Question

Pick up the correct statements
(a) Synapses of homologous chromosome take place during prophase I of meiosis
(b) Division of centromeres takes place during anaphase-I of meiosis
(c) Spindle fibers disappear completely in telophase of mitosis
(d) Nucleoli reappear at telophase-I of meiosis

Answer 1

Hint: Chromosomes on the equatorial place move to the corners while the sister chromatids remain associated with the centromeres in anaphase-I of meiosis-I.Individual chromosomes disappear at the final stage of mitosis. Synapsis can be seen in the zygotene phase and nucleoli reappear at the final stage of meiosis-I.

Complete step by step answer:
There are four stages of mitosis namely prophase, metaphase, anaphase, and telophase. Meiosis is divided into two types meiosis-I and meiosis-II. Meiosis-I have four stages: Meiosis-I: prophase-I, metaphase-I, anaphase-I, and telophase-I. Meiosis-II has four phases: prophase-II, metaphase-II, anaphase-II, and telophase-II. Telophase is the final stage of mitosis where complete disappearance of spindle fibers and no individual chromosomes are seen. Prophase-I for meiosis-I is further subdivided into five phases: Leptotene, zygotene, pachytene, diplotene, and diakinesis. Synapses of homologous chromosomes take place in the zygotene stage. sister chromatids remain associated at centromeres and homologous chromosomes separate in anaphase-I.

Additional information:
- As a result of mitosis, two daughter cells are produced at the end. The two daughter cells contain equal numbers of chromosomes same as in parent cells, so it is also called an equational division. it occurs in both haploid and diploid cells
- Four daughter cells are produced at the end of meiosis and each daughter cell has half the number of chromosomes present in the parent cell. so, meiosis is called reduction division. It occurs only in diploid cells.
- A typical eukaryotic cell present in the human body divides approximately once in 24hours.
- interphase and mitotic phase are the two phases in cell division.
- Interphase lasts more than 95% of the duration in the cell cycle.
So, the correct answer is 'A, C, D only'.

Note:
- After the parental chromosomes have replicated to produce two sister chromatids which are identical, meiosis-I is initiated. This occurs in the S phase.
- Meiosis increases the genetic variability from one generation to the next generation in a population.
- In meiosis two cycles occur i.e. meiosis-I and meiosis-II but only one cycle of DNA replication occurs.
- One of the important uses of mitosis is cell repair.
- Some of the cells in the body are constantly replaced by mitosis.