Abhranti.ai
Explore
Start free

Cell Cycle and Cell Division: questions with answers

Class 11 Biology, Chapter 10 (NCERT). 15 questions by concept, 8 with pictures. Open “Show answer” for the answer and why.

How to teach this chapter · Common misconceptions & worked visual for this chapter

Cell-cycle phases, timing and the G0 state

Question 1

A learner writes, ‘Interphase is a resting period with no metabolic activity, and DNA is copied continuously through G1, S and G2.’ Which option corrects both errors?

  1. (a)Interphase is metabolically inactive, and all DNA replication is moved to M phase.
  2. (b)Interphase is metabolically inactive; DNA replication occurs specifically in S.
  3. (c)Interphase is metabolically active; DNA replication occurs specifically in S, while G1 and G2 support growth and preparation.
  4. (d)Interphase is metabolically active; DNA replication occurs continuously in G1, S and G2.
Show answer

(c) Interphase is metabolically active; DNA replication occurs specifically in S, while G1 and G2 support growth and preparation.

The word resting does not mean that interphase is metabolically inactive. Cells grow and prepare during interphase, but DNA replication is confined to S rather than spread across all three parts.

Question 2

An adult animal cell exits G1, does not currently proliferate, remains metabolically active and can be called on to divide when replacement is needed. Which interpretation is correct?

  1. (a)The cell is dead, because a cell that stops proliferating cannot remain metabolically active.
  2. (b)The cell is in G0: it is metabolically active but not proliferating unless required to re-enter division.
  3. (c)The cell is in M phase, because lack of DNA replication means division is already occurring.
  4. (d)The cell is permanently unable to divide again, even if the organism requires replacement.
Show answer

(b) The cell is in G0: it is metabolically active but not proliferating unless required to re-enter division.

This is the quiescent G0 state. G0 cells are inactive with respect to proliferation, not dead or metabolically inactive, and they may re-enter division when required by the organism.

DNA content and chromosome-number accounting

Question 3

An onion-root cell has 16 chromosomes and 4C DNA after S phase. After it completes mitosis, what does each daughter cell contain?

  1. (a)16 chromosomes and 4C DNA
  2. (b)8 chromosomes and 2C DNA
  3. (c)32 chromosomes and 4C DNA
  4. (d)16 chromosomes and 2C DNA
Show answer

(d) 16 chromosomes and 2C DNA

Mitosis distributes the replicated material between two daughter cells. Each daughter retains the parental chromosome number of 16 and returns to the post-M DNA content of 2C; it does not retain the parent's entire 4C amount.

Mitotic chromosome and spindle dynamics

Question 4

In a mitotic cell, chromosomes began becoming compact before they reached the equator. Later, each replicated chromosome was held there by spindle fibres contacting its central region from the two poles. Which inference best fits all the evidence?

Observed chromosome arrangementA replicated chromosome lies at the cell equator and fibres from the two poles contact its central region. The stage is not named. QUESTION DIAGRAM Observed chromosome arrangement Schematic · not to scale Equator Pole Pole
  1. (a)Condensation began in prophase, fibre contact was at kinetochores, and the sister kinetochores were attached to opposite poles.
  2. (b)Condensation began in prophase, fibre contact was at kinetochores, and both sister kinetochores were attached to one pole.
  3. (c)Condensation began only at metaphase, fibre contact was at kinetochores, and the sister kinetochores were attached to opposite poles.
  4. (d)Condensation began in prophase, fibre contact was along chromosome arms, and the sister kinetochores were attached to opposite poles.
Show answer

(a) Condensation began in prophase, fibre contact was at kinetochores, and the sister kinetochores were attached to opposite poles.

The onset of chromosome condensation belongs to prophase, while complete condensation and equatorial alignment characterise metaphase. The stated central contacts are kinetochores in the centromere region, and stable bipolar alignment requires sister kinetochores to connect to opposite poles.

Question 5

An unlabeled top-to-bottom process strip shows centromeres splitting and daughter chromosomes moving centromere-first toward opposite poles, followed by loss of chromosome identity and formation of two nuclear boundaries. Which interpretation is correct?

  1. (a)Homologous chromosomes separate; later they remain condensed while one original nucleus persists.
  2. (b)Homologous chromosomes separate as daughter chromosomes; later they decondense as daughter nuclei re-form.
  3. (c)Sister chromatids separate as daughter chromosomes; later they decondense as daughter nuclei re-form.
  4. (d)Sister chromatids separate as daughter chromosomes; later they remain condensed without daughter nuclei.
Show answer

(c) Sister chromatids separate as daughter chromosomes; later they decondense as daughter nuclei re-form.

Mitotic anaphase begins with centromere splitting, so sister chromatids become daughter chromosomes and move to opposite poles. In telophase, chromosomes decondense and nuclear envelopes and nucleoli re-form; the separated units in mitosis are not homologous chromosomes.

Question 6

An unlabeled cell redraw shows fully condensed replicated chromosomes aligned with the equator running vertically. Which account correctly explains how this state was reached and maintained?

