Theory question 101
Cell Structure and Organisation(a) Explain briefly how the structure of each of the following cells relate to their functions: (i) sperm cell; (ii) palisade cell. (b) Make a drawing 8 cm – 10 cm long of the front view of the female reproductive system in humans and label fully. (c) State two differences between reproduction in mammals and in amphibians. (d) State two methods of birth control in humans.
Show the model answer
(a)(i) Sperm cell: long tail (flagellum) lets it swim to the ovum; acrosome in the head holds enzymes that digest a way into the egg; head has a nucleus with half the chromosomes (haploid) to fuse with the egg nucleus; middle piece packed with mitochondria supplies energy for swimming; small and streamlined.
(ii) Palisade cell: many chloroplasts to trap light; long, column-shaped and packed close together just under the upper epidermis, at right angles to the surface, so many cells receive light; thin cell wall lets light and gases pass; chloroplasts can move towards the light; large vacuole holds water.
(b) Front view drawing, 8–10 cm, with title and labels: ovaries, oviducts (Fallopian tubes) with funnels/fimbriae, uterus (with its wall/endometrium), cervix, vagina, (vulva). Symmetrical, clear lines, ruled label lines.
(c) Any two: mammals have internal fertilisation / most amphibians have external fertilisation (in water); mammal embryo develops inside the uterus with a placenta / amphibian eggs develop outside in water; mammals produce few eggs / amphibians produce many eggs; mammals give birth to live young / amphibians lay eggs; mammals show much parental care and feed young on milk / amphibians show little or none; amphibians have a larval (tadpole) stage and metamorphosis / mammals do not.
(d) Any two: condom; diaphragm/cap; contraceptive pill or injection; IUD (loop); spermicides; rhythm (safe period) method; withdrawal; abstinence; vasectomy or tubal ligation.
Link every structural feature to its function with 'so that' or 'for'.