Convey key information in the time available.

Distribute your time appropriately across the exam paper.

Allow time to check your response.

O

N

In this chapter you are going to practice how to use your time in an exam wisely so that you can answer all the questions sufficiently and show what you know to the best of your ability.

EXAM SKILLS OBJECTIVES practise identifying how much time to spend on questions in an examination

•

practise writing to time

2.1 Animals, plants and bacteria 1

Figure 2.1 shows an animal cell and the outline of a plant cell.

D

R

AF

T

&

•

C

In this chapter, you will:

Find out the duration of another paper you will be taking and calculate the amount of time to spend on questions. Note that exam papers do not always include the same number of questions but show a general pattern. If the number of questions is not specified, have a look at some past papers to work out a rough idea.

12

DEFINE THESE TERMS Write your own definition for the following key terms:

Figure 2.1 a: An animal cell. b: A plant cell. a

Copy the animal cell diagram and label these parts: cell membrane

cytoplasm

mitochondrion

nucleus

•

cell membrane

•

cell wall

•

nucleus

13

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

Copy and complete the diagram of the plant cell, and then label these parts: cell membrane vacuole

cell wall

containing cell sap mitochondrion

chloroplast

CONTINUED Peer assessment

cytoplasm

membrane around vacuole nucleus

SELF-ASSESSMENT How confident do you feel about drawing a plant cell? Give yourself a mark for each of the points in the checklist. Award yourself: if you did it well

1 mark

if you made a good attempt at it and partly succeeded

0 marks

if you did not try to do it, or did not succeed

N

I did not use any shading or colours.

O

I drew the parts of the cell in the right place (check against Figure 2.3, Chapter 2 in the Coursebook) I drew label lines with a ruler

C

Each label line touches the part it is labelling.

Working with a partner or in a group helps to reinforce your learning. You can work with others on the following activities and see how your understanding develops.

On your large sheet of paper, make a drawing of a plant cell. You could copy the one in Figure 2.X. Leave plenty of space around your drawing.

2

Use the information in the coursebook chapter to find one part of the cell – e.g. the cell wall.

a pencil, marker pens and a ruler.

4

14

R

3

AF

1

Draw a label line, using a ruler, to this part of the cell. Write the name of the part, and then a short summary of what it does.

D

•

a large sheet of paper, at least A4 and larger if possible

T

ACTIVITY 2.1

&

Total (out of 12):

•

•

whether the drawing is as large and clear as possible

Green if they did it really well

•

how well they have described the function of each part.

How will you try to learn the names of the parts of animal, plant and bacterial cells, and their functions? Think about which of these ideas might work for you:

I drew single clean lines; the lines are not broken or fuzzy.

You will need:

Rate them a mark according to the following scheme.

REFLECTION

Marks awarded

You could work on your own or in a pair for this activity.

You could think about:

Amber if they made a good attempt at it and partly succeeded

I used a sharp pencil for drawing.

Functions on the parts of a plant cell

Look at your partner’s diagram and assess how well they have carried out the task.

if they did not try to do it, or did not succeed

FI D

Checklist

Red

EN

2 marks

Exchange your diagram with a partner.

TI AL

b

2 Cells

•

looking at diagrams and reading about the structures

•

practising drawing your own diagrams and labelling them

•

getting a friend to test you by asking questions

•

making some revision cards for yourself, with the name of a structure on one side and its function on the other side

What other ideas might you try?

GROUP PROJECT Making a model cell It is best to work in a group of three or four for this project.

Discuss different ideas about how you can make a model cell. What kind of cell will it be – an animal cell, a plant cell or a bacterial cell?

How can you construct your cell? What materials will you need?

If you are short of ideas, you could search on the internet. However, even if you do find some good suggestions there, it is important to make the model cell your own, using some of your own ideas that make it different from everyone else’s models.

As you build your model, you will almost certainly make some changes to your original plans, so be prepared to source some extra materials as you work.

After you have completed your model, you can compare it with the models that other groups have made. This might give you ideas about how you could make an even better model if you did it again.

Repeat steps 2 and 3 for each part of the cell.

15

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

Copy and complete the diagram of the plant cell, and then label these parts: cell membrane vacuole

cell wall

containing cell sap mitochondrion

chloroplast

CONTINUED Peer assessment

cytoplasm

membrane around vacuole nucleus

SELF-ASSESSMENT How confident do you feel about drawing a plant cell? Give yourself a mark for each of the points in the checklist. Award yourself: if you did it well

1 mark

if you made a good attempt at it and partly succeeded

0 marks

if you did not try to do it, or did not succeed

N

I did not use any shading or colours.

O

I drew the parts of the cell in the right place (check against Figure 2.3, Chapter 2 in the Coursebook) I drew label lines with a ruler

C

Each label line touches the part it is labelling.

