Edexcel International GCSE
Biology Sue Kearsey
Teacher Pack
Contents Introduction
5
Suggested teaching sequence
7
Matching chart to Double and Single awards
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Section 1: The nature and variety of living organisms 13 B1a) Characteristics of living organisms B1a.1 The eight characteristics of life B1a.2 Consolidation and summary B1b) Variety of living organisms B1b.1 Classifying organisms B1b.2 Consolidation and summary Answers to exam-style questions
14 15 19 21 22 26 28
B2h.2 Blood B2h.3 The human circulatory system B2h.4 Consolidation and summary B2i) Excretion B2i.1 Excretion in organisms B2i.2 Producing urine B2i.3 Osmoregulation B2i.4 Consolidation and summary B2j) Coordination and response B2j.1 Plant tropisms B2j.2 Human nervous system B2j.3 Homeostasis B2j.4 Human hormonal system B2j.5 Consolidation and summary Answers to exam-style questions
141 143 147 149 150 152 156 158 160 161 167 173 177 179 182
Section 3: Reproduction and inheritance 188 Section 2: Structures and functions in living organisms 29 B2a) Levels of organisation 31 B2a.1 Levels of organisation within organisms 32 B2a.2 Consolidation and summary 35 B2b) Cell structure 37 B2b.1 Plant and animal cells 38 B2b.2 Consolidation and summary 44 B2c) Biological molecules 46 B2c.1 Food molecules 47 B2c.2 Enzymes 51 B2c.3 Consolidation and summary 58 B2d) Movement of substances into and out of cells 60 B2d.1 Diffusion 61 B2d.2 Osmosis 68 B2d.3 Active transport 78 B2d.4 Consolidation and summary 79 B2e) Nutrition 81 B2e.1 Photosynthesis 82 B2e.2 Mineral nutrients in plants 93 B2e.3 Human nutrition 97 B2e.4 Consolidation and summary 108 B2f) Respiration 111 B2f.1 Respiration 112 B2f.2 Consolidation and summary 116 B2g) Gas exchange 118 B2g.1 Gas exchange in flowering plants 119 B2g.2 Gas exchange in humans 125 B2g.3 Consolidation and summary 132 B2h) Transport 135 B2h.1Transport in flowering plants 136 Edexcel International GCSE Biology Teacher Pack
B3a) Reproduction B3a.1 Sexual and asexual reproduction B3a.2 Pollination in plants B3a.3 Fertilisation and seed formation B3a.4 Seed germination B3a.5 Human reproductive system B3a.6 Human menstrual cycle B3a.7 Development of the human fetus B3a.8 Consolidation and summary B3b) Inheritance B3b.1 The structure of DNA B3b.2 Inheriting characteristics B3b.3 Cell division B3b.4 Variation and mutation B3b.5 Evolution by natural selection B3b.6 Consolidation and summary Answers to exam-style questions
190 192 195 198 201 205 209 211 214 215 217 221 227 231 235 238 241
Section 4: Ecology and the environment 246 B4a) The organism in the environment B4a.1 Ecology and organisms B4a.2 Consolidation and summary B4b) Feeding relationships B4b.1 Trophic levels and food webs B4b.2 Using pyramid diagrams B4b.3 Energy losses in food chains B4b.4 Consolidation and summary B4c) Cycles within ecosystems B4c.1 The water cycle B4c.2 The carbon cycle B4c.3 The nitrogen cycle
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B4c.4 Consolidation and summary B4d) Human influences on the environment B4d.1 Air pollution B4d.2 The greenhouse effect B4d.3 Eutrophication B4d.4 Deforestation B4d.5 Consolidation and summary Answers to exam-style questions
286 287 292 295 299 302 304
Section 5: Use of biological resources
307
B5a) Food production B5a.1 Crop plants B5a.2 Growing microorganisms
309 310 314
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B5a.3 Farming fish 323 B5a.4 Consolidation and summary 325 B5b) Selective breeding 327 B5b.1 Selective breeding 328 B5b.5 Consolidation and summary 333 B5c) Genetic modification 335 B5c.1 The process of genetic modification336 B5c.2 Genetically modified organisms 339 B5c.3 Consolidation and summary 342 B5d) Cloning 344 B5d.1 Micropropagation 345 B5d.2 Cloning mammals 351 B5d.3 Consolidation and summary 355 Answers to exam-style questions 356 Scheme of work
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Section B3 Reproduction and inheritance Contents a) Reproduction b) Inheritance c) Answers to exam-style questions
Overview of the section In this section, students will learn about a range of aspects related to reproduction and inheritance. Topic 3a covers the reproductive systems of flowering plants and humans, applying the general principles of systems and processes from Topics 2a–2d. For plants, this is discussed within the context of pollination, fertilisation and germination. For humans, the structure of the reproductive systems is discussed, before looking at the role of hormones in the menstrual cycle and the development of secondary sexual characteristics. Topic 3b begins with the structure of DNA followed by an introduction to genetics through monohybrid inheritance and the inheritance of sex. The topic continues with the production of new cells by mitosis and meiosis, and the role of mutation and inheritance in producing variation within individuals of the same species. The topic concludes with the role of natural selection in the evolution of species.
