(a) (i) Define asexual reproduction. (ii) Name two types of asexual reproduction which occur in animals giving one example in each case. (b) In a tabular fo...

Answer Details

(a)(i) Definition of asexual reproduction

Asexual reproduction is the production of a new individual (offspring) from a single parent without the fusion of gametes (no fertilization) and without any change in the chromosome number. The offspring produced are genetically identical to the parent.

(a)(ii) Two types of asexual reproduction in animals (with one example each)

• Binary fission - the parent divides into two equal daughter cells. Example: Amoeba (or Paramecium).
• Budding - a small outgrowth (bud) develops on the parent and later detaches to form a new individual. Example: Hydra (or Obelia).

(Sporulation in Plasmodium, or parthenogenesis in aphids and honey bees, are also acceptable.)

(b) Four differences between sexual and asexual reproduction

(c) Large, labelled diagram of the human spermatozoon (8 - 10 cm long)

The spermatozoon is divided into three main regions: the head (bearing the acrosome and the haploid nucleus), the middle piece (packed with mitochondria arranged in a spiral around the axial filament), and the long whip-like tail (flagellum) used for swimming.

(d) One function each of three organelles found in the spermatozoon

• Acrosome (cap of the head): contains digestive (lytic) enzymes that dissolve the membranes surrounding the ovum, allowing the sperm to penetrate and fertilize the egg.
• Nucleus (in the head): carries the haploid number of chromosomes (the male genetic material / DNA) that combine with those of the ovum at fertilization.
• Mitochondria (in the middle piece): contain respiratory enzymes and release energy (ATP) that powers the beating of the tail for the sperm's movement.