Working with a partner or in a group helps to reinforce your learning. You can work with others on the following activities and see how your understanding develops.

On your large sheet of paper, make a drawing of a plant cell. You could copy the one in Figure 2.X. Leave plenty of space around your drawing.

2

Use the information in the coursebook chapter to find one part of the cell – e.g. the cell wall.

a pencil, marker pens and a ruler.

4

14

R

3

AF

1

Draw a label line, using a ruler, to this part of the cell. Write the name of the part, and then a short summary of what it does.

D

•

a large sheet of paper, at least A4 and larger if possible

T

ACTIVITY 2.1

&

Total (out of 12):

•

•

whether the drawing is as large and clear as possible

Green if they did it really well

•

how well they have described the function of each part.

How will you try to learn the names of the parts of animal, plant and bacterial cells, and their functions? Think about which of these ideas might work for you:

I drew single clean lines; the lines are not broken or fuzzy.

You will need:

Rate them a mark according to the following scheme.

REFLECTION

Marks awarded

You could work on your own or in a pair for this activity.

You could think about:

Amber if they made a good attempt at it and partly succeeded

I used a sharp pencil for drawing.

Functions on the parts of a plant cell

Look at your partner’s diagram and assess how well they have carried out the task.

if they did not try to do it, or did not succeed

FI D

Checklist

Red

EN

2 marks

Exchange your diagram with a partner.

TI AL

b

2 Cells

•

looking at diagrams and reading about the structures

•

practising drawing your own diagrams and labelling them

•

getting a friend to test you by asking questions

•

making some revision cards for yourself, with the name of a structure on one side and its function on the other side

What other ideas might you try?

GROUP PROJECT Making a model cell It is best to work in a group of three or four for this project.

Discuss different ideas about how you can make a model cell. What kind of cell will it be – an animal cell, a plant cell or a bacterial cell?

How can you construct your cell? What materials will you need?

If you are short of ideas, you could search on the internet. However, even if you do find some good suggestions there, it is important to make the model cell your own, using some of your own ideas that make it different from everyone else’s models.

As you build your model, you will almost certainly make some changes to your original plans, so be prepared to source some extra materials as you work.

After you have completed your model, you can compare it with the models that other groups have made. This might give you ideas about how you could make an even better model if you did it again.

Repeat steps 2 and 3 for each part of the cell.

15

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

2.2 Specialised cells and sizes of specimens

Before you answer the following questions, work out how long to spend on each of them. Assume you have a maximum of 3 minutes for the three questions. Then set a timer for each question and see whether you answer them within this time. (The aim is not to be as quick as possible, but to become familiar with the expected duration.)

Figure 2.2 shows a cell from a plant leaf.

Practising using the magnification equation

TI AL

2

ACTIVITY 2.2

Work on your own for the first part of this activity, and then pair up with someone else for the second part.

You will need:

magnification

several small objects that are easy to measure and draw – for example, an eraser, a paper clip, a button

•

a ruler that can measure in mm

•

some plain paper, a good pencil and an eraser.

Which labelled part contains DNA?

3

Which structure is found in both animal and bacterial cells?

FI D

A B C D

O C &

1

Measure each object carefully and write down the measurements.

Don’t let anyone else see these measurements at this point.

2

Make a magnified drawing of your objects. Calculate the magnification of each one and write it next to your drawings. Try to use different magnifications for each object. (You could even try drawing some objects smaller than they really are, so that the magnification is less than 1.)

Second part – work with a partner 3

Exchange your drawings with a partner. Each of you uses the drawings and magnifications to work out the size of the actual object.

4

Check your answers with your partner – did you correctly calculate the actual sizes of the objects they had drawn? Did your partner calculate the actual sizes of the objects that you had drawn.

Self assessment Did you calculate the magnifications of your drawings correctly, so that your partner could work out the actual size of each drawing.

If not, where did you go wrong?

Were you able to calculate the actual size of the objects your partner had drawn? If not, where did you (or they) go wrong?

D

R

AF

T

3.2 mm 20 mm 0.5 cm 32 cm

N

cell membrane cytoplasm mitochondrion ribosome

A diagram of a flower is 8 cm across. The magnification of the diagram is x4.

What is the actual width of the flower?

A B C D

•

First part – work on your own for this

Figure 2.2: A cell from a leaf plant.

4

Write your own definition for the following key term:

EN

•

DEFINE THESE TERMS

16

17

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

2.2 Specialised cells and sizes of specimens

Before you answer the following questions, work out how long to spend on each of them. Assume you have a maximum of 3 minutes for the three questions. Then set a timer for each question and see whether you answer them within this time. (The aim is not to be as quick as possible, but to become familiar with the expected duration.)

Figure 2.2 shows a cell from a plant leaf.

Practising using the magnification equation

TI AL

2

ACTIVITY 2.2

Work on your own for the first part of this activity, and then pair up with someone else for the second part.

