Class 11 Biology Important Chapter 10 Cell Cycle and Cell Division

Class 11 Biology Important Chapter 10 Cell Cycle and Cell Division Solutions English Medium As Per AHSEC New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters ASSEB Class 11 Biology Important Solutions and select need one. AHSEC Class 11 Biology Additional Notes English Medium Download PDF. HS 1st Year Biology Important Solutions in English.

Class 11 Biology Important Chapter 10 Cell Cycle and Cell Division

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Cell Cycle and Cell Division

Chapter: 10

IMPORTANT QUESTION AND ANSWER

Very Short and Short Answer Type Question: 

1. Define the cell cycle. Name its two main phases.

Ans: The cell cycle is the sequence of events that a cell undergoes to grow and divide.

It consists of:

(i) Interphase – period of growth and DNA replication.

(ii) M phase – mitotic phase where the cell divides.

2. Name the method by which cytokinesis takes place in plant cell.

Ans. By the formation of cell plate.

3. Name the stage of meiosis in which crossing over occurs.

Ans. Diplotene of prophase I.

4. Define cytokinesis.

Ans. Division of cytoplasm is defined as cytokinesis.

5.  In which phase of cell division the chromosomes are set free in the cytoplasm?

Ans. Prophase stage.

6. What is a kinetochore?

Ans. A part of the chromosome for the attachment of chromosomal fibres.

7. Name the chemical that arrests cell division in cells.

Ans. (i) Colchicine,

(ii) Cyanide.

8. What is G₀ phase? Give one example of a cell in G₀ phase.

Ans: G₀ phase is a resting phase where cells do not divide but remain metabolically active.

Example: Nerve cells (neurons) remain in G₀ permanently.

9. Describe the crossing over and enzyme involved.

Ans: Pachytene of Meiosis I – Each bivalent chromosome is made of tetrad – four chromatids two of each chromosome. Bivalent have recombination nodules site of crossing over between non-sister chromatids of homologous chromosomes. Crossing over is an enzyme mediated process and enzyme is called recombinase.

10. What is the significance of mitosis.

Ans. Significance of Mitosis:

(i)  Mitosis is essential for growth of multicellular organisms.

(ii) It restores the nucleocytoplasmic ratio through division.

(iii) Cell repair and healing is by repeated mitotic divisions of healthy cells.

(iv) Daughter cells have the same number and type of chromosomes as present in parent cell – called equational division.

11. Enlist any four significant aspects of mitosis.

Ans. Four significant Aspects of Mitosis:

(i) Mitosis is divided into 4 stages: (a) Pro-phase, (b) metaphase, (c) anaphase and (d) telophase.

(ii) It is called Equational division since the number of chromosomes remains same in parent and the progeny (daughter cell).

(iii) In prophase, chromosomes condense, nuclear envelope disappears; in metaphase, chromosomes reach equational plate; centromeres divide in anaphase.

(iv) In Telophase, the nucleus and its membrane again reappear.

12. Mention four significance of mitosis. 

Ans. Four Significances of Mitosis:

(i) The number of chromosomes in mitosis cell division remains constant in daughter cells.

(ii) Asexual reproduction occurs by the help of mitosis.

(iii) The size of the cell is controlled by mitosis.

(iv) Growth and development of the zygote is maintained through mitosis.

13. What are chiasmata ? State their significance.

Ans. Chiasmata: These are the points of crossing of two non-sister chromatids during prophase I of meiosis.

Significance of Chiasmata: The genetic constitution of the daughter cells differs from the parent cells due to crossing over. There is a mixture of paternal and maternal gene in each chromosome of daughter cells mostly.