Q5. Which of the following is the first cell of the new generation in all sexually reproducing organisms?

Gametes → Zygote → Embryo
is the sequence of sexual reproduction.
The zygote is formed by the fusion of haploid gametes and then transformed into an embryo by the process called embryogenesis. So, the single celled diploid zygote is the vital link that ensures continuity of species between organisms of one generation and the next.