NCERT MOST IMPORTANT QUESTIONS CLASS – 11 | BIOLOGY IMPORTANT QUESTIONS | CHAPTER -10 | CELL CYCLE AND CELL DIVISION | EDUGROWN |

In This Post we are  providing Chapter-10 CELL CYCLE AND CELL DIVISION NCERT MOST IMPORTANT QUESTIONS for Class 11 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON CELL CYCLE AND CELL DIVISION

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Question 1:

What is the average cell cycle span for a mammalian cell?

ANSWER:

The average cell cycle span for a mammalian cell is approximately 24 hours.

Question 2:

Distinguish cytokinesis from karyokinesis.

ANSWER:

Cytokinesis	Karyokinesis
(i)	Cytokinesis is the biological process involving the division of a cell’s cytoplasm during mitosis or meiosis.	(i)	Karyokinesis is the biological process involving the division of a cell’s nucleus during mitosis or meiosis.
(ii)	Stages such as prophase, metaphase, anaphase, and telophase are not present in cytokinesis.	(ii)	It is divided into four stages –prophase, metaphase, anaphase, and telophase

Question 3:

Describe the events taking place during interphase.

ANSWER:

Interphase involves a series of changes that prepare a cell for division. It is the period during which the cell experiences growth and DNA replication in an orderly manner. Interphase is divided into three phases.

(i) G₁ phase

(ii) S phase

(iii) G₂ phase

G₁ phase – It is the stage during which the cell grows and prepares its DNA for replication. In this phase, the cell is metabolically active.

S phase – It is the stage during which DNA synthesis occurs. In this phase, the amount of DNA (per cell) doubles, but the chromosome number remains the same.

G₂ phase – In this phase, the cell continues to grow and prepares itself for division. The proteins and RNA required for mitosis are synthesised during this stage.

Question 4:

What is G₀ (quiescent phase) of cell cycle?

ANSWER:

G₀ or quiescent phase is the stage wherein cells remain metabolically active, but do not proliferate unless called to do so. Such cells are used for replacing the cells lost during injury.

Question 5:

Why is mitosis called equational division?

ANSWER:

Mitosis is the process of cell division wherein the chromosomes replicate and get equally distributed into two daughter cells. The chromosome number in each daughter cell is equal to that in the parent cell, i.e., diploid. Hence, mitosis is known as equational division.

Question 6:

Name the stage of cell cycle at which one of the following events occur:

(i) Chromosomes are moved to spindle equator

(ii) Centromere splits and chromatids separate

(iii) Pairing between homologous chromosomes takes place

(iv) Crossing over between homologous chromosomes takes place

ANSWER:

(i) Metaphase

(ii) Anaphase

(iii) Zygotene of meiosis I

(iv) Pachytene of meiosis I

Question 7:

Describe the following:

(a) synapsis (b) bivalent (c) chiasmata

Draw a diagram to illustrate your answer.

ANSWER:

(a) Synapsis

The pairing of homologous chromosomes is called synapsis. This occurs during the second stage of prophase I or zygotene.

(b) Bivalent

Bivalent or tetrad is a pair of synapsed homologous chromosomes. They are formed during the zygotene stage of prophase I of meiosis.

(c) Chiasmata

Chiasmata is the site where two non-sister chromatids of homologous chromosomes have crossed over. It represents the site of cross-over. It is formed during the diplotene stage of prophase I of meiosis.

Question 8:

How does cytokinesis in plant cells differ from that in animal cells?

ANSWER:

Cytokinesis in plant cells	Cytokinesis is animal cells
(i)	The division of the cytoplasm takes place by cell plate formation.	(i)	The division of the cytoplasm takes place by cleavage.
(ii)	Cell plate formation starts at the centre of the cell and grows outward, toward the lateral walls.	(ii)	Cleavage starts at the periphery and then moves inward, dividing the cell into two parts.

Question 9:

Find examples where the four daughter cells from meiosis are equal in size and where they are found unequal in size.

ANSWER:

(a) Spermatogenesis or the formation of sperms in human beings occurs by the process of meiosis. It results in the formation of four equal-sized daughter cells.

(b) Oogenesis or the formation of ovum in human beings occurs by the process of meiosis. It results in the formation of four daughter cells which are unequal in size.

Question 10:

Distinguish anaphase of mitosis from anaphase I of meiosis.

ANSWER:

Anaphase of mitosis	Anaphase I of meiosis
Anaphase is the stage during which the centromere splits and the chromatids separate. The chromosomes move apart, toward the opposite poles. These chromosomes are genetically identical.	During anaphase I, the homologous chromosomes separate, while the chromatids remain attached at their centromeres.Hence, in anaphase I, the chromosomes of each bivalent pair separate, while the sister chromatids remain together.