(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, 8cm t...

(a) How the structure of each cell relates to its function

(i) Sperm cell

• It has a long, whip-like tail (flagellum) which lashes from side to side to propel the cell so that it can swim to reach the egg (ovum).
• Its head bears an acrosome filled with digestive enzymes that break down and penetrate the membrane of the egg at fertilisation.
• The head contains a haploid nucleus which fuses with the nucleus of the ovum during fertilisation to form the zygote.
• The middle piece is packed with mitochondria that release the energy (ATP) needed to power the beating of the tail during swimming.

(ii) Palisade cell

• It has a thin cell wall which allows easy penetration of light and rapid diffusion of gases.
• It contains numerous chloroplasts arranged in the peripheral cytoplasm for maximum absorption of sunlight for photosynthesis.
• It is long and column-shaped and closely packed just below the upper epidermis so that many chloroplasts are exposed to light.
• It has a large central vacuole containing cell sap which pushes the chloroplasts to the edges near the light and stores the products of photosynthesis temporarily.

(b) Drawing of the front (anterior) view of the human female reproductive system

The diagram below shows the front view of the female reproductive system, about 8-10 cm long when drawn, fully labelled.

(c) Two differences between reproduction in mammals and in amphibians

(d) Two methods of birth control in humans

• Use of contraceptive pills (hormonal method).
• Use of condoms (barrier method).