in the diagram shown below which structure would homologous pairs of chromosomes normally be represented

3 only

Explanation:

The diagram in this question showcases the FERTILIZATION process involving the combination of two haploid (n) gametes i.e. sperm and egg, to form a diploid (2n) ZYGOTE. The gametes are termed "haploid" because they have only one set of chromosomes.

This means that the sperm from the male contributes one set of chromosome (n) while the egg from the female also contributes one set of chromosome (n) to form two sets of chromosome (2n) i.e. n + n = 2n, in the ZYGOTE. This means that, according to the image, homologous pairs of chromosomes would normally be represented in the structure 3, which is a ZYGOTE.