  1. (a)Condensation began in prophase; fibres contact kinetochores at the centromere region; both sister kinetochores face one pole.
  2. (b)Condensation began in prophase; fibres contact kinetochores at the centromere region; sister kinetochores face opposite poles.
  3. (c)Condensation began only at metaphase; fibres contact kinetochores at the centromere region; sister kinetochores face opposite poles.
  4. (d)Condensation began in prophase; fibres contact chromosome arms; sister kinetochores face opposite poles.
Show answer

(b) Condensation began in prophase; fibres contact kinetochores at the centromere region; sister kinetochores face opposite poles.

Chromosome condensation begins in prophase and is complete by metaphase. At metaphase, spindle fibres contact kinetochores in the centromere region, and the two sister kinetochores connect to opposite poles; the orientation of the cell on the page does not alter these relations.

Prophase I pairing and recombination

Question 7

The diagram shows four chromatids, labelled A to D, in one paired unit during zygotene. Which interpretation of the unit is correct?

ABCD
  1. (a)A and B are sisters within one homologue, C and D are sisters within the other, and synapsis associates the two homologues.
  2. (b)Only the two inner chromatids B and C make the complete bivalent; A and D lie outside it.
  3. (c)A, B, C and D are four separate chromosomes that have not been replicated and so have no sister-chromatid grouping.
  4. (d)Synapsis associates A with B and C with D because sister chromatids are the pairing partners.
Show answer

(a) A and B are sisters within one homologue, C and D are sisters within the other, and synapsis associates the two homologues.

A and B are sister chromatids of one replicated chromosome, while C and D are sisters of the homologous replicated chromosome. Synapsis associates the two homologous chromosomes, so the whole bivalent contains all four chromatids.

Question 8

Which comparison correctly distinguishes the chromatids that cross over in pachytene from the structures linking homologues in zygotene and diplotene?

  1. (a)Homologous chromosomes exchange whole sister-chromatid pairs; dissolution of the complex leaves no connection between them.
  2. (b)Non-sister chromatids exchange material; chiasmata are simply the unchanged synaptonemal complex retained through diplotene.
  3. (c)Non-sister chromatids exchange material; the synaptonemal complex accompanies synapsis, and chiasmata remain after it dissolves.
  4. (d)Sister chromatids of one chromosome exchange material; the other two chromatids are not involved in the bivalent.
Show answer

(c) Non-sister chromatids exchange material; the synaptonemal complex accompanies synapsis, and chiasmata remain after it dissolves.

Crossing over occurs between non-sister chromatids of homologous chromosomes at pachytene recombination nodules. The synaptonemal complex accompanies synapsis in zygotene; after it dissolves in diplotene, homologues remain joined at crossover sites called chiasmata.

Cytokinesis and the significance of mitosis

Question 9

An unlabeled redraw of a walled cell shows a central partition extending outward toward both lateral walls. Which account correctly identifies the cytoplasmic process and contrasts it with nuclear division?

  1. (a)It is plant cytokinesis: a cell plate grows inward from the old lateral walls; karyokinesis divides the nucleus.
  2. (b)It is plant cytokinesis: an inward cleavage furrow divides the cytoplasm; karyokinesis divides the nucleus.
  3. (c)It is plant cytokinesis: a central cell plate grows outward; karyokinesis is the distinct division of the nucleus.
  4. (d)It is plant karyokinesis: the cell plate and nuclear division are the same event.
Show answer

(c) It is plant cytokinesis: a central cell plate grows outward; karyokinesis is the distinct division of the nucleus.

The plant cell plate begins in the centre and grows outward until it meets the existing lateral walls. This is cytokinesis, the division of cytoplasm, and it is distinct from karyokinesis, which segregates chromosomes into daughter nuclei; an animal cell instead develops an inward cleavage furrow.

Question 10

A learner claims: ‘A plant cell pinches inward like an animal cell. Its cell plate starts at the old lateral walls and grows toward the centre. Also, every karyokinesis must be followed by cytokinesis.’ Which correction is complete?

  1. (a)Plant cells use an inward furrow like animals; animals use an inward furrow; karyokinesis without cytokinesis can form a syncytium.
  2. (b)Plant cells form a central plate that grows outward; animals use an inward furrow; karyokinesis without cytokinesis can form a syncytium.
  3. (c)Plant cells form a central plate that grows outward; animals use an inward furrow; karyokinesis must always be followed by cytokinesis.
  4. (d)Plant cells form a plate that grows inward from old walls; animals use an inward furrow; karyokinesis without cytokinesis can form a syncytium.
Show answer

(b) Plant cells form a central plate that grows outward; animals use an inward furrow; karyokinesis without cytokinesis can form a syncytium.

A plant cell begins a cell plate at the centre and extends it outward to the lateral walls, whereas an animal cell forms an inward-deepening cleavage furrow. Karyokinesis need not be followed by cytokinesis; when it is not, a multinucleate syncytium can result.