You will need:

magnification

several small objects that are easy to measure and draw – for example, an eraser, a paper clip, a button

•

a ruler that can measure in mm

•

some plain paper, a good pencil and an eraser.

Which labelled part contains DNA?

3

Which structure is found in both animal and bacterial cells?

FI D

A B C D

O C &

1

Measure each object carefully and write down the measurements.

Don’t let anyone else see these measurements at this point.

2

Make a magnified drawing of your objects. Calculate the magnification of each one and write it next to your drawings. Try to use different magnifications for each object. (You could even try drawing some objects smaller than they really are, so that the magnification is less than 1.)

Second part – work with a partner 3

Exchange your drawings with a partner. Each of you uses the drawings and magnifications to work out the size of the actual object.

4

Check your answers with your partner – did you correctly calculate the actual sizes of the objects they had drawn? Did your partner calculate the actual sizes of the objects that you had drawn.

Self assessment Did you calculate the magnifications of your drawings correctly, so that your partner could work out the actual size of each drawing.

If not, where did you go wrong?

Were you able to calculate the actual size of the objects your partner had drawn? If not, where did you (or they) go wrong?

D

R

AF

T

3.2 mm 20 mm 0.5 cm 32 cm

N

cell membrane cytoplasm mitochondrion ribosome

A diagram of a flower is 8 cm across. The magnification of the diagram is x4.

What is the actual width of the flower?

A B C D

•

First part – work on your own for this

Figure 2.2: A cell from a leaf plant.

4

Write your own definition for the following key term:

EN

•

DEFINE THESE TERMS

16

17

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

Figure 2.3 shows a leaf.

1

Figure 2.3: A leaf.

TIP

Measure the length of the leaf in Figure 2.x. Write down your answer.

2

Calculate the magnification of the leaf image in Figure 2.x.

Show your working. Give your answer to one decimal place.

It is always best to measure in millimetres (mm). Remember to write the unit when you write down your measurement.

QUICK RECALL 1: SUBJECT KNOWLEDGE

Calculate the magnification of the diagram.

Show your working and give your answer to two decimal places.

b

Outline the function of each of these parts of a plant cell. i the nucleus

[2]

ii ribosomes

[2] [Total: 7]

2

Figure 2.5 is a photograph of a jellyfish. A jellyfish belongs to the animal kingdom.

Figure 2.5: A jellyfish.

AF R D 18

Figure 2.4: Plant cells through a light microscope.

&

The actual length of this animal is 105 mm.

[1]

T

b

iii Name one cell structure that these cells do not contain,

which you would expect to find in a palisade cell.

C

Look at the diagram of animal D in Chapter 1, Figure 1.2.

Measure the length of animal D from its nose to the base of its tail.

[1] [1]

O

You have already studied animals in Chapter 1. There will be times in your studies when you need to measure diagrams of entire animals, not just cells. a

State one way you can tell that these are plant cells and not animal cells.

State one way you can tell that these are not bacterial cells.

FI D

1

a i

ii

N

The actual length of the leaf is 32 mm.

Figure 2.4 is a photograph taken through a light microscope.

It shows a group of plant cells.

EN

TI AL

The following questions contain the command words state, outline and calculate.

Note the difference between the number of marks allocated for each question.

If the marks are higher, this means that the command word requires you to show evidence of more advanced thinking, which usually takes longer to work out.

Make sure that you allow plenty of time to answer these higher mark questions.

ACTIVITY 2.3

a b c

The actual jellyfish is 50 mm in diameter.

Calculate the magnification of the photograph.

[3] Name three parts that you would find in a cell in a jellyfish and outline the function of each part.

[6] Some of the cells in the jellyfish are neurones.

State the function of a neurone.

[1] [Total: 10]

19

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

2 Cells

Figure 2.3 shows a leaf.

1

Figure 2.3: A leaf.

TIP

Measure the length of the leaf in Figure 2.x. Write down your answer.

2

Calculate the magnification of the leaf image in Figure 2.x.

Show your working. Give your answer to one decimal place.

It is always best to measure in millimetres (mm). Remember to write the unit when you write down your measurement.

QUICK RECALL 1: SUBJECT KNOWLEDGE

Calculate the magnification of the diagram.

Show your working and give your answer to two decimal places.

b

Outline the function of each of these parts of a plant cell. i the nucleus

[2]

ii ribosomes

[2] [Total: 7]

2

Figure 2.5 is a photograph of a jellyfish. A jellyfish belongs to the animal kingdom.

Figure 2.5: A jellyfish.

AF R D 18

Figure 2.4: Plant cells through a light microscope.

&

The actual length of this animal is 105 mm.

[1]

T

b

iii Name one cell structure that these cells do not contain,

which you would expect to find in a palisade cell.

