The following sub-topics are covered in this section. 

(a) Level 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) Co-ordination and response

Students should: 

2.7 identify the chemical elements present in carbohydrates, proteins and lipids (fats and oils) 

2.8 describe the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugars, protein from amino acids, and lipid from fatty acids and glycerol 

2.9 practical: investigate food samples for the presence of glucose, starch, protein and fat 

Students should: 

2.10 understand the role of enzymes as biological catalysts in metabolic reactions 

2.11 understand how temperature changes can affect enzyme function, including changes to the shape of active site 

2.12 practical: investigate how enzyme activity can be affected by changes in temperature 

2.13 understand how enzyme function can be affected by changes in pH altering the active site 

2.14B practical: investigate how enzyme activity can be affected by changes in pH