7. Human nutrition

7.1 Diet

Core 

1.  Describe what is meant by a balanced diet 

2. State the principal dietary sources and describe the importance of: 

(a) carbohydrates 

(b) fats and oils 

(c) proteins 

(d) vitamins, limited to C and D 

(e) mineral ions, limited to calcium and iron 

(f) fibre (roughage) 

(g) water 

3. State the causes of scurvy and rickets 

7.2 Alimentary canal

Core 

1.  Identify in diagrams and images the main organs of the digestive system, limited to: 

(a) alimentary canal: mouth, oesophagus, stomach, small intestine (duodenum and ileum) and large intestine (colon, rectum, anus) 

(b) associated organs: salivary glands, pancreas, liver and gall bladder 

2.  Describe the functions of the organs of the digestive system listed in 7.2.1, in relation to: 

(a) ingestion – the taking of substances, e.g. food and drink, into the body 

(b) digestion – the breakdown of food 

(c) absorption – the movement of nutrients from the intestines into the blood 

(d) assimilation – uptake and use of nutrients by cells 

(e) egestion – the removal of undigested food from the body as faeces 

7.3 Physical digestion

Core 

1. Describe physical digestion as the breakdown of food into smaller pieces without chemical change to the food molecules 

2. State that physical digestion increases the surface area of food for the action of enzymes in chemical digestion 

3. Identify in diagrams and images the types of human teeth: incisors, canines, premolars and molars 

4. Describe the structure of human teeth, limited to: enamel, dentine, pulp, nerves, blood vessels and cement, and understand that teeth are embedded in bone and the gums 

5. Describe the functions of the types of human teeth in physical digestion of food 

6. Describe the function of the stomach in physical digestion 

Supplement 

7. Outline the role of bile in emulsifying fats and oils to increase the surface area for chemical digestion 

7.4 Chemical digestion

Core

1. Describe chemical digestion as the break down of large insoluble molecules into small soluble molecules 

2. State the role of chemical digestion in producing small soluble molecules that can be absorbed 

3. Describe the functions of enzymes as follows: 

(a) amylase breaks down starch to simple reducing sugars 

(b) proteases break down protein to amino acids 

(c) lipase breaks down fats and oils to fatty acids and glycerol 

4. State where, in the digestive system, amylase, protease and lipase are secreted and where they act 

5. Describe the functions of hydrochloric acid in gastric juice, limited to killing harmful microorganisms in food and providing an acidic pH for optimum enzyme activity 

Supplement 

6. Describe the digestion of starch in the digestive system: 

(a) amylase breaks down starch to maltose 

(b) maltase breaks down maltose to glucose on the membranes of the epithelium lining the small intestine 

7. Describe the digestion of protein by proteases in the digestive system: 

(a) pepsin breaks down protein in the acidic conditions of the stomach 

(b) trypsin breaks down protein in the alkaline conditions of the small intestine 

8. Explain that bile is an alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action 

7.5 Absorption

Core 

1. State that the small intestine is the region where nutrients are absorbed 

2. State that most water is absorbed from the small intestine but that some is also absorbed from the colon 

Supplement 

3. Explain the significance of villi and microvilli in increasing the internal surface area of the small intestine 

4. Describe the structure of a villus 

5. Describe the roles of capillaries and lacteals in villi