iGCSE Biology Section 2 lesson 2

1. iGCSE Biology Section 2 lesson 2

2. Content Section 2 Structures and functions in living organisms a) Levels of organisation b) Cell structure c) Biological molecules d) Movement of substances into and out of cells e) Nutrition f) Respiration g) Gas exchange h) Transport i) Excretion j) Coordination and response

3. Content Flowering plants 2.15 describe the process of photosynthesis and understand its importance in the conversion of light energy to chemical energy 2.16 write the word equation and the balanced chemical symbol equation for photosynthesis 2.17 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis 2.18 describe the structure of a leaf and explain how it is adapted for photosynthesis 2.19 understand that plants require mineral ions for growth and that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids 2.20 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll Lesson 2 e) Nutrition

4. Content Humans 2.21 identify sources and describe functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre as components of the diet 2.22 describe the structures of the human alimentary canal and describe the functions of the mouth, oesophagus, stomach, small intestine, large intestine and pancreas 2.23 understand the processes of ingestion, digestion, absorption, assimilation and egestion 2.24 explain how and why food is moved through the gut by peristalsis 2.25 understand the role of digestive enzymes, to include the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases 2.26 understand that bile is produced by the liver and stored in the gall bladder, and understand the role of bile in neutralising stomach acid and emulsifying lipids Lesson 3 e) Nutrition

5. Flowering plants AUTOTROPHS –organisms that can produce complex organic compounds from simple inorganic molecules. They are the PRODUCERS in a food chain.

6. Flowering plants AUTOTROPHS –organisms that can produce complex organic compounds from simple inorganic molecules. They are the PRODUCERS in a food chain. HETEROTROPHS – organisms that cannot produce their own food, but acquire complex organic molecules by consuming plants or other animals.

7. Photosynthesis LIGHT form the Sun CARBON DIOXIDE from the air WATER from the soil

8. Photosynthesis LIGHT form the Sun GLUCOSE for biomass and energy CARBON DIOXIDE from the air OXYGEN released to the atmosphere WATER from the soil

9. Photosynthesis LIGHT ENERGY CHEMICAL ENERGY

10. Photosynthesis Light Carbon dioxide + water Glucose + oxygen Chlorophyll

11. Photosynthesis Light 6CO2 + 6H2O C6H12O6 + 6O2 Chlorophyll

12. Photosynthesis Light 6CO2 + 6H2O C6H12O6 + 6O2 Chlorophyll Some of the glucose produced is used in respiration by the plant itself, but most of it is converted into insoluble STARCH for storage in stems, roots and leaves.

13. Factors affecting photosynthesis

14. Factors affecting photosynthesis • Temperature • CO2 concentration • Light intensity

15. Factors affecting photosynthesis Temperature Rate of photosynthesis Temperature

16. Factors affecting photosynthesis Temperature As temperature rises, so does the rate of P/S. Here temperature is limiting the rate. Rate of photosynthesis Temperature

17. Factors affecting photosynthesis Temperature Rate of photosynthesis As temperature approaches 45oC, enzymes start to denature and rate of P/S falls to zero Temperature

18. Factors affecting photosynthesis Carbon dioxide concentration As CO2 increases, so does the rate of P/S. At this point [CO2] is the limiting factor. Rate of photosynthesis CO2 concentration

19. Factors affecting photosynthesis Carbon dioxide concentration Rate of photosynthesis Increasing [CO2] has no further effect. The limiting factor must now be sunlight or temperature. CO2 concentration

20. Factors affecting photosynthesis Light Intensity As light intensity increases, so does the rate of P/S. At this point light intensity is the limiting factor. Rate of photosynthesis Light intensity

21. Factors affecting photosynthesis Light Intensity Rate of photosynthesis Increasing light intensity has no further effect. The limiting factor must now be [CO2] or temperature. Light intensity

22. Plant mineral requirements

23. Plant mineral requirements • For healthy growth plants also need certain minerals

24. Plant mineral requirements • For healthy growth plants also need certain minerals • Farmers use fertilisers to add minerals to soil.

25. Plant mineral requirements • For healthy growth plants also need certain minerals • Farmers use fertilisers to add minerals to soil. • Natural fertiliser = dead plants and animals and organic waste.

26. Plant mineral requirements • For healthy growth plants also need certain minerals • Farmers use fertilisers to add minerals to soil. • Natural fertiliser = dead plants and animals and organic waste. • Artificial (manufactured fertiliser) = made in factories from chemicals.

27. Plant mineral requirements

28. Plant mineral requirements Fastgro fertiliser NPK Elements- Nitrogen, Phosphorus, Potassium 20:50:30 Ratio of the elements in the fertiliser

29. Leaf adaptations

30. Leaf adaptations

31. Leaf adaptations Broad Thin Flat Internal air spaces

32. Leaf adaptations Broad Thin Flat Internal air spaces Large surface area

33. Leaf adaptations

34. Leaf adaptations Stomata (stoma) on the undersurface of leaves that allow CO2 to diffuse in and O2 to diffuse out. Water is also lost through the stomata by transpiration.

35. Leaf adaptations Cross section through a leaf

36. Leaf adaptations Cross section through a leaf Waxy cuticle – stops too much water from just evaporating away from the leaf.

37. Leaf adaptations Cross section through a leaf Waxy cuticle – stops too much water from just evaporating away from the leaf. Plants in hot, dry or windy conditions have a thicker wax layer.

38. Leaf adaptations Cross section through a leaf Palisade layer– most of the chloroplasts are found here, containing chlorophyll, the pigment needed for photosynthesis

39. Leaf adaptations Cross section through a leaf Spongy mesophyll layer – less chloroplasts here. Note the large number of air spaces.

40. Leaf adaptations Cross section through a leaf Lower epidermis – note the presence here of stomata (tiny pores surrounded by guard cells).

41. Photosynthesis experiments Light source

42. Photosynthesis experiments Bubbles of oxygen gas being produced Light source Variable: distance of the light source (= intensity) away from the pond weed.

43. Photosynthesis experiments Testing leaves for starch

44. Photosynthesis experiments Testing leaves for starch Variegated leaves

45. Photosynthesis experiments Testing leaves for starch Chlorophyll No chlorophyll

46. Photosynthesis experiments Testing leaves for starch

47. Photosynthesis experiments Testing leaves for starch

48. Photosynthesis experiments Testing leaves for starch

49. Photosynthesis experiments Testing leaves for starch

50. Photosynthesis experiments Testing leaves for starch Positive starch result where the chlorophyll has been extracted (the green parts) Negative starch result in variegated (white) part of leaf where chlorophyll is absent.