At which point in the diagram does fertilisation happen?
A) Point A
B) Point B
C) Point C
D) Point D
▶️ Answer/Explanation
Ans: C
Fertilisation occurs when sperm and egg fuse to form a zygote. The diagram shows:
- Point A: Egg production (oogenesis)
- Point B: Sperm production (spermatogenesis)
- Point C: Fusion of gametes (fertilisation)
- Point D: Embryo development (post-fertilisation)
Since fertilisation specifically refers to the fusion of gametes, Point C is the correct answer. This is the only stage where both haploid gametes combine to form a diploid zygote.
The nuclei of which two structures fuse during fertilisation?
A) two eggs
B) two embryos
C) two gametes
D) two zygotes
▶️ Answer/Explanation
Ans: C
During fertilisation, the nuclei of two gametes (sperm and egg) fuse to form a diploid zygote. This is a fundamental process in sexual reproduction.
Option A is incorrect because two eggs cannot fuse. Option B is incorrect as embryos are multicellular and formed post-fertilisation. Option D is incorrect because zygotes are the product of fertilisation, not the structures that fuse. Thus, the correct answer is C (two gametes).