Question

Which cell is normally produced as a direct result of meiosis?
A. A uterine cell having half the normal species number of chromosomes
B. An egg having the full species number of chromosomes
C. A zygote having the full species number of chromosomes
D. A sperm having half the normal species number of chromosomes

Answer 1

Meiosis is the process in which four cells are formed from a single cell. During meiosis, the ploidy level gets halved. Moreover, the male and female gametes are produced by the meiotic divisions, due to which they are haploid.

Complete step by step answer: Let us look at all the options given to us one by one.
Option A: A uterine cell having half the normal species number of chromosomes - The uterine cells are the somatic cells. Somatic cells are formed by the differentiation of the germinal layers. The divisions are usually mitotic due to which the ploidy level is restored in each division. Due to this reason, the uterine cells are diploid. They have a normal species number of chromosomes.
Option B: An egg having the full species number of chromosomes - The egg cells are the gamete cells. Egg cells are formed by the differentiation of the oogonia. The divisions are usually meiotic due to which the ploidy level is halved in each division. Due to this reason, the egg cells are haploid. They have half the full species number of chromosomes.
Option C: A zygote having the full species number of chromosomes - The zygote is formed through the fusion of male and female gamete. These cells are not formed by divisions. As the fusion of two haploids gametes occurs to form the zygote, hence the ploidy level of the zygote is doubled in each fusion. Due to this reason, the zygote is diploid. They have the full species number of chromosomes.
Option D: A sperm having half the normal species number of chromosomes - The sperm cells are the gamete cells. Sperm cells are formed by the differentiation of spermatogonia. The divisions are usually meiotic due to which the ploidy level is halved in each division. Due to this reason, the sperm cells are haploid. They have half the full species number of chromosomes.
Thus, based on the above information we can conclude that a sperm having half the normal species number of chromosomes is normally produced as a direct result of meiosis.
Hence, the correct answer is option (D).

Note: The eggs and sperms are formed from the oogonium and spermatogonium by mitotic divisions to form primary oocyte and the primary spermatocytes respectively. After this, the primary spermatocytes undergo 2 meiotic divisions and differentiation to form sperms. On the other hand, the primary oocytes undergo 1 meiotic division and differentiation to form the ovum.