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: 

2.15 understand the processes of diffusion, osmosis and active transport by which substances move into and out of cells 

2.16 understand how factors affect the rate of movement of substances into and out of cells, including the effects of surface area to volume ratio, distance, temperature and concentration gradient 

2.17 practical: investigate diffusion and osmosis using living and non-living systems