Question

A female plant has 12 chromosomes in its egg cell and crossed with plant with 24 chromosomes in its microspore mother cells. Number of chromosomes in its zygote will be

48

36

12

24​

Answer 1

Answer:

option 'd' is correct

Explanation:

As egg cell is haploid so chromosome no. will remain same i.e., 12

But microspore mother cells are diploid (chr no. -24).

As you know that MMC (microspore mother cell) undergoes meiotic (reduction) division and forms microspore tetrad (4) which on dehydration develops into pollen grains (haploid). In mature pollen grain (on mitosis) there're 2 cells, larger vegetative cell and floating small generative cell. The generative cell undergoes further mitotic division and forms 2 male gametes (haploid).

then, the no. of chromosome of male gamete will be 12

So, the no. of chromosome in zygote (diploid) will be 24

Answer 2

Answer:

The number of cells in the zygote when a female plant with 12 chromosomes in its egg cell and 24 chromosomes in its microspore mother cells will be 24.

Explanation:

What are the types of cell division?

Cell division is broadly divided into two types:

• Mitosis or equational cell division or somatic cell division
• Meiosis or reductional cell division

Where does meiosis occur and what is its significance?

Meiosis or reductional cell division occurs in the germ cells of sexually reproducing organisms. Meiosis results in the formation of four haploid daughter cells (gametes).

Meiosis is significantly important because:

• It helps to maintain the ploidy level in the organisms. During meiosis, haploid gametes are formed, i.e., gametes have half the number of chromosomes is present in the parent cells.
• During meiosis, crossing over occurs, which results in variations within the offspring, which supports evolution.

(Refer to the image for detailed understanding)

What are microspore mother cells?

These are the male germ that divides meiotically to give rise to four haploid pollen grains.

Conclusion:

Thus, the microspore mother cell containing 24 chromosomes initially, will divide meiotically to give rise to four haploid pollen grains having 12 chromosomes each.

Now, one of the pollen grains will fertilize the ovule and fuse with the haploid egg cell (which contains 12 chromosomes) to form a zygote, which will contain 12 + 12 = 24 chromosomes.

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