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(a) Explain two roles of diffusion in human beings.
(b) What is meant by each of the following terms?
(i) Crenated cell
(ii) Flaccid cell

Answer Text:
a)- Absorption of digested foods such as glucose, amino acids in the ileum into the blood stream.
- Exchange of gases across the alveolus e.g# CO_2 or O_2# diffuse from
capillaries to the blood.
- Excretion of nitrogenous wastes from cells e.g urea from the blood capillaries into elimination sites.
b) i)- It is an animal cell that loses water by osmosis and shrinks when placed in a hypertonic solution to their cytoplasm.
ii)- It is a plant cell that loses water by osmosis, become flabby or shrink when placed in