Starting points The Student Book provides a ‘section opener’, a double page spread that sets the scene for the students (see pages 186–187). It is structured in this way:
An overview providing details of the areas of study
Ten questions, presented in the same order as key areas of learning within the section, which can be used to introduce each key area
A list of section contents
The questions are intended to provide a structure for introducing the section. 1. How can you produce more plants without using flowers? 2. Why do flowers have to be pollinated before they make seed? 3. Why are some flowers large and brightly coloured and others small and pale? 4. What do seeds need to help them start growing? 5. How do the structures of the male and female human reproductive system support their function? 6. What controls the menstrual cycle every month? 7. What is DNA and what is its structure? 8. How can we predict the inheritance of a characteristic controlled by a gene? 9. Why are there two types of cell division? 10. What is natural selection and how can it bring about evolution? The section opener has two main purposes:
To acknowledge students’ prior learning and to value it To provide a benchmark against which future learning can be compared
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Section B3: Opener
You may use the ten questions or ‘starting points’ in the Student Book in a number of different ways to introduce the section:
You could ask students to consider the questions as an introductory homework task.
Students could divide into groups to share their own ideas and understanding and then report back to the whole class.
Students could access the internet, preferably with a time limit, to find out the information required.
You could use a spider chart or other form of wall chart to summarise the ideas of all the students or groups. The advantage of recording these initial ideas in this way is that you may retain them for reference as the individual topics are developed. In this way, you may readily acknowledge your students’ progress in learning.
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B3a Reproduction Introduction This topic looks at the differences between asexual and sexual reproduction, and then covers reproduction in flowering plants and human reproduction.
Links to other topics Sections
Essential background knowledge
1 The nature and variety of living organisms
1a Characteristics of living organisms
Useful links
1b Variety of living organisms 2 Structures and functions in living organisms
2a Levels of organisation 2b Cell structure 2d Movement of substances into and out of cells 2e Nutrition 2g Gas exchange 2h Transport
3 Reproduction and inheritance
3b Inheritance
4 Ecology and the environment 5 Use of biological resources
5b Selective breeding 5c Genetic modification 5d Cloning
Topic overview B3a.1
Sexual and asexual reproduction This short activity looks at the differences between sexual and asexual reproduction, and sets the context for the rest of the work in this topic. It provides practical work on taking cuttings of plants. (Note: The differences between asexual and sexual reproduction are covered further in Topic 3b in the discussion of mitosis and meiosis. Also, growing plants using tissue culture is covered in Topic 5d.)
B3a.2
Pollination in plants In this activity students will learn how the structure of a flower is adapted to the method of pollination, by wind or by insects. This includes practical work on looking at the structures in a flower.
B3a.3
Fertilisation and seed formation In this activity, students will learn how the female gamete is fertilised after pollination, and how the structures of the ovule develop into the seed and fruit. There is practical work on dissecting seeds to look at their internal structure.
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Topic 3a: Reproduction
B3a.4
Seed germination This activity gives students the opportunity to investigate the conditions in which seeds germinate best, and to find out about the role of food reserves in a seed.
B3a.5
Human reproductive system This activity introduces the structures and function of the organs of the human male and female reproductive system, and the hormones involved in the development of secondary sexual characteristics.
B3a.6
Human menstrual cycle In this activity students learn about the roles of oestrogen and progesterone in controlling the menstrual cycle.
B3a.7
Development of the human fetus In this activity students learn about the role of the placenta in supporting the developing embryo, and how the embryo is protected by the amniotic fluid.
B3a.8
Consolidation and summary This activity provides an opportunity for a quick recap on the ideas encountered in the topic as well as time for the students to answer the End of Topic Questions in the Student Book.
