Cell Cycle and Cell Division — Class 11 Biology NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 11 Biology chapter "Cell Cycle and Cell Division" — 7 important questions with detailed answers for CBSE board exam preparation.

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TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Cell Cycle and Cell Division" — 7 important questions with detailed answers for CBSE b…

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Jul 23, 2026

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Key Questions Covered:

Define the cell cycle and name its two main phases.
What is mitosis? Describe the phases of mitosis with key events in each.
What is cytokinesis? Describe differences between plant and animal cytokinesis.
What is meiosis? Explain its significance in sexual reproduction.
Describe the stages of meiosis I and meiosis II with key events (5-mark answer).
Explain the significance of crossing over and independent assortment in gener…
+ 1 more questions in the full chapter

Solutions Summary:

Question	Status
Define the cell cycle and name its two main phases.	✓ Solved
What is mitosis? Describe the phases of mitosis with key …	✓ Solved
What is cytokinesis? Describe differences between plant a…	✓ Solved
What is meiosis? Explain its significance in sexual repro…	✓ Solved
Describe the stages of meiosis I and meiosis II with key …	✓ Solved
Explain the significance of crossing over and independent…	✓ Solved

Showing 6 of 7 questions

Q1: Define the cell cycle and name its two main phases.

The cell cycle is the series of events occurring in a cell between one division and the next. It includes the period of growth and DNA replication (interphase) and the period of cell division (M phase). The two main phases are: 1. Interphase: - G1 phase (gap 1): Cell growth, normal metabolic activities, preparation for DNA synthesis. Duration ~20 hours in human somatic cells. - S phase (synthesis): DNA replication; histone proteins synthesized. Chromosome number doubles. Duration ~7 hours. - G2...

Q2: What is mitosis? Describe the phases of mitosis with key events in each.

Mitosis is the process of nuclear division resulting in two daughter nuclei, each with identical chromosome number and genetic content as the parent cell. It maintains genetic continuity. Phases (in order): 1. Prophase: - Chromosomes condense and become visible (each composed of two sister chromatids joined at centromere). - Centrioles move to opposite poles of cell; aster (radiating fibers) forms around each centriole. - Spindle fibers (microtubules) begin to form from centrosomes. - Nuclear e...

Q3: What is cytokinesis? Describe differences between plant and animal cytokinesis.

Cytokinesis is the division of cytoplasm, resulting in two daughter cells after mitosis or meiosis. It occurs during or after telophase. Cytokinesis is distinct from mitosis (nuclear division). Animal cell cytokinesis (furrow cleavage): 1. Cleavage furrow forms at cell equator; deep groove pinches cell in two. 2. Contractile ring of actin and myosin filaments forms beneath cell membrane at equator. 3. Actin and myosin interact, contracting the ring; contracts like a drawstring, pulling cell mem...

Q4: What is meiosis? Explain its significance in sexual reproduction.

Meiosis is a type of cell division producing four genetically distinct haploid (n) cells from one diploid (2n) cell. Occurs in germ cells (reproductive organs) for gamete formation. Significance in sexual reproduction: 1. Reduction division: - Reduces chromosome number from diploid (2n) to haploid (n). - In humans: Diploid cell (46 chromosomes) → four haploid cells (23 chromosomes each). - When gametes fuse during fertilization, diploid number restored in zygote. 2. Generates genetic variation...

Q5: Describe the stages of meiosis I and meiosis II with key events (5-mark answer).

Meiosis consists of two divisions: meiosis I (reduction division) and meiosis II (similar to mitosis). Stages: MEIOSIS I (Reduction division; separates homologous chromosomes): 1. Prophase I (longest and most complex phase): - Homologous chromosomes pair up (synapsis); each pair called bivalent (or tetrad; four chromatids total). - Crossing over (recombination): Homologous chromosomes exchange segments of DNA; creates new combinations of alleles. - Recombination nodules mark sites of crossing ...

Q6: Explain the significance of crossing over and independent assortment in generating genetic variation.

Genetic variation is the differences in alleles (gene versions) between organisms; essential for evolution and population diversity. Two mechanisms in meiosis generate variation: 1. Crossing over (recombination): Mechanism: - Occurs during prophase I of meiosis. - Homologous chromosomes pair (synapsis) as bivalents. - Non-sister chromatids exchange segments of DNA; physically break and rejoin. - Genetic material from one chromatid swaps with corresponding region of homologous chromatid. - Crea...

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