Question

(a) In a tobacco plant, the male gametes have 24 chromosomes. The number of chromosomes in the female gametes is also 24. What is the number of chromosomes in the zygote produced? How is the chromosome number in the zygote re-established?

OR

(b) Draw a diagram of the longitudinal section of a flower and label: Sepal, Petal, Ovary, and Stigma.

Accepted Answer

48. **(a)** - The zygote receives 24 chromosomes from the male gamete ($n=24$) and 24 from the female gamete ($n=24$). Thus, the zygote has $24 + 24 = 48$ chromosomes ($2n=48$). - The chromosome number is re-established because gametes are formed by **meiosis** (reduction division), which halves the chromosome number from $2n$ to $n$. Fusion of haploid gametes during fertilization restores the original diploid number ($2n$).

Chromosome Number in Gametes and Zygote

Explanation

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