C

Look at the diagram of animal D in Chapter 1, Figure 1.2.

Measure the length of animal D from its nose to the base of its tail.

[1] [1]

O

You have already studied animals in Chapter 1. There will be times in your studies when you need to measure diagrams of entire animals, not just cells. a

State one way you can tell that these are plant cells and not animal cells.

State one way you can tell that these are not bacterial cells.

FI D

1

a i

ii

N

The actual length of the leaf is 32 mm.

Figure 2.4 is a photograph taken through a light microscope.

It shows a group of plant cells.

EN

TI AL

The following questions contain the command words state, outline and calculate.

Note the difference between the number of marks allocated for each question.

If the marks are higher, this means that the command word requires you to show evidence of more advanced thinking, which usually takes longer to work out.

Make sure that you allow plenty of time to answer these higher mark questions.

ACTIVITY 2.3

a b c

The actual jellyfish is 50 mm in diameter.

Calculate the magnification of the photograph.

[3] Name three parts that you would find in a cell in a jellyfish and outline the function of each part.

[6] Some of the cells in the jellyfish are neurones.

State the function of a neurone.

[1] [Total: 10]

19

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

3

2 Cells

Figure 2.6 is an electron micrograph of a small part of a cell from the pancreas.

This cell makes large quantities of protein molecules, which are stored in vesicles before being exported from the cell.

SELF-EVALUATION CHECKLIST

TI AL

Let’s revisit the learning objectives and exam skills objectives for this chapter.

Decide how confident you are with each statement.

Needs more work

Almost there

Confident to move on

find out about the structure of the cells of animals, plants and bacteria learn about the functions of each of the parts of these cells

EN

describe how the structures of some specialised cells are related to their functions practise using the magnification equation

FI D

practise identifying how much time to spend on questions in an examination practise writing to time

What will you do to work on the topics that you are not yet ready to move on from?

O

N

Once you are confident to move on, complete the table below.

b

Structure A contains molecules that determine the type of proteins made in the cell. Identify structure A. [1] Use the information above to explain why the cell has large numbers of structures B and C. [6]

[Total: 7]

T

EXAM READY!

&

a

C

Figure 2.6: A jellyfish.

Write down the command words in the questions above.

•

Then write down what each one means.

•

Now go back and read your answers. Have you fulfilled each of the command terms? If not, do this now to improve your answers. .

Show it

Describe and compare the structure of different cells.

State the differences between an animal cell and plant cell.

Describe the function of cell structures.

Name five cell structures and explain what they do.

Identify the parts of cells in diagrams.

Draw a labelled diagram of an animal cell.

Name some specialised cells and their functions.

Give three examples of tissues and describe their functions.

Calculate magnifications using the magnification equation.

Use the magnification equation to …

Convert measurements.

Convert X into Y …

Identify how much time to spend on questions in an examination and write to time.

Look at an IGCSE Science paper and work out how much time you would spend on each question.

D

R

AF

•

Now I

20

21

CAMBRIDGE IGCSE BIOLOGY: REVISION GUIDE

3

2 Cells

Figure 2.6 is an electron micrograph of a small part of a cell from the pancreas.

This cell makes large quantities of protein molecules, which are stored in vesicles before being exported from the cell.

SELF-EVALUATION CHECKLIST

TI AL

Let’s revisit the learning objectives and exam skills objectives for this chapter.

Decide how confident you are with each statement.

Needs more work

Almost there

Confident to move on

find out about the structure of the cells of animals, plants and bacteria learn about the functions of each of the parts of these cells

EN

describe how the structures of some specialised cells are related to their functions practise using the magnification equation

FI D

practise identifying how much time to spend on questions in an examination practise writing to time

What will you do to work on the topics that you are not yet ready to move on from?

O

N

Once you are confident to move on, complete the table below.

b

Structure A contains molecules that determine the type of proteins made in the cell. Identify structure A. [1] Use the information above to explain why the cell has large numbers of structures B and C. [6]

[Total: 7]

T

EXAM READY!

&

a

C

Figure 2.6: A jellyfish.

Write down the command words in the questions above.

•

Then write down what each one means.

•

Now go back and read your answers. Have you fulfilled each of the command terms? If not, do this now to improve your answers. .

Show it

Describe and compare the structure of different cells.

State the differences between an animal cell and plant cell.

Describe the function of cell structures.

Name five cell structures and explain what they do.

Identify the parts of cells in diagrams.

Draw a labelled diagram of an animal cell.

Name some specialised cells and their functions.

Give three examples of tissues and describe their functions.

Calculate magnifications using the magnification equation.

Use the magnification equation to …

Convert measurements.

Convert X into Y …

Identify how much time to spend on questions in an examination and write to time.

Look at an IGCSE Science paper and work out how much time you would spend on each question.

D

R

AF

•

Now I

20

21