NEETZoologyHuman Reproduction
During oogenesis, the secondary oocyte is released from the Graafian follicle during ovulation. Which of the following correctly describes the chromosomal configuration of this cell?
Options
- AIt is haploid with 23 chromosomes, each having a single chromatid.
- BIt is haploid with 23 chromosomes, each having two sister chromatids.
- CIt is diploid with 46 chromosomes, each having a single chromatid.
- DIt is diploid with 46 chromosomes, each having two sister chromatids.
Correct answer
B. It is haploid with 23 chromosomes, each having two sister chromatids.
Step-by-step solution
A secondary oocyte is formed after the completion of Meiosis I, which is a reductional division. Therefore, it is a haploid cell containing 23 chromosomes. At the time of ovulation, the secondary oocyte is arrested in Metaphase II of Meiosis II. Because the centromeres have not yet split (which happens during Anaphase II), each of the 23 chromosomes still consists of two sister chromatids. The separation into single chromatids only occurs after fertilization when Meiosis II is completed to form the ovum. Confusing