Theory question 108
Microorganisms and Health(For candidates in Nigeria only)
(a)(i) What is immunity? (ii) Explain two ways by which a person becomes immune to yellow fever.
(iii) Name four diseases for which babies are immunised.
(b) What is translocation?
(c) State: (i) three differences; (ii) three similarities between the transport systems in flowering plants and mammals.
Show the model answer
(a)(i) Immunity is the ability of the body to resist infection by a disease-causing organism, through antibodies and white blood cells.
(ii) Natural (active) immunity: surviving an attack of yellow fever, the body makes antibodies and memory cells. Artificial (active) immunity: vaccination with yellow fever vaccine (weakened virus) makes the body produce antibodies. (Also passive: antibodies passed from mother to baby.)
(iii) Any four: tuberculosis (BCG); polio; measles; diphtheria; whooping cough (pertussis); tetanus; hepatitis B; yellow fever.
(b) Translocation is the movement of manufactured food (sugars, amino acids) through the phloem from the leaves to other parts of the plant.
(c)(i) Differences: mammals have a heart/pump, plants have none; mammals have blood in vessels (arteries, veins, capillaries), plants have xylem and phloem; mammals have a circulatory (closed loop) system, plants do not circulate; mammal blood carries respiratory gases, plants exchange gases by diffusion; plants carry water in dead xylem, mammals' vessels are living.
(ii) Similarities: both use tubes/vessels; both carry dissolved food; both carry water and mineral salts; both transport hormones; both carry waste products; both use a liquid medium.
Give differences as matching pairs (plant vs mammal).