An organism has two pair of chromosomes | Class 11 Biology Chapter Cell cycle and Cell Division, Cell cycle and Cell Division NCERT Solutions

Question:

An organism has two pair of chromosomes (i.e., chromosome number = 4). Diagrammatically represent the chromosomal arrangement during different phases of meiosis-II.

Answer:

In the Meiosis II, the two chromatids of each chromosome separate from each other and goes to separate daughter cells. With the result, the number of chromosomes remains the same as produced by meiosis- I. Meiosis –II is known as homotypic division. The four stage of this division are-

  1. PROPHASE- II: It is very short. It occurs simultaneously in both the nuclei formed by meiosis- I. centrioles, already duplicated, move apart in pairs. Each pair develops astral rays round it to form an ester. Spindle is laid down between the 2 pairs of centrioles. The chromosomes, each comprising two chromatids, become visible in the nucleus. They are set free in the cytoplasm by breaking of the nuclear envelope. Nucleoli disappear.
  2. METAPHASE- II: The chromosomes take up positions at the equator of the spindle, forming a single metaphase plate. The chromatids of each chromosome are joined at their kinetochores by spindle fibres extending from the opposite poles of the spindle as in mitosis.
  3. ANAPHASE- II: The two chromatids of each chromosome start moving away from each other. Finally, they reach the poles of the spindle. Here, they are called the chromosomes. Each pole has haploid number of chromosomes and haploid amount of chromosomes and haploid amount of DNA. This amount is one- fourth of the DNA present in the original cell that started meiosis.
  4. TELOPHASE- II: The group of chromosomes at each pole of the spindle gets closed by a nuclear envelope. Nucleoli are laid down. Astral rays and spindle are lost.

telophase


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Welcome to the NCERT Solutions for Class 11 Biology - Chapter . This page offers a step-by-step solution to the specific question from Excercise 0 , Question 6: An organism has two pair of chromosomes (i.e., chromosome number = 4). Diagrammatically represe....