Question

Identify the meiotic stage in which homologous chromosomes separate while the sister chromatids remain associated at their centromeres.
A. Metaphase II
B. Anaphase I
C. Anaphase II
D. Metaphase I

Answer 1

Cell division is defined as a process where mature cells divide to form two equal daughter cells that resemble the parental cell in several characters. The cell that undergoes division is the Mother cell or parent cell and the newly formed are daughter cells. The sequence of events that occur during cell growth and cell division is called the cell cycle.

Complete answer:
Meiosis is a type of cell division that occurs in mature diploid reproductive cells in which the nucleus divides twice but the chromosome replicates only once to form four diploid cells.
It is also termed as a reductional division.
It occurs only once.

It involves the pairing of homologous chromosomes and recombination between them.
The two steps include-
• Meiosis I
• Meiosis II

Meiosis I results in the formation of two haploid cells from one diploid cell. Daughter forms are haploid but contain diploid DNA content.
These undergo further four phases-
• Prophase I- It is the longest phase in meiosis. It contains further five phases-
- Leptotene( Polarisation occurs, bouquet stage)
- Zygotene/Zygonema(Formation of bivalents and synaptonemal complex)
- Pachytene/Pachynema(Crossing over takes place)
- Diplotene/Diplonema(Chiasmata formation)
- Diakinesis(terminalisation of chiasma)

• Metaphase I- Chromosome aligns at equator and bivalents arrange themselves.
• Anaphase I- Separation of homologous chromosomes that starts moving towards opposite poles and tetrad is divided into two daughter dyads.
• Telophase I- Two daughter nuclei are formed but the chromosomes number is half.
• Cytokinesis
Then meiosis II takes place which is similar to Mitosis.

Hence, the correct answer is option (B).

Note: Meiosis II is similar to Mitosis which is an equational division. The mature somatic cells divide but the chromosome number is kept constant. It means the number of chromosomes in a daughter and the number of chromosomes in parents. It involves karyokinesis (Prophase, Metaphase, Anaphase, Telophase) and Cytokinesis(Division of the cell).