Cell Cycle and Cell Division — Page 6 | NEET Biology

Q51

Meiotic division of the secondary oocyte is completed

A At the time of copulation

B After zygote formation

C At the time of fusion of a sperm with an ovum

D Prior to ovulation

Correct Answer

Option C

Solution

(c) Meiotic division of secondary oocyte is completed after the entry of sperm.

Q52

During the metaphase stage of mitosis spindle fibres attach to chromosomes at

A Centromere

B Kinetochore

C Both centromere and kinetochore

D Centromere, kinetochore and areas adjoining centromere

Correct Answer

Option B

Solution

(b) Kinetochores serve as the sites of attachment of spindle fibres to the chromosomes.

Q53

If APC (Anaphase Promoting Complex) is defective in a human cell, which of the following is expected to occur?

A Chromosomes will be fragmented

B Chromosomes will not segregate

C Recombination of chromosome arms will occur

D Chromosomes will not condense

Correct Answer

Option B

Solution

(b) A defective APC will cause chromosomes to fail to segregate during anaphase.

Q54

Best material for the study of mitosis in laboratory is

A anther

B root tip

C leaf tip

D ovary

Correct Answer

Option B

Solution

(b) Root tip cells are used to study mitosis. Anther cells are used to study meiosis.

Q55

Colchicine is employed to diploidize a haploid cell as it

A inhibits mitosis

B inhibits formation of mitotic spindle

C allows replication of DNA twice in one cell cycle

D inhibits formation of centromere

Correct Answer

Option B

Solution

(b) Colchicine is a mitotic poison which inhibits the formation of spindle fibres.

Q56

Match the following with respect to meiosis events

A & (iv) & (iii) & (ii) & (i) \

B & (i) & (ii) & (iv) & (iii) \

C & (ii) & (iv) & (iii) & (i) \

D & (iii) & (iv) & (i) & (ii) array

Correct Answer

Option A

Solution

(a) Zygotene - Synapsis; Pachytene - Crossing over; Diplotene - Chiasmata formation; Diakinesis - Terminalisation.

Q57

Select the correct option with respect to mitosis.

A Chromatids separate but remain in the centre of the cell in anaphase.

B Chromatids start moving towards opposite poles in telophase.

C Golgi complex and endoplasmic reticulum are still visible at the end of prophase.

D Chromosomes move to the spindle equator and get aligned along equatorial plate in metaphase

Correct Answer

Option D

Solution

(d) In mitosis, chromosomes move to the equator and get aligned along equatorial plate in metaphase.

Q58

Number of chromatids at metaphase is

A two in mitosis and two in meiosis

B two in meiosis and one in mitosis

C two in mitosis and four in meiosis

D one in mitosis and two in meiosis

Correct Answer

Option A

Solution

(a) In both mitotic and meiotic metaphase, the number of chromatids per chromosome is two.

Q59

Choose the correct option for events of meiosis in correct sequence:

A B A C D

B A B C D

C A B D C

D D C B A

Correct Answer

Option A

Solution

(a) Correct sequence: Synapsis, Crossing over, Terminalisation of chiasmata, Disappearance of nucleolus.

Q60

A stage of mitosis shown in diagram: chromosomes move to spindle equator made up of two sister chromatids

A Late prophase - chromosomes align at spindle equator

B Metaphase - spindle fibres attached to kinetochores, centromeres remain intact

C Metaphase - chromosomes move to spindle equator; chromosomes made up of two sister chromatids

D Anaphase - centromeres split and chromatids separate

Correct Answer

Option C

Solution

(c) Metaphase chromosome is made up of two sister chromatids. Chromosomes are moved to spindle equator.