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Topic 3a: Reproduction
Activity B3a.1 Sexual and asexual reproduction Learning objectives
Know the differences between sexual and asexual reproduction Know that plants reproduce asexually by natural and by artificial methods
Learning outcomes
Understand the differences between sexual and asexual reproduction Explain that sexual reproduction is the production of new individuals by the fertilisation of a female gamete by a male gamete Explain that asexual reproduction is the production of new genetically identical individuals from the body cells of a parent organism Understand that there are natural and artificial methods for producing new individuals in plants by asexual reproduction
Common misconceptions Some students confuse reproduction and fertilisation, which makes it difficult for them to understand asexual reproduction. It is important to establish the right definitions for each term at the start.
Resources Student Book pages 189–190 Worksheet B3a.1a Taking plant cuttings Files on CD-ROM: B3a.1a_worksheet, B3a.1a_tech_notes Resources for class practical (see Technician’s notes, following)
Approach 1. Introduction Write the word reproduction in the middle of the board and ask students to suggest related words. Ask how the words should be placed to build a concept map. If students are uncertain or confused, encourage discussion. Consider marking these words with a question mark, so that you may use the map again at the end of the activity to identify what students have learned. 2. Differences Ask students to use pages 189–190 of the Student Book to make notes about the advantages and disadvantages of the two kinds of reproduction. They could then use their notes to produce questions to test each other. If there is time and access to books or the internet, students could research other examples of organisms that use asexual reproduction, and try to explain why it is an advantage for them to do so. 3. Taking cuttings Worksheet B3a.1a gives students the opportunity to take cuttings of a plant. These will need at least three weeks to develop roots, and longer if characteristics are to be measured for comparison. However, these measurements would be useful later for the discussion of the effect of genes and environment on variation in a species for Topic 3b Inheritance. 4. Consolidation: concept map Return to the concept map started in the introduction. Ask students to resolve any question marks on the diagram. They should also suggest any additional words from this activity and how they should be added to the concept map. Edexcel International GCSE Biology Teacher Pack
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Topic 3a: Reproduction
Technician’s notes You will need the following resources for the class practical. Be sure to check the latest safety notes on these resources before proceeding. B3a.1a Taking plant cuttings Many plants are suitable for this investigation, but choose something that grows quickly, such as busy lizzie (Impatiens) or pot geranium (Pelargonium). You may prefer to give students shoots that have already been cut from the plant for step 3 on the worksheet. If so, these must be cut as late as possible before the lesson and kept with their cut ends in water until the lesson. Class practical, per group: healthy mature plant sharp knife or scalpel cutting board rooting hormone small pot with drainage holes, e.g. yoghurt pot with 3 or 4 holes in the base compost: use well-draining compost suitable for cuttings pencil water large transparent plastic bag and tie
Answers Page 190 1. Sexual reproduction
Asexual reproduction
Similarities
produce new individuals
Differences
fusion of male gamete with female gamete
new individuals produced from division of body cell of parent
offspring genetically different from parents and from each other
offspring genetically identical to parent
two parents
only one parent
slower because male and female need to find each other and mate
faster because no search for mate
2. Any suitable example that refers to changing environment where genetic variability in offspring increases chance of survival of offspring that are genetically different to parent. 3. Answer should include: summer not long so asexual reproduction increases numbers more rapidly; summer short period, so variability of environment not as big a problem, so genetic variability would not be an advantage; if parent is feeding well on food plant, the offspring from that parent are equally likely to survive and grow well on that food plant, so variability would be a disadvantage.
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Topic 3a: Reproduction
B3a.1a Taking plant cuttings Plant growers use the natural ability of plants to produce new plants from parts of an old one by taking cuttings. Cuttings can be taken from stems, leaves or roots. The new plants are produced as a result of asexual reproduction, as they grow from body cells of the parent plant. So their cells contain the same genes as the parent.
Apparatus healthy mature plant sharp knife or scalpel cutting board rooting hormone small pot with drainage holes compost pencil water large transparent plastic bag and tie SAFETY INFORMATION Take care when using sharp knives/scalpels.
Method 1. Fill the pot with compost and gently firm the compost so that it doesn't completely fill the pot. 2. Water the compost until there is water coming through the drainage holes at the bottom of the pot. Then leave the pot to drain, so that the compost is wet but not waterlogged. 3. Cut a shoot from the plant that has at least four or five leaves. Remove the bottom few leaves to leave at least two leaves. Then cut across the shoot with a sharp knife at right angles to the shoot. 4. Holding the shoot gently but firmly, dip the cut end into the rooting hormone. 5. Use a pencil to make a hole in the compost and place the shoot into the hole so that the leaves are clear of the compost. Firm the compost around the shoot to hold it in place. 6. Place the pot in the large plastic bag and use the tie to close the bag. 7. Leave the cuttings in a bright place, such as a windowsill for several weeks until the roots have started to develop. Then remove the plastic bag and water the compost to keep it moist but not waterlogged.
