Q.Fill in the blank: ____ haploid cells are formed during meiotic division.
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Meiosis Overview
Think about what happens when a sperm meets an egg. Each one carries half the number of chromosomes of a normal body cell. When they fuse, the full number is restored. If sperm and egg were made by ordinary cell division (mitosis), each would have the full set — and fusion would double it every generation. That would be a disaster.
So nature invented a special division that cuts the chromosome number in half. That is meiosis.
The core idea in one sentence
Meiosis is a two-step division process that converts one diploid cell (2n) into four haploid cells (n), each genetically different from the parent and from each other.
The "two-step" part is crucial. Unlike mitosis, which is a single division, meiosis happens in two consecutive rounds: Meiosis I and Meiosis II.
Why two rounds?
The first round, Meiosis I, is the reductional division. Here, homologous chromosomes (one from each parent) pair up and then separate. The chromosome number drops from diploid to haploid. Each daughter cell after Meiosis I has one copy of each chromosome — but each chromosome still consists of two sister chromatids.
The second round, Meiosis II, is the equational division. It looks very much like mitosis. The sister chromatids finally separate. Each of the two cells from Meiosis I divides again, giving four haploid cells in total.
The key difference between the two rounds: in Meiosis I, homologous chromosomes separate; in Meiosis II, sister chromatids separate.
What happens to the chromosomes?
Start with a diploid cell. For a human, that means 46 chromosomes — 23 pairs. Each pair consists of one chromosome from your mother and one from your father. These are homologous chromosomes.
Before meiosis begins, DNA replication happens once, just like before mitosis. So each chromosome now has two identical sister chromatids. But the chromosome number is still 46 (each chromosome, even with two chromatids, counts as one chromosome).
Meiosis I — the homologous pairs line up together, exchange segments (crossing over), and then get pulled to opposite poles. The cell divides. Now you have two cells, each with 23 chromosomes. But each of those 23 chromosomes still has two chromatids. The number has been halved: from 46 to 23.
Meiosis II — no further DNA replication. The chromosomes line up again, and this time the sister chromatids separate. Each of the two cells divides, giving four cells. Each has 23 chromosomes, and each chromosome is now a single chromatid. …
Meiosis is a reductional division in which one diploid cell undergoes two successive divisions after a single round of DNA replication, so the number of daughter cells produced is fi …
Meiosis produces four haploid daughter cells from one diploid parent cell.
Meiosis involves a single round of DNA replication followed by two successive divisions:
- Meiosis I is the reductional division: homologous chromosomes pair (synapsis), exchange segments (crossing over) and then separate, halving the chromosome number from diploid (2n) to haploid (n) and giving two cells.
- Meiosis II is like mitosis: the sister chromatids of each of those two cells separate, producing a total of four cells. …
- CBSE 2026Set ANNUAL1 markMCQQ.The phase between Meiosis I and Meiosis II is(a) Prophase II(b) Interkinesis(c) Karyokinesis(d) Diplotene
›Reveal solutionSolution
Interkinesis is the short interval, without DNA replication, that separates the two meiotic divisions.
Meiosis involves two successive divisions: Meiosis I (reductional division, halving chromosome number) followed by Meiosis II (equational division, similar to mitosis). Between the end of telophase I and the start of prophase II, cells pass through a brief phase called interkinesis, which is usually short-lived and, critically, does NOT involve replication of DNA (since the chromosome number is already reduced and each chromosome already has two sister chromatids from the pre-meiotic S-phase).
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- CBSE 2026Set ANNUAL1 markQ.What are Meiocytes?
›Reveal solutionSolution
Meiocytes are diploid cells specialised to undergo meiosis, halving the chromosome number to produce haploid products.
In a sexually reproducing organism, not all cells divide by meiosis — only certain designated diploid cells, called meiocytes, are competent to undergo meiosis. During meiosis, a single meiocyte undergoes one round of DNA replication followed by two successive nuclear divisions (meiosis I and meiosis II), producing four haploid (n) daughter cells. In animals, meiocytes give rise to gametes (sperm/egg); in flowering plants, they give rise to spores — for example, pollen mother c …
- CBSE 2023Set ANNUAL1 markQ.Fill in the blank: ____ haploid cells are formed during meiotic division.
›Reveal solutionSolution
Meiosis produces four haploid daughter cells from one diploid parent cell.
Meiosis involves a single round of DNA replication followed by two successive divisions:
- Meiosis I is the reductional division: homologous chromosomes pair (synapsis), exchange segments (crossing over) and then separate, halving the chromosome number from diploid (2n) to haploid (n) and giving two cells.
- Meiosis II is like mitosis: the sister chromatids of each of those two cells separate, producing a total of four cells. …
- CBSE 2022Set TERM11 markMCQQ.A type of cell division which reduces chromosome number to half is(a) Mitosis(b) Meiosis(c) Both(1) and(2)(d) None of these
›Reveal solutionSolution
Only meiosis reduces the chromosome number to half; mitosis maintains it.
Mitosis is an equational division: one diploid (2n) parent cell produces two diploid (2n) daughter cells with the SAME chromosome number as the parent -- used for growth and repair. Meiosis, in contrast, is a reductional division involving two successive divisions (meiosis I and meiosis II) but only ONE round of DNA replication: a diploid (2n) parent cell ultimately produces four haploid (n) daughter cells, each with HALF the chromosome number of the parent. This halving happens specifically at anaphase I, …
- CBSE 2022Set ANNUAL1 markQ.What type of cell division takes place in germ cells?
›Reveal solutionSolution
Meiosis is the type of division that occurs in germ cells to produce gametes.
Somatic (body) cells divide by mitosis, producing two genetically identical diploid daughter cells for growth and repair. Germ cells (in the gonads — testes and ovaries), however, undergo meiosis, a special two-step division (meiosis I and meiosis II) that reduces the chromosome number by half, from diploid (2n) to haploid (n), and also introduces genetic variation through crossing ov …
- CBSE 2022Set ANNUAL1 markMCQQ.Which one is diploid structure?(a) ovaries(b) endosperm(c) zygote(d) All of these
›Reveal solutionSolution
Zygote is diploid (2n); endosperm is triploid → (c).
- The zygote forms by fusion of two haploid gametes → it is diploid (2n).
- In angiosperms the endosperm results from triple fusion (2 polar nuclei + 1 sperm) → triploid (3n), not diploid. …
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