iGCSE Biology Section 2 lesson 3

1. iGCSE Biology Section 2 lesson 3

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. Types of nutrition 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.

6. Biological molecules Our diet needs to contain sufficient and balanced quantities of carbohydrates, proteins and lipids.

7. Biological molecules carbohydrates

8. Biological molecules carbohydrates

9. Biological molecules carbohydrates

10. Biological molecules Fats Fats also contain C, H and O, but relatively less O. Fats occur in both plant and animal foods. Fats – solid at room temperatures. Oils - liquid at room temperatures.

11. Biological molecules Fats Fats also contain C, H and O, but relatively less O. Fats occur in both plant and animal foods. Fats – solid at room temperatures. Oils - liquid at room temperatures. Fats also give us energy. They also provide insulation in humans and other mammals, and are energy stores.

12. Biological molecules Proteins Proteins contain C, H and O, and also some nitrogen (N) and a little suplhur (S). Proteins are found in milk, eggs, meat and fish.

13. Biological molecules Proteins Proteins contain C, H and O, and also some nitrogen (N) and a little suplhur (S). Proteins are found in milk, eggs, meat and fish. Proteins are needed for growth and body-building (muscles and skin), and they are also used to make enzymes.

14. Components of our diet Minerals: contain certain elements essential for the proper functioning of our bodies.

15. Components of our diet Minerals: contain certain elements essential for the proper functioning of our bodies.

16. Rickets

17. Components of our diet Minerals: contain certain elements essential for the proper functioning of our bodies.

18. Anaemia

19. Components of our diet Vitamins: a collection of organic substances needed in small quantities in the body. Their overall function is to help control the chemical reactions taking place in the body.

20. Components of our diet Vitamins: a collection of organic substances needed in small quantities in the body. Their overall function is to help control the chemical reactions taking place in the body.

21. Components of our diet Vitamins: a collection of organic substances needed in small quantities in the body. Their overall function is to help control the chemical reactions taking place in the body.

22. Scurvy

23. Components of our diet Vitamins: a collection of organic substances needed in small quantities in the body. Their overall function is to help control the chemical reactions taking place in the body.

24. Components of our diet Fibre is necessary for a healthy balanced diet, but the body can’t absorb it. It helps our digestive system to process food and absorb nutrients. It helps your bowel to pass food by making stools soft and bulky. It helps prevent constipation. Fibre is found in foods such as brown rice, oats, wholegrain breads and cereals.

25. Components of our diet Water makes up more than two-thirds of the weight of the human body. It serves as a lubricant, helps regulate body temperature, prevents and relieves constipation. Without enough water we can become dehydrated.

26. The human digestive system (also known as the alimentary canal) From mouth to anus

27. The human digestive system

28. The human digestive system In digestion, large insoluble molecules are broken down into smaller soluble particles that can be absorbed into the bloodstream.

29. The human digestive system Mouth – mechanical chewing of the food. Salivary glands produce the enzyme amylase which begins breaking down polysaccharides into simpler sugars.

30. The human digestive system Oesophagus (also known as the gullet). Passes food down from the mouth to the stomach by a process known as peristalsis.

31. Peristalsis Rings of muscle around the oesophagus effectively ‘squeeze’ food towards the stomach, as you would with toothpaste in a tube.

32. The human digestive system Stomach – more mechanical digestion happens here. The stomach produces the enzyme protease, and also hydrochloric acid which kills bacteria, and this acid also provides the ideal conditions for protease.

33. The human digestive system Pancreas – produces many enzymes, including amylase, protease and lipase.

34. The human digestive system Small intestine – can be over six metres long. Digested food is absorbed here into the blood stream. The surface area of the small intestine is greatly increased by the presence of small, finger-like projections called villi (villus).

35. Villi

36. The human digestive system Large intestine – as the fibre and other undigested material passes along the large intestine, water is absorbed from it, so it becomes more solid. This solid matter then passes on to the rectum where it is stored as faeces.

37. The human digestive system The Liver – produces a substance known as bile, which is stored in the gall bladder before it is released into the small intestine. Bile has 2 functions:

38. The human digestive system The Liver – produces a substance known as bile, which is stored in the gall bladder before it is released into the small intestine. Bile has 2 functions: 1. It neutralises the acid from the stomach, producing more alkaline conditions.

39. The human digestive system The Liver – produces a substance known as bile, which is stored in the gall bladder before it is released into the small intestine. Bile has 2 functions: 2. It emulsifies fats – i.e. it breaks large drops of fat into small droplets to increase their surface area, so enzymes can work faster.

40. Pause time!

41. definitions

48. Biological molecules Simple sugars Starch / glycogen

49. Biological molecules Fatty acids, glycerol Fats, oils (lipids)

50. Biological molecules Amino acids Proteins