1. Characteristics and classification of living organisms

1.1 Characteristics of living organisms

1.2 Concept and uses of classification systems

1.3 Features of organisms

2. Organisation of the organism

2.1 Cell structure

2.2 Size of specimens

3. Movement into and out of cells

3.1 Diffusion

3.2 Osmosis

3.3 Active transport

4. Biological molecules

4.1 Biological molecules

5. Enzymes

5.1 Enzymes

6. Plant nutrition

6.1 Photosynthesis

6.2 Leaf structure

7. Human nutrition

7.1 Diet

7.2 Digestive system

7.3 Physical digestion

7.4 Chemical digestion

7.5 Absorption

8. Transport in plants

8.1 Xylem and phloem

8.2 Water uptake

8.3 Transpiration

8.3.1—Transpiration as the loss of water

8.3.2—Water evaporates from the surfaces

8.3.3—Effects of variation of temperature

8.3.4—Water vapour loss is related

8.3.5—Mechanism by which water moves upwards

8.3.6—Effects on the rate of transpiration

8.3.7—Why wilting occurs

8.4 Translocation

9. Transport in animals

9.1 Circulatory systems

9.2 Heart

9.3 Blood vessels

9.4 Blood

10. Diseases and immunity

10.1 Diseases and immunity

11. Gas exchange in humans

11.1 Gas exchange in humans

12. Respiration

12.1 Respiration

12.2 Aerobic respiration

12.3 Anaerobic respiration

13. Excretion in humans

13.1 Excretion in humans

14. Coordination and response

14.1 Coordination and response

14.2 Sense organs

14.3 Hormones

14.4 Homeostasis

14.5 Tropic responses

15. Drugs

15.1 Drugs

16. Reproduction

16.1 Asexual reproduction

16.2 Sexual reproduction

16.3 Sexual reproduction in plants

16.4 Sexual reproduction in humans

16.5 Sex hormones in humans

16.6 Sexually transmitted infections

17. Inheritance

17.1 Chromosomes, genes and proteins

17.2 Mitosis

17.3 Meiosis

17.4 Monohybrid inheritance

18. Variation and selection

18.1 Variation

18.2 Adaptive features

18.3 Selection

19. Organisms and their environment

19.1 Energy flow

19.2 Food chains and food webs

19.3 Nutrient cycles

19.4 Populations

20. Human influences on ecosystems

20.1 Food supply

20.2 Habitat destruction

20.3 Pollution

20.4 Conservation

21. Biotechnology and genetic modification

21.1 Biotechnology and genetic modification

21.2 Biotechnology

21.3 Genetic modification

IGCSE Biology Extended 8.3.5—Mechanism by which water moves upwards Question Bank

• Explain the mechanism by which water moves upwards in the xylem in terms of a transpiration pull that draws up a column of water molecules, held together by forces of attraction between water molecules

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