Meiosis I — NEET Biology MCQs with Solutions
Free NEET Biology Meiosis I MCQs with step-by-step solutions (90 questions). Part of Cell Cycle and Cell Division. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Meiosis I · easy · theory
Pairing of homologous chromosomes (synapsis) to form bivalents occurs during:
A. Prophase II
B. Prophase I (zygotene) ✓ Correct
C. Anaphase I
D. Metaphase I
Solution: Homologous chromosomes pair (synapsis) during zygotene of prophase I, forming bivalents/tetrads.
Q2 — Meiosis I · easy · theory
Crossing over — exchange of segments between non-sister chromatids — takes place during the ______ substage of prophase I:
A. Diplotene
B. Pachytene ✓ Correct
C. Leptotene
D. Diakinesis
Solution: Crossing over (recombination) occurs at pachytene, mediated by the recombination nodules on the synaptonemal complex.
Q3 — Meiosis I · medium · theory
The X-shaped points where crossing over has occurred, visible during diplotene, are called:
A. Bivalents
B. Chiasmata ✓ Correct
C. Kinetochores
D. Centromeres
Solution: Chiasmata are the sites of crossover, holding homologues together until anaphase I.
Q4 — Meiosis I · medium · theory
The reduction in chromosome number from diploid to haploid occurs in meiosis I because:
A. Sister chromatids separate
B. Cells fuse
C. DNA replicates again
D. Homologous chromosomes (not sister chromatids) separate ✓ Correct
Solution: Anaphase I separates homologous chromosomes to opposite poles — hence meiosis I is the reductional division.
Q5 — Meiosis I · hard · theory
The correct sequence of prophase I substages is:
A. Pachytene → Diplotene → Zygotene
B. Leptotene → Zygotene → Pachytene → Diplotene → Diakinesis ✓ Correct
C. Zygotene → Leptotene → Pachytene
D. Diakinesis → Leptotene → Zygotene
Solution: Prophase I: leptotene (condensation) → zygotene (synapsis) → pachytene (crossing over) → diplotene (chiasmata) → diakinesis (terminalisation).
Q6 — Meiosis I · hard · theory
In a cell with 2n = 8, the number of bivalents (tetrads) formed during metaphase I is:
A. 4 ✓ Correct
B. 16
C. 2
D. 8
Solution: Homologues pair up, so the number of bivalents = n = 4 (each bivalent has 2 homologues, 4 chromatids).
Q7 — Meiosis I · easy · numerical
Meiosis I is described as a reductional division because at its completion:
A. The two daughter cells receive identical sets of homologous chromosomes
B. The sister chromatids of each chromosome are separated equally
C. The chromosome number is reduced from diploid to haploid as homologous chromosomes are separated ✓ Correct
D. The DNA content doubles while the chromosome number stays the same
Solution: In meiosis I homologous chromosomes (not sister chromatids) separate, halving the chromosome number from 2n to n; hence it is reductional.
Q8 — Meiosis I · easy · numerical
During which substage of prophase I does the synaptonemal complex form fully as homologous chromosomes complete their pairing?
A. Diakinesis
B. Zygotene ✓ Correct
C. Diplotene
D. Leptotene
Solution: Synapsis (pairing of homologues) occurs in zygotene, accompanied by the formation of the synaptonemal complex between the paired chromosomes.
Q9 — Meiosis I · easy · numerical
A pair of synapsed homologous chromosomes, each consisting of two sister chromatids, is collectively called a:
A. Kinetochore
B. Chiasma
C. Centromere
D. Bivalent (tetrad) ✓ Correct
Solution: The paired homologous chromosomes form a bivalent, which contains four chromatids and is therefore also called a tetrad.
Q10 — Meiosis I · easy · numerical
The actual exchange of genetic material between non-sister chromatids of homologous chromosomes during crossing over is mediated by enzymes and takes place at structures called:
A. Kinetochores
B. Cleavage furrows
C. Cell plates
D. Recombination nodules ✓ Correct
Solution: Crossing over occurs at recombination nodules on the synaptonemal complex, where recombining enzymes catalyse exchange between non-sister chromatids during pachytene.
