Cell Cycle and Cell Division — Page 3 | NEET Biology

Q21

Identify the meiotic stage in which the homologous chromosomes separate while the sister chromatids remain associated at their centromeres?

A Metaphase I

B Metaphase II

C Anaphase I

D Anaphase II

Correct Answer

Option C

Solution

(c) In anaphase I, the sister chromatids remain attached at their centromeres and move together toward the poles.

Q22

During gamete formation, the enzyme recombinase participates during

A Metaphase - I

B Anaphase - II

C Prophase - I

D Prophase - II

Correct Answer

Option C

Solution

(c) Recombinase enzyme catalyzes exchange of homologous regions between paired maternal and paternal chromosomes in prophase-I.

Q23

During meiosis I, the chromosomes start pairing at

A Leptotene

B Zygotene

C Pachytene

D Diplotene

Correct Answer

Option B

Solution

(b) During zygotene, chromosomes start pairing together by a process called synapsis.

Q24

Select the correct option: Synapsis, Synthesis of RNA and protein, Action of enzyme recombinase, Centromeres do not separate but chromatids move towards opposite poles

A (ii) (iii) (v) (iv)

B (i) (ii) (v) (iv)

C (ii) (iii) (iv) (v)

D (ii) (i) (iii) (iv)

Correct Answer

Option A

Solution

(a) Pachytene-Crossing over by recombinase; Zygotene-Synapsis; G2 phase-Synthesis of RNA and protein; Anaphase I-Centromeres do not separate.

Q25

In meiosis crossing over is initiated at

A Pachytene

B Leptotene

C Zygotene

D Diplotene

Correct Answer

Option A

Solution

(a) Crossing over occurs in the Pachytene stage of Prophase I of meiosis.

Q26

After meiosis I, the resultant daughter cells have

A four times the amount of DNA in comparison to haploid gamete.

B same amount of DNA as in the parent cell in S phase.

C twice the amount of DNA in comparison to haploid gamete.

D same amount of DNA in comparison to haploid gamete.

Correct Answer

Option C

Solution

(c) After meiosis I the daughter cell will have 2C amount of DNA (twice the haploid gamete amount of 1C).

Q27

Crossing over takes place between which chromatids and in which stage of the cell cycle?

A Non-sister chromatids of non-homologous chromosomes at Pachytene stage of prophase I.

B Non-sister chromatids of non-homologous chromosomes at Zygotene stage of prophase I.

C Non-sister chromatids of homologous chromosomes at Pachytene stage of prophase I.

D Non-sister chromatids of homologous chromosomes at Zygotene stage of prophase I.

Correct Answer

Option C

Solution

(c) Crossing over is the exchange of gene which takes place between non-sister chromatids of homologous chromosomes at pachytene stage.

Q28

Best stage to observe shape, size and number of chromosomes is

A interphase

B metaphase

C prophase

D telophase

Correct Answer

Option B

Solution

(b) During metaphase, centromeres lie on the equatorial plate making it the best time to count and study chromosomes.

Q29

During cell division in apical meristem the nuclear membrane disintegrates at

A metaphase

B anaphase

C telophase

D cytokinesis

Correct Answer

Option C

Solution

(c) Nuclear membrane disintegrates at the end of prophase/beginning of metaphase, reforms at telophase.

Q30

How many mitotic divisions are needed for a single cell to make 128 cells?

A 7

B 14

C 28

D 64

Correct Answer

Option A

Solution

(a) 2^7 = 128, so 7 mitotic divisions are needed.