Question

The cells of the fruit fly contain 3 pairs of autosomal chromosomes and one pair of sex chromosomes. After meiosis II, how many chromosomes will be present in each gamete?
A. 2
B. 4
C. 6
D. 8
E. 16

Answer 1

Hint: In the meiosis cell division, one gamete cell divides and gives rise to four daughter cells. Each of the daughter cells carries half of the chromosome numbers of the organism. For example, in case of human total of 46 chromosomes are present, so in gamete cells only 23 chromosomes will be present.

Step by step answer:The meiosis division takes place during the formation of gametes.
The meiosis division divides into two parts – meiosis I and meiosis II.
In meiosis I, one parent cell divides and forms two daughter cells with half the number of chromosomes present in it. In meiosis II, the two newly formed daughter cells divide and form four gamete cells that have identical numbers of chromosomes. Therefore, one gamete cell divides and gives rise to four daughter cells. According to the question, the fly has 3 pairs of autosomal chromosome and one pair of sex chromosome. Thus, it has a total 4 pairs of chromosomes. Four pairs of chromosomes mean eight chromosomes in total. In meiosis I, each daughter cell will contain half the number of chromosomes – it means 4 chromosomes. Similarly, in meiosis II, the daughter cells will carry 4 chromosomes as there is no change in chromosome number in meiosis two.
Hence option B is correct.

Note: As the chromosome numbers get halved in meiosis division, it is called the reduction division. All types of recombination and crossing over takes place in the meiosis division.