Cell Cycle and Cell Division
16 solved NEET Biology previous year questions on Cell Cycle and Cell Division, each with the correct answer and a full explanation.
Q1
Which stage of meiotic prophase shows terminalisation of chiasmata as its distinctive feature?
✓ Correct answer: b) Diakinesis
ExplanationDiakinesis is the final stage of meiotic prophase I and is marked by terminalisation of chiasmata.Leptotene is the first stage of meiotic prophase I and in this stage, the chromosomes become gradually visible under the light microscope.Zygotene is the second stage of prophase I and this stage is characterised by synapsis.Pachytene is the third stage of meiotic prophase I and this stage is characterised by the appearance of recombination nodules.
Q2
Mitotic anaphase differs from metaphase in possessing:
✓ Correct answer: d) Same number of chromosomes and half number of chromatids
ExplanationThe correct answer is option D Explaination Mitotic anaphase differs from metaphase primarily in how the chromosomes are arranged and distributed within the cell.Let's break down the options: A. Same number of chromosomes and same number of chromatids - This is incorrect.In anaphase, the sister chromatids of each chromosome separate, so there are still the same number of chromosomes but each chromosome now only has one chromatid.B. Half number of chromosomes and half number of chromatids - This is incorrect.Anaphase doesn't reduce the number of chromosomes; instead, it separates the sister chromatids, so each chromosome retains the same number but with only one chromatid.C. Half number of chromosomes and same number of chromatids - This is incorrect.Anaphase doesn't halve the number of chromosomes; it separates the sister chromatids, so the number of chromosomes remains the same, but each chromosome now only has one chromatid.D. Same number of chromosomes and half number of chromatids - This is correct.In anaphase, the number of chromosomes remains the same as in metaphase, but each chromosome now only has one chromatid instead of two, as they've been separated and are moving toward opposite poles of the cell.So, the correct option is Option D: Same number of chromosomes and half number of chromatids.
Q3
Which statement best explains the evolutionary advantage of meiosis?
✓ Correct answer: b) Genetic recombinations are possible from generation to generation
ExplanationDuring crossing over of meiosis, exchange of genetic material takes place between non- sister chromatids of homologous chromosomes and result in genetic recombination.In every generation, this recombination occurs at the time of gamete formation.
Q4
If you are provided with root-tips of onion in your class and are asked to count the chromosomes, which of the following stages can you most conveniently look into?
✓ Correct answer: a) Metaphase
ExplanationThe correct answer is: A — Metaphase Explanation: During metaphase, chromosomes are highly condensed and aligned at the cell’s equatorial plate, making them easiest to visualize and count under a microscope.In prophase, chromosomes are thin and thread-like.In anaphase, chromatids are separating, and in telophase, chromosomes start decondensing, both making counting difficult.
Q5
During mitosis ER and nucleolus begin to disappear at:
✓ Correct answer: d) Late prophase
ExplanationCells at the end of prophase, when viewed under microscope do not show Golgi complexes, endoplasmic reticulum, nucleolus and the nuclear envelope.
Q6
The complex formed by a pair of synapsed homologous chromosomes is called
✓ Correct answer: a) bivalent
ExplanationA bivalent, also sometimes referred to as a tetrad, is the complex structure formed during prophase I of meiosis when a pair of homologous chromosomes synapse, or physically pair up.This pairing is essential for genetic recombination (crossing over) and the correct segregation of chromosomes during cell division.
Q7
During meiosis I, dissolution of the synaptonemal complex occurs during: [NEET 2020]
✓ Correct answer: b) diplotene
ExplanationDiplotene stage is characterised by the dissolution of the synaptonemal complex, and X-shaped structures called chiasmata.
Q8
Identify the correct statement with regard to phase (Gap 1) of interphase.