Q11 — Meiosis I · medium · numerical
Arrange the following events of meiosis I in their correct temporal sequence:
(i) Chiasmata become clearly visible (ii) Synaptonemal complex forms (iii) Homologous chromosomes move to opposite poles (iv) Chromosomes condense and homologues are unpaired
A. (iv), (ii), (i), (iii) ✓ Correct
B. (iv), (i), (ii), (iii)
C. (ii), (iv), (i), (iii)
D. (i), (ii), (iv), (iii)
Solution: Leptotene condensation with unpaired homologues comes first, then zygotene synapsis (synaptonemal complex), then diplotene chiasmata, and finally anaphase I separation of homologues.
Q12 — Meiosis I · medium · numerical
Which statement correctly distinguishes the behaviour of chromosomes at anaphase I of meiosis from anaphase of mitosis?
A. In both, centromeres split and single chromatids move to the poles
B. In anaphase I whole homologous chromosomes (each with two chromatids) separate, whereas in mitotic anaphase sister chromatids separate ✓ Correct
C. In anaphase I sister chromatids separate, whereas in mitosis whole chromosomes separate
D. In anaphase I the DNA content of each pole doubles, unlike in mitosis
Solution: At anaphase I, centromeres do NOT split; instead entire homologous chromosomes (each still two chromatids) are pulled apart, unlike mitotic anaphase where sister chromatids separate.
Q13 — Meiosis I · medium · numerical
Assertion (A): Diplotene of prophase I can last for months or even years in the oocytes of some organisms.
Reason (R): During diplotene the synaptonemal complex dissolves and the homologues remain held together only at the chiasmata.
A. A is true but R is false
B. Both A and R are true but R is not the correct explanation of A
C. A is false but R is true
D. Both A and R are true and R is the correct explanation of A ✓ Correct
Solution: Diplotene, marked by dissolution of the synaptonemal complex and homologues held at chiasmata, can be extremely prolonged (months to years) in oocytes; both statements are true and R explains A.
Q14 — Meiosis I · medium · numerical
In a cell with 2n = 12 entering meiosis, how many bivalents form and how many chromatids are present in total during metaphase I?
A. 12 bivalents and 24 chromatids
B. 12 bivalents and 12 chromatids
C. 6 bivalents and 12 chromatids
D. 6 bivalents and 24 chromatids ✓ Correct
Solution: With 2n = 12 there are 6 homologous pairs, giving 6 bivalents; since each chromosome has two chromatids after S phase, there are 12 x 2 = 24 chromatids.
Q15 — Meiosis I · medium · numerical
Match each prophase I substage with its characteristic event:
(i) Leptotene (ii) Pachytene (iii) Diplotene (iv) Diakinesis
(p) Chiasmata terminalise and nucleolus disappears (q) Chromosomes appear as thin threads (r) Crossing over is completed (s) Recombined chromosomes begin to separate revealing chiasmata
A. (i)-q, (ii)-r, (iii)-s, (iv)-p ✓ Correct
B. (i)-q, (ii)-s, (iii)-r, (iv)-p
C. (i)-r, (ii)-q, (iii)-p, (iv)-s
D. (i)-s, (ii)-p, (iii)-q, (iv)-r
Solution: Leptotene = thin threads (q); pachytene = crossing over completed (r); diplotene = homologues separate revealing chiasmata (s); diakinesis = terminalisation of chiasmata and disappearance of nucleolus (p).
Q16 — Meiosis I · medium · numerical
The genetic variation contributed by meiosis I arises from two independent processes occurring before the homologues separate. These are:
A. Crossing over during pachytene and independent assortment of homologous pairs at metaphase I ✓ Correct
B. Chromosome condensation at leptotene and nucleolus reappearance at telophase I
C. DNA replication during S phase and centromere splitting at anaphase I
D. Synapsis during zygotene and cytokinesis after telophase I
Solution: Variation in meiosis I comes from crossing over (recombination between homologues) and the random (independent) assortment of maternal and paternal homologues at metaphase I.
