Topic: Cell Cycle and Cell Division (Test 5)



Topic: Cell Cycle and Cell Division
Q.1
Plants show mitotic divisions in -------------
A. Somatic cells
B. Diploid cells
C. haploid cells and diploid cells.
D. Haploid cells
Answer : Option C
Explaination / Solution:

The plants can show mitotic divisions in both haploid and diploid cells due to alternation of generations in life cycle.

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Q.2
How many chromosomes are present in each cell of onion root tip?
A. 16 chromosomes
B. 4 chromosomes
C. 2 chromosomes
D. 3 chromosomes
Answer : Option A
Explaination / Solution:

Onion root tip cells have 16 chromosomes in each cell, same as the number of chromosomes in somatic cells.

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Q.3
S phase marks
A. It carries out normal metabolism
B. Chromosome condensation
C. Cytoplasmic growth
D. DNA replication and chromosome duplication.
Answer : Option D
Explaination / Solution:

S phase marks the phase of DNA replication and chromosome duplication. In this phase increase in the amount of DNA takes place. No synthesis of proteins or RNA takes place.

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Q.4
Plant Cytokinesis differ from animals Cytokinesis in having
A. None of these
B. Cell plate
C. Midbody
D. Microfilament
Answer : Option B
Explaination / Solution:

In plants, cytokinesis or division of cytoplasm occurs due to cell plate formed out of deposition of materials along the equatorial region of cell but in animals cytokinesis occurs due to formation of cleavage furrow in the middle cell membrane.

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Q.5
Dinoflagellates possess condensed chromosomes even in interphase, their nucleus is called
A. Cytokaryone
B. Mesokaryon
C. None of these
D. Polykaryone
Answer : Option B
Explaination / Solution:

Dinoflagellates are unicellular protists. They possess condensed chromosomes even during interphase. Their nucleus is called as mesokaryon.

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Q.6
During zygotene stage chromosomes start pairing together and the process is called as
A. Recombination
B. Synapsis
C. Fertilisation
D. Crossing over
Answer : Option B
Explaination / Solution:

During zygotene stage, the homologous chromosomes start pairing together and this process of association is called synapsis. The paired homologous chromosomes are called bivalents.

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Q.7
Chromosome appeared beaded during
A. Leptotene
B. Diakinesis
C. Panchytene
D. Diplotene
Answer : Option A
Explaination / Solution:

Chromosome appeared beaded during leptotene stage of prophase of meiosis I due to the distinct appearance of nucleosomes. Chromatin materials start condensing after that stage.

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Q.8
Small disc like structures that occur in the centromere are
A. Kinetochore
B. Nucleolus
C. Centriole
D. Microtubules
Answer : Option A
Explaination / Solution:

Small disc-shaped structures at the surface of the centromeres are called kinetochores. These structures serve as the sites of attachment of spindle fibres (formed by the spindle fibres) to the chromosomes.

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Q.9
Diplotene stage can lasts for months or years. Dinoflagellates possess condensed chromosomes even in interphase, their nucleus is called
A. Polykaryon
B. Mesokaryon
C. Cytokaryon
D. None of these
Answer : Option B
Explaination / Solution:

In oocytes of some vertebrates, diplotene can last for months or years.Such nucleus showing arrested diplotene stage is called mesokaryotic nucleus.

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Q.10
Cell growth results in disturbing the ratio between
A. Cytoplasm-chromosome ratio
B. Nucleo-cytoplasmic ratio
C. Cytoplasm-spindle fibre ratio
D. Nucleus - chromosome ratio
Answer : Option B
Explaination / Solution:

Cell growth results in disturbing the ratio between the nucleus and the cytoplasm. It therefore becomes essential for the cell to divide to restore the nucleo-cytoplasmic ratio. Cell becomes stable when N/C ratio is 1.

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