✓ Correct answer: b) Cell is metabolically active, grows but does not replicate its DNA
ExplanationDuring phase, the cell is metabolically active and continuously grows but does not replicate its DNA.S or synthesis phase marks the period during which DNA synthesis or replication takes place.Reorganisation of all cell components takes place in M-Phase.
Q9
During meiosis-I, in which stage synapsis takes place? [Re-NEET 2020]
✓ Correct answer: b) Zygotene
ExplanationSynapsis is the process of pairing homologous chromosomes during prophase I of meiosis, and it specifically occurs in the zygotene stage.During this phase, homologous chromosomes come together and align gene by gene to form bivalents (or tetrads).This alignment is facilitated by the formation of a protein structure called the synaptonemal complex, which holds the homologs tightly together.This pairing is essential for genetic recombination and proper segregation of chromosomes.The other stages of prophase I are leptotene (chromosome condensation), pachytene (crossing over), diplotene (chiasmata visible), and diakinesis (terminalization).
Q10
Which of the following stages of meiosis involves division of centromere? [NEET 2021]
✓ Correct answer: b) Anaphase II
ExplanationIn Anaphase II, simultaneous splitting of centromere of each chromosome takes place due to which they move to opposite poles.In Metaphase II, the chromosomes align at the equator and the spindle fibres get attached to the kinetochores of sister chromatids.Telophase II is a stage which marks the end of meiosis where the chromosomes once again get enclosed by a nuclear envelope.Metaphase I is a stage in which bivalent chromosomes align on the equatorial plate.
Q11
Bivalent or tetrad formation is a characteristic feature observed during:
✓ Correct answer: b) synaptonemal complex in zygotene stage.
ExplanationBivalent or tetrad formation is characteristic of the synaptonemal complex in the zygotene stage of meiosis.(NCERT Edition 2025-26 Class 11th Page No. 126)
Q12
Select the incorrect statement with reference to mitosis: [NEET 2022]
✓ Correct answer: c) Spindle fibres attach to centromere of chromosomes
ExplanationThe incorrect statement is option C. During mitosis, spindle fibres do not attach directly to the centromere but to a specialised protein structure called the kinetochore located on the centromere.Other statements are correct: centromere splitting occurs during anaphase, chromosomes align at the equator during metaphase, and decondensation occurs in telophase.
Q13
The appearance of recombination nodules on homologous chromosomes during meiosis characterizes
✓ Correct answer: d) Sites at which crossing over occurs
ExplanationThe pachytene stage of prophase I of meiosis I is characterised by the appearance of recombination nodules.These are the sites at which crossing over occurs between non-sister chromatids of the homologous chromosomes.
Q14
The process of appearance of recombination nodules occurs at which sub stage of prophase I in meiosis? [NEET 2023]
✓ Correct answer: a) Pachytene
ExplanationRecombination nodules appear during Pachytene, marking the site of genetic exchange (crossing over).Zygotene involves synapsis but no crossing over.Diplotene marks the start of chiasmata formation, and Diakinesis involves terminalization.
Q15
Given below are two statements: Statement I : Chromosomes become gradually visible under light microscope during leptotene stage. Statement II : The beginning of diplotene stage is recognized by dissolution of synaptonemal complex. In the light of the above statements, choose the correct answer from the options given below: [NEET 2024]
✓ Correct answer: b) Both Statement I and Statement II are true
ExplanationStatement I (True): During leptotene (the first substage of prophase I of meiosis), chromosomes begin to condense and become visible as thin, thread-like structures under a light microscope.Statement II (True): During diplotene, the synaptonemal complex (formed during zygotene and pachytene for synapsis) starts to dissolve, and homologous chromosomes begin to separate, remaining connected only at chiasmata.
Q16
Spindle fibers attach to kinetochores of chromosomes during [NEET 2024]
✓ Correct answer: c) Metaphase
ExplanationDuring metaphase, spindle fibers attach to the kinetochores of chromosomes, aligning them at the metaphase plate.This ensures proper chromosome segregation before anaphase begins.
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