Q17 — Meiosis I · medium
Meiosis involves two cycles of
A. Both (1) and (2) ✓ Correct
B. Nuclear divisions
C. DNA replication
D. Cell division
Solution: Meiosis has two sequential cell and nuclear divisions after a single DNA replication.
Q18 — Meiosis I · easy
The longest phase of meiosis is
A. anaphase-I
B. prophase-I ✓ Correct
C. metaphase-II
D. prophase-II
Solution: Prophase-I is the longest and most complex phase, subdivided into five substages.
Q19 — Meiosis I · medium
The compaction of chromosomes occurs during
A. anaphase-I
B. telophase-I
C. leptotene ✓ Correct
D. pachytene
Solution: During leptotene the chromosomes become gradually compacted and visible.
Q20 — Meiosis I · medium
The synaptonemal complex is formed
A. during metaphase
B. during prophase-I of meiosis ✓ Correct
C. during prophase-II
D. during anaphase
Solution: The synaptonemal complex forms during zygotene of prophase-I.
Q21 — Meiosis I · medium
Which one of the following events does not occur during zygotene?
A. Appearance of bivalents
B. Pairing of chromosomes
C. Involvement of recombinase ✓ Correct
D. Formation of synaptonemal complex
Solution: Recombinase acts during pachytene, not zygotene.
Q22 — Meiosis I · easy
When paternal and maternal chromosomes exchange their genetic material with each other in cell division, this event is called
A. dyad forming
B. synapsis
C. bivalent forming
D. crossing over ✓ Correct
Solution: Crossing over is the exchange of genetic material between homologous chromosomes.
Q23 — Meiosis I · medium
Select the incorrectly matched pair.
A. Equational division - Meiosis-II
B. Animal cell - Persistent spindle
C. Crossing over - Non-homologous chromosomes ✓ Correct
D. Reductional division - Meiosis-I
Solution: Crossing over occurs between homologous, not non-homologous, chromosomes.
Q24 — Meiosis I · easy
The enzyme involved in the process of crossing over is
A. recombinase ✓ Correct
B. DNA polymerase
C. crossinase
D. DNA ligase
Solution: Recombinase mediates crossing over during pachytene.
Q25 — Meiosis I · medium
The stage during which separation of the paired homologous chromosomes begins is
A. pachytene
B. zygotene
C. diakinesis
D. diplotene ✓ Correct
Solution: During diplotene the synaptonemal complex dissolves and homologues begin to separate.
Q26 — Meiosis I · medium
Which of the following events occurs during the diplotene stage of the cell cycle?
A. degeneration of chiasmata
B. degeneration of nucleolus
C. Separation of synapsed homologous chromosomes except at the site of cross overs ✓ Correct
D. All of the above
Solution: In diplotene homologues separate except at chiasmata (crossover sites).
Q27 — Meiosis I · easy
The X-shaped structures observed during diplotene are
A. chiasmata ✓ Correct
B. bivalent complex
C. None of these
D. synaptonemal complex
Solution: Chiasmata are the X-shaped crossover sites visible during diplotene.
Q28 — Meiosis I · medium
Diakinesis is marked by
A. terminalisation of chiasmata
B. degeneration of nucleolus
C. All of the above ✓ Correct
D. fully condensed chromosomes
Solution: Diakinesis shows chiasmata terminalisation, nucleolus disappearance and fully condensed chromosomes.
Q29 — Meiosis I · easy
The major event that occurs during anaphase of mitosis which brings about equal distribution of chromosomes is
A. Splitting of chromatids
B. Condensation of chromatin
C. Replication of genetic material
D. Splitting of centromeres ✓ Correct
Solution: Splitting of centromeres in anaphase allows sister chromatids to move to opposite poles.
Q30 — Meiosis I · medium
In which of the following haploid cells also divide by mitosis?
A. In some lower plants
B. All of the above ✓ Correct
C. Male honey bees
D. In some social insects
Solution: Haploid cells divide mitotically in some lower plants and in social insects like male honey bees.