Analyse and interpret data 1. Compare the characteristics of the new plant grown from the cutting with those of the parent plant. Explain any similarities and any differences.
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Topic 3a: Reproduction
Activity B3a.2 Pollination in plants Learning objectives
Know the structures in wind-pollinated and insect-pollinated flowers are adapted to their functions in reproduction Understand that pollination of a flower produces a pollen tube that leads to fertilisation, seed and fruit formation
Learning outcomes
Describe the structures of an insect-pollinated and a wind-pollinated flower and explain how each is adapted for pollination Know that pollination must occur before fertilisation can take place
Common misconceptions Many people confuse pollination and fertilisation. It is important for students to be able to distinguish properly between them.
Resources Student Book pages 190–195 Worksheet B3a.2a Flower dissection Files on CD-ROM: B3a.2a_worksheet, B3a_2a_tech_notes Resources for class practical (see Technician’s notes, following)
Approach 1. Introduction Give students one minute to write down three important facts about flowers. They should discuss their facts with another student, and choose together their three most important facts. Take examples from the class to cover the biggest possible range of facts. Make sure at least one fact is related to pollination. Use the opportunity to ask students to distinguish between pollination and fertilisation in plants. If they are not sure, leave this for now but make sure you return to it at the end of the activity. 2. The structure of flowers If possible, provide flowers from wind-pollinated and insect-pollinated plants for students to dissect. Worksheet B3a.2a will help. Students will also need the diagram of flower structure from page 193 of the Student Book. Consider providing a photocopy of this diagram to avoid damage to the books. If there is not enough time for students to dissect a flower of each type, then give one half of the class wind-pollinated flowers and the other half insect-pollinated flowers. Allow time for students to present their results to the other half at the end of the practical work. If practical work is not possible, ask students to research examples on the internet or from books, and to draw one example of each, clearly labelling each diagram to show how it is adapted for its particular mode of pollination. Students could also research the shapes of pollen grains from different plants, to identify if those from wind-pollinated plants differ from those of insect-pollinated plants. 3. The growth of pollen tubes The Practical Biology website offers a method for growing pollen tubes, and a range of project ideas to test. The method uses microscope slides that have been thoroughly cleaned before use. Students will Edexcel International GCSE Biology Teacher Pack
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Topic 3a: Reproduction
then need to use a little more care to keep the liquid drops centred under the microscope objective while the pollen tubes grow. Note that growing pollen tubes is often unsuccessful, due to age of the pollen, species used and what they are grown in, so the website provides a sequence of timed photographs to show how they develop. Students could use these to investigate how quickly the tubes grow and how this might relate to the time that elapses between pollination and fertilisation. (Note: conditions in the flower and in the lab will vary, so the time taken for a pollen tube to grow in the different conditions may also vary.) Alternatively, show students a video clip of pollen tube growth, ideally one that shows time passing. 4. Consolidation: drawings Ask students to sketch a flower with typical features of one type of pollination. They should exchange their sketch with a neighbour. Ask them to identify which type of pollination is involved and then annotate the features that are adaptations for this type of pollination. Next they can discuss the sketch with the student who drew it to identify any other features to annotate.
Technician’s notes You will need the following resources for the class practical. Be sure to check the latest safety notes on these resources before proceeding. B3a.2a Flower structure Offer a selection of flowers, some of which are wind-pollinated and some of which are insect-pollinated, but avoid complex 'flowers', such as daises and dandelions, which consist of a large number of true flowers within one flower head. Class practical, per group: flowers from plants of different species sharp knife or scalpel cutting board hand lens or magnifying glass pencil and paper
Answers Page 193 1. Produces the pollen 2. In pollen grains 3. Stigma where pollen grains attach; style which supports the stigma; ovary which surrounds and protects the ovule, inside which is the female gamete
Page 195 1. Wind-pollinated flowers: usually small; no colour (white); make masses of lightweight pollen 2. The lightweight pollen can be carried far in wind; stamens hang outside the flower so the pollen is more likely to be caught by wind. 3. Insect-pollinated flowers: usually large; may be brightly coloured; produce nectar and sometimes scent; make small amounts of larger pollen grains 4. Scent, nectar (as food), and large petals with bright colours all help to attract insects to the flower. As the insect feeds, they pick up pollen, which is then carried to other flowers. Edexcel International GCSE Biology Teacher Pack
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