Mitosis and Meiosis Practice Questions
20 free Mitosis and Meiosis practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which event is unique to prophase I of meiosis and does not occur in mitosis?
- A Chromosome condensation into visible structures
- B Formation of the bipolar spindle apparatus
- C Synapsis of homologous chromosomes
- D Disappearance of the nuclear membrane
Correct answer: Synapsis of homologous chromosomes
Synapsis is the pairing of homologous chromosomes, which occurs only during prophase I of meiosis. This pairing allows for genetic recombination and is absent in mitosis.
The main biological significance of meiosis is to:
- A Double the chromosome number carried in gametes
- B Produce genetically identical diploid daughter cells
- C Keep chromosome number constant across generations
- D Enable rapid growth of somatic body tissue
Correct answer: Keep chromosome number constant across generations
Meiosis halves the chromosome number in gametes. Fertilization then restores the diploid number, maintaining chromosome constancy across generations.
Which stage of mitosis involves separation of sister chromatids?
- A Prophase
- B Metaphase
- C Anaphase
- D Telophase
Correct answer: Anaphase
During anaphase, sister chromatids separate and move toward opposite poles. This ensures equal distribution of genetic material.
Crossing over between homologous chromosomes occurs during:
- A Leptotene, when chromosomes first condense
- B Zygotene, when homologs begin pairing
- C Pachytene
- D Diplotene, when chiasmata appear
Correct answer: Pachytene
Crossing over occurs during the pachytene stage of prophase I. It involves exchange of genetic material between non-sister chromatids.
Which of the following cells is produced directly by meiosis?
- A Neuron
- B Muscle cell
- C Sperm cell
- D Liver cell
Correct answer: Sperm cell
Meiosis produces haploid gametes such as sperm cells. Somatic cells like neurons and muscle cells are formed by mitosis.
Which regulatory protein complex controls progression through mitosis?
- A Cyclin A with CDK2, active in S phase
- B Cyclin B–CDK1
- C Cyclin D with CDK4, active in G1
- D Cyclin E with CDK2, at G1/S
Correct answer: Cyclin B–CDK1
Cyclin B–CDK1 complex, also known as MPF, triggers entry into mitosis. Its activation initiates key mitotic events.
Independent assortment of chromosomes occurs during:
- A Metaphase I
- B Anaphase I
- C Metaphase II
- D Anaphase II
Correct answer: Metaphase I
Independent assortment occurs at metaphase I when homologous chromosome pairs align randomly at the equatorial plate. This increases genetic variation.
How many daughter cells are produced after completion of meiosis?
- A Two diploid cells identical to parent
- B Two haploid cells after one division
- C Four diploid cells with full chromosome sets
- D Four haploid cells
Correct answer: Four haploid cells
Meiosis consists of two successive divisions resulting in four haploid daughter cells. Each cell has half the chromosome number of the parent cell.
Which structure attaches chromosomes to spindle fibers?
- A Centromere
- B Telomere, the chromosome end cap
- C Nucleolus, site of ribosome assembly
- D Chiasma, a crossing-over point
Correct answer: Centromere
Spindle fibers attach to chromosomes at the centromere via the kinetochore. This attachment is essential for chromosome movement.
Which checkpoint ensures all chromosomes are properly attached to spindle fibers before separation?
- A G1 checkpoint, before DNA replication
- B G2 checkpoint, before mitotic entry
- C Spindle assembly checkpoint
- D Restriction checkpoint in late G1
Correct answer: Spindle assembly checkpoint
The spindle assembly checkpoint prevents anaphase onset until all chromosomes are correctly attached. This avoids chromosome missegregation.
Meiosis II is best compared to mitosis because both involve:
- A Pairing of homologous chromosomes
- B Reduction of chromosome number
- C Separation of sister chromatids
- D Crossing over events
Correct answer: Separation of sister chromatids
Both meiosis II and mitosis involve separation of sister chromatids. However, meiosis II occurs in haploid cells.
Which protein complex triggers the transition from metaphase to anaphase?
- A Cohesin, holding sister chromatids together
- B Separase, the cohesin-cleaving protease
- C Anaphase-promoting complex
- D Condensin, driving chromosome compaction
Correct answer: Anaphase-promoting complex
The anaphase-promoting complex initiates degradation of securin. This allows separase to cleave cohesin and separate chromatids.
Failure of chromosome separation during meiosis is known as:
- A Synapsis of paired homologous chromosomes
- B Crossing over between non-sister chromatids
- C Nondisjunction
- D Polyploidy from whole-genome duplication
Correct answer: Nondisjunction
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly. It results in abnormal chromosome numbers.
Which phase of mitosis is characterized by reformation of the nuclear envelope?
- A Prophase, when chromosomes condense
- B Metaphase, when chromosomes align centrally
- C Anaphase, when chromatids move apart
- D Telophase
Correct answer: Telophase
During telophase, nuclear membranes re-form around each set of chromosomes. Chromosomes also begin to decondense.
Chiasmata are visible during which stage of meiosis?
- A Leptotene, the earliest prophase I stage
- B Zygotene, when homologs begin synapsis
- C Pachytene, when crossing over occurs
- D Diplotene
Correct answer: Diplotene
Chiasmata become visible during diplotene when homologous chromosomes begin to separate. They represent sites of crossing over.
Which division results in reduction of chromosome number?
- A Mitosis
- B Meiosis I
- C Meiosis II
- D Cytokinesis
Correct answer: Meiosis I
Meiosis I is the reduction division where homologous chromosomes separate. This halves the chromosome number.
Which molecule inhibits CDK activity to regulate cell division?
- A Cyclin, the CDK-activating partner
- B Tubulin, the spindle building block
- C CDK inhibitor proteins
- D Histone, the DNA-packaging protein
Correct answer: CDK inhibitor proteins
CDK inhibitor proteins bind to cyclin-CDK complexes and suppress their activity. This helps control proper timing of cell division.
In which phase do homologous chromosomes move to opposite poles?
- A Anaphase I
- B Anaphase II
- C Metaphase I
- D Metaphase II
Correct answer: Anaphase I
During anaphase I, homologous chromosomes separate and migrate to opposite poles. Sister chromatids remain together at this stage.
Which structure is responsible for cytoplasmic division in animal cells?
- A Cell plate, used in plant cells
- B Cleavage furrow
- C Spindle fiber pulling chromosomes apart
- D Centrosome organizing the spindle poles
Correct answer: Cleavage furrow
Cytokinesis in animal cells occurs through formation of a cleavage furrow. This furrow deepens to divide the cytoplasm.
Which feature distinguishes meiosis from mitosis most clearly?
- A DNA replication before division begins
- B Spindle formation during cell division
- C Genetic variation in daughter cells
- D Chromosome condensation into visible units
Correct answer: Genetic variation in daughter cells
Meiosis produces genetically diverse daughter cells due to crossing over and independent assortment. Mitosis produces genetically identical cells.