Theory question 101
Transport in Animals(a) Write a short note on the importance of the presence of an effective transport system in mammals
(b) State eight functions of blood in mammals
(c) List four materials transported in the bodies of flowering plants
Show the model answer
(a) Mammals are large and complex, so their surface area to volume ratio is small and diffusion alone is too slow.
Materials are taken in or made in one part (oxygen in the lungs, digested food in the gut, hormones in glands) but needed in all cells.
Wastes made in cells must be carried to the kidneys, lungs and skin for removal.
So a transport system (blood, heart, vessels and lymph) is needed to move materials quickly round the body.
(b) Any eight: carries digested food from the intestine to cells; carries oxygen from lungs to tissues; carries carbon(IV) oxide to the lungs; carries urea and other wastes to the kidneys; carries hormones to target organs; distributes heat and keeps body temperature steady; white cells engulf germs (phagocytosis); antibodies give immunity; clotting stops bleeding and keeps germs out; carries water and mineral salts.
(c) Any four: water; mineral salts (e.g. nitrates, phosphates); manufactured food (sugars, amino acids); hormones/auxins; oxygen; carbon(IV) oxide; latex and other secretions; waste products.
Link (a) to surface area to volume ratio.