a. Trace the path a male gamete takes to fertilise a female gamete after being released from the penis.
b. State the number of sets of chromosomes present in a zygote.

In tobacco plant, the male gametes have twenty four chromosomes. What is the number of chromosomes in the female gamete? What is the number of chromosomes in the zygote?

The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote. (a) What are chromosomes (i) B (ii) D, and (iii) E ? (b) Out of B, D and E, which two chromosomes are of the same type ? (c) Which chromosome is smaller in size ? (d) What is the general name of chromosomes such as B and E ? (e) Out of the two persons A and C, which one is (i) male, and (ii) female ?

Given below are a few statements related to external fertilisation. Choose the correct statements. (i) The male and female gametes are formed and released simultaneously. (ii) Only a few gametes are released into the medium. (iii) Water is the medium in a majority of organisms exhibiting external fertilisation. (iv) Offspring formed as a result of external fertilisation have better chance of survival than those formed inside an organism.

In humans, what is the ratio of the number of gametes produced from one male primary sex cell to the number of gametes produced from one female primary sex cell?