(a)(i) Explain the term courtship behaviour in animals. (ii) How does courtship aid reproduction in animals? (b) Describe the process of fertilization in fl...

Answer Details

(a)(i) Courtship behaviour

Courtship behaviour is a series of special activities or displays carried out by an animal (usually the male) to attract a mate of the same species, and to prepare both partners for mating. It includes displays such as special calls, songs, dances, release of scents (pheromones), colour displays, nest building and offering of food.

(a)(ii) How courtship aids reproduction

• It enables members of the same species to recognise and attract one another, preventing wasteful mating between different species.
• It helps each partner to identify the sex of the other, so that a male attracts a female and not another male.
• It ensures that the female is sexually receptive and ready to mate, so that mating and fertilization succeed.
• It synchronises the release of sperms and eggs, increasing the chance of fertilization.
• It reduces aggression between the sexes, so that mating can take place peacefully.
• It allows the female to select a strong, healthy mate, so that fit offspring are produced.

(b) Fertilization in flowering plants

Fertilization is the fusion of the male gamete with the female gamete to form a zygote. In flowering plants it follows pollination and occurs as follows:

1. After pollination, a pollen grain lands on the sticky stigma and absorbs sugary fluid.
2. The pollen grain germinates and grows a pollen tube which is guided by the tube nucleus down through the style towards the ovary.
3. The pollen tube secretes enzymes that digest the tissues of the style, making a path for its growth.
4. Inside the pollen tube the generative nucleus divides to form two male gametes (male nuclei).
5. The pollen tube enters the ovule through a small pore called the micropyle.
6. The tip of the tube bursts and releases the two male gametes into the embryo sac.
7. Double fertilization then occurs: one male gamete fuses with the egg cell (ovum) to form a diploid zygote, which develops into the embryo; the second male gamete fuses with the two polar nuclei to form a triploid primary endosperm nucleus, which develops into the endosperm (food store).
8. After fertilization the ovule develops into a seed and the ovary develops into a fruit.