Question

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

Answer 1

In genetics, ploidy refers to the number of chromosomes found in a cell's nucleus. The chromosomes are found in pairs in normal somatic (body) cells called diploid condition. During meiosis, the cell creates gametes, or germ cells, with half the amount of chromosomes as normal or somatic cells called haploid. The diploid state is reestablished when two germ cells fuse to form a zygote.

Complete answer:
To solve this question one should at first know a few generalizations about ploidy.
In organisms who have chromosomes in their cells in pairs are called diploid (2n) and their germ cells are produced by the process of meiosis which is a reductional division and the total number chromosomes in the germ cells are reduced to exactly the half and are therefore haploid (n).
Fusion of haploid germ cells produces diploid zygotes. All organisms who have a diplontic life cycle follow this rule and so do plants follow this rule.
Since, it is given in the question that the male gametes of tobacco plants have twenty four chromosomes so the female gametes will also have twenty four chromosomes.
Moreover, the gametes have a haploid state as discussed above. So, twenty four chromosomes is the half of the total number of chromosomes present in the somatic cells of tobacco plants.

Therefore, the zygotes of the tobacco plants will have a diploid state i.e. having forty eight chromosomes as the diploid condition of the zygote is replaced by the fusion of haploid gametes.

Note:
Chromosomes are thread-like structures found within the nucleus of both animal and plant cells. Protein and a single molecule of deoxyribonucleic acid make up each chromosome (DNA). DNA is passed along from parents to children and includes the particular instructions that distinguish each living organism. In the great majority of cell divisions, chromosomes are an important element of the process that guarantees DNA is correctly copied and disseminated.