Distinguish between unisexual and bisexual flowers giving one example of each.
Draw a neat diagram showing fertilisation in a flower and label:
a] Pollen tube
b] Male germ cell
c] Female germ cell, on it.
OR
Draw the diagram showing the germination of pollen on stigma and label the part on which pollination takes place.
Answer the following questions based on diagram given aside.
i] Name the part marked 'P. in the diagram.
ii] How does 'P. reach part 'B'?
iii] State the importance of the part 'C'.
iv] What happens to the part marked 'D' after fertilisation is over?
Mention the role of gamete and zygote in sexually reproducing organisms.

Explanation

Unisexual flowers: The flowers in which either the male or the female reproductive organs are present only, are called unisexual flowers. They are called incomplete flowers. They undergo cross-pollination in order to reproduce.
Example: Papaya, Watermelon, Corn, etc.
Bisexual flowers: The flowers in which both the male and female reproductive organs are present, are known as complete or bisexual flowers. They are capable of selfpollination.
Example: Mustard, rose, lily, hibiscus, etc.

OR
i] Part marked with alphabet W. is Pollen grain.
ii] Part marked with alphabet .B. is stigma. Pollen grain reaches to stigma by external agents such as water, winds, insect and birds.
iii] Part marked with alphabet .C. ispollen tube. After the pollen lands on a suitable stigma, it has to reach the female germcells which are in the ovary. Pollen tube serves this purpose.
iv] Part marked with alphabet .D. is female germ cell. The fusion of male germ cell with the female germ cell resulting in the formation of a single cell known as zygote. After fertilisation, the zygote divides repeatedly to form an embryo which resides inside the seed.
Gametes: sex cells with haploid number of chromosomes.
Zygote: when two gametes of different sex fuses it results in formation of Zygote. It has diploid number of chromosome.