Question

The table below shows the concentration of sodium and iodine ions in pond water and in the cell sap of water lettuce plant.

	Sodium ion concentration	Iodine ion concentration
Pond water	180	0.4
Cell sap	90	500

1. Giving reasons, name the process through which each of the ions is taken up by the plant.
   • Sodium ion. 
   • Iodine ion. 
2. The lettuce plant was then treated with a chemical substance that inhibits the synthesis of ATP. Giving reasons, state which ion uptake was affected by the treatment. 
3. Explain why fresh water fish cannot survive in marine habitat. 

Answer 1

1.    
   • Diffusion; because its uptake occurs according to the concentration gradient.
   • active transport; because its uptake occurs against concentration gradient;
2. Iodine; its uptake depends on energy derived from ATP;
3. This is because the fresh water fish would lose water molecules to the marine habitat since the marine environment is hypertonic