Meiosis I and II segregation and outcomes

Question 11

The unlabelled diagram shows one meiotic cell at a segregation state. Which interpretation is correct?

  1. (a)This is anaphase II: sister chromatids separate, and the chromosome set is not halved a second time.
  2. (b)This is anaphase II, and it halves the chromosome set because it is the second meiotic division.
  3. (c)This is anaphase II: homologous chromosomes separate while sister chromatids remain joined.
  4. (d)This is metaphase I because the separated chromatids are bivalents aligned at the equator.
Show answer

(a) This is anaphase II: sister chromatids separate, and the chromosome set is not halved a second time.

Centromere splitting and separation of sister chromatids identify anaphase II, a mitosis-like division. Homologous chromosomes separated earlier in anaphase I, which is the division that reduced the chromosome set.

Question 12

The unlabelled diagram shows a meiotic segregation state. Which statement correctly interprets the chromosome movement and centromere condition?

  1. (a)Homologous chromosomes are separating; sister chromatids remain joined and their centromeres are intact.
  2. (b)Sister chromatids are separating; the homologous chromosomes remain together at the equator.
  3. (c)Bivalents are still aligned on the equatorial plate and no chromosome has begun poleward movement.
  4. (d)Homologous chromosomes are separating only after each centromere has split into two.
Show answer

(a) Homologous chromosomes are separating; sister chromatids remain joined and their centromeres are intact.

The two homologous chromosomes move toward opposite poles during anaphase I. Each chromosome still consists of two sister chromatids joined at an intact centromere; centromere splitting and sister separation occur in anaphase II.

Question 13

A learner writes, ‘At anaphase I the centromeres split and sister chromatids separate. DNA then replicates during interkinesis before meiosis II.’ Which diagnosis is complete?

  1. (a)Centromeres stay intact, sister chromatids stay joined, and no DNA replication occurs during interkinesis.
  2. (b)Only sister separation is wrong; centromeres split in anaphase I and DNA replicates during interkinesis.
  3. (c)Only the interkinesis claim is wrong; centromeres split and sister chromatids separate in anaphase I.
  4. (d)Only centromere splitting is wrong; sister chromatids separate in anaphase I and DNA replicates during interkinesis.
Show answer

(a) Centromeres stay intact, sister chromatids stay joined, and no DNA replication occurs during interkinesis.

All three claims are wrong. Anaphase I separates homologous chromosomes while sister chromatids remain joined at intact centromeres, and interkinesis contains no DNA replication.

Mitosis–meiosis comparison and biological significance

Question 14

The diagram shows one chromosome-number transition in a sexual life cycle. Which process-and-consequence pair belongs at the question mark?

2nn?
  1. (a)No restoring process is needed; chromosome number should keep halving in successive generations.
  2. (b)Meiosis only controls chromosome number and cannot contribute genetic variability.
  3. (c)Meiosis; it establishes the haploid phase and its recombination contributes variability.
  4. (d)Fertilisation; it reduces a diploid set to a haploid set.
Show answer

(c) Meiosis; it establishes the haploid phase and its recombination contributes variability.

Meiosis reduces the diploid chromosome set to the haploid phase and recombination during meiosis contributes genetic variability. Fertilisation fuses haploid gametes and restores the diploid phase, preventing progressive chromosome-number loss across generations.

Question 15

A learner compares cell divisions as follows. Which option corrects the complete comparison?

DivisionLearner’s account
MitosisOne reductional division; two haploid daughter cells
MeiosisTwo DNA replications; two divisions; two identical diploid daughter cells
  1. (a)Mitosis is reductional; meiosis has one replication, two divisions and four haploid products.
  2. (b)Mitosis is equational; meiosis has one replication, two divisions and four haploid products.
  3. (c)Mitosis is equational; meiosis has one replication, two divisions and two identical diploid products.
  4. (d)Mitosis is equational; meiosis has two replications, two divisions and four haploid products.
Show answer

(b) Mitosis is equational; meiosis has one replication, two divisions and four haploid products.

Mitosis is equational and generally produces two daughters with the parental chromosome number. Meiosis has one replication followed by two divisions and produces four haploid cells rather than two identical diploid daughters.

Feature (diploid starting cell)MitosisMeiosis
DNA replication before divisionOnceOnce
DivisionsOneTwo
Chromosome-set changeEquationalReduction in meiosis I
Usual productsTwo cells, same chromosome numberFour haploid cells

Common misconception in Cell Cycle and Cell Division

Open full misconception guide →

Does DNA replication double the chromosome count immediately?

Wrong

After S phase a cell has twice as many chromosomes.

Why it feels right. The amount of DNA doubles.

Right

A replicated chromosome has two sister chromatids counted together until they separate.

Worked example

The chromosome count stays at four. Each chromosome has two chromatids after DNA replication.
  1. A diploid cell with 4 chromosomes enters S phase.
  2. After replication it has 4 chromosomes and 8 chromatids.