31 Years NEET Previous Year Questions: Cell Cycle And Cell Division - 1


25 Questions MCQ Test Biology 28 Years NEET/AIPMT Question Papers of Class 11 | 31 Years NEET Previous Year Questions: Cell Cycle And Cell Division - 1


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QUESTION: 1

Meiosis I is reductional division. Meiosis II is equational division due to

Solution:

 

In meiosis I, the starting cell is diploid, and it produces 2 haploid daughter cells. Since the number of chromosomes was halved, it is a reductional division. Note that while each of the daughter cells is haploid, each of the chromosomes in the daughter cells consists of 2 sister chromatids joined together.

In meiosis II, the starting cells are haploid, and each one produces 2 haploid daughter cells. Since the number of chromosomes remained the same, it is an equational division.

QUESTION: 2

Segregation of mendelian factor (Aa) occurs during

[1990]

Solution:

Segregation of Mendelian factor (Aaoccurs during Anaphase-I. During Anaphase-I chromosome divides at the point of centromere or kinetochore and thus two sister chromatids are formed, which are called as chromosomes.

QUESTION: 3

Mitotic anaphase differs from metaphase in possessing

[1991]

Solution:

Mitotic anaphase differs from metaphase in possessing same number of chromosomes and half number of chromatids. During anaphase of mitosis, chromosomes divide at the point of centromere or kinetochore and thus two sister chromatids are formed which are called as chromosomes. While during metaphase, chromosomes become maximally distinct due to further contraction and thus size of chromosomes is measured at mitotic metaphase.

QUESTION: 4

In meiosis, the daughter cells differ from parent cell as well as amongst themselves due to

[1991]

Solution:

Due to segregation, independent assortment and crossing over at the time of meiosis, daughter cells exhibit variation.

QUESTION: 5

 When does synapsis occur during meiosis?

Solution:

In meiosis I, synapsis formation occurs in the zygotene stage of prophase-I. It is the second stage of prophase-I. During this stage, the chromosomes start pairing together and this process of association called synapsis. Such paired chromosomes are called homologous chromosomes. This synapsis is accompanied by the formation of synaptonemal complex formed by bivalent or tetrad chromosomes. 

QUESTION: 6

Meiosis II performs

[1993]

Solution:

Meiosis II is homotypic division specially for maintanence of the haploid number, separating the chromatids from each other in a chromosome.

QUESTION: 7

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

[1994]

Solution:

During metaphase, the centomeres of the chromosome lie on the equatorial plate according to their size and spatial arrangement. So it is the best time to count the number and study the morphology of chromosomes.

QUESTION: 8

Meiosis is evolutionary significant because it result in

[1994]

Solution:

Meiosis provides a chance for new combinations of chromosomes mainly by the phenomenon of crossing over and random distribution of homologous chromosomes between daughter cells.

QUESTION: 9

The exchange of genetic material between chromatids of paired homologous chromosomes during first meiotic division is called

[1996]

Solution:

The points of attachment between homologous chromosomes after their separation in diplotene are called  chiasmata. The process of pairing of homologous chromosomes is called synapsis the phenomenon by which DNA isolated from one type of cell, when introduced into another type, is able to bestow some of the properties of the former to the latter is known as transformation.

QUESTION: 10

In cell cycle, DNA replication takes place in

[1996, 2000]

Solution:

G1 phase, also called Gap I phase is characterized by increase in cell size. In the S phase or synthetic phase DNA molecules replicate. G2 is the second growth phase. Gap II where in there is intensive formation of RNAs and  proteins. In the mitotic metaphase, the chromosomes are arranged at the equatorial plate.

QUESTION: 11

Lampbrush chromosomes occur during

[1996]

Solution:

Lampbrush chromosomes are highly elongated bivalent chromosomes of diplotene stage, which are held together by chiasmata and  have a large number of lateral loops for rapid transcription.

QUESTION: 12

Colchicine is employed to diploidize a haploid cell as it

[1996]

Solution:

Colchicine is a mitotic poison which inhibits the appearance of spindle fibres.

QUESTION: 13

Which one of the following structures will not be common to mitotic cells of higher plants?

[1997]

Solution:

Plants cells do not have centrioles. Cell plate appears during cytokinesis in dividing cells. Centromere holds the sister chromatids in a chromosome. Spindle fibres appear during metaphase.

QUESTION: 14

How many mitotic divisions are needed for a single cell to make 128 cells? [1997]

Solution:

Seven mitotic divisions are required to form 128 cells from a single cell. If we start with one cell and it doubles after one round, we have 2 cells. Those 2 cells double to form 4 cells, then those 4 cells double to form 8. The math continues until we reach 128 cells.

QUESTION: 15

During cell division in apical meristem the nuclear membrane appears in

[1997]

Solution:

Metaphase in characterized by the appearance of spindle fibres. Anaphase involves movement of chromatids towards the poles. Cytokinesis marks the division of the cytoplasm of the parent cell into daughter cells.

The nuclear membrane is present at prophase, when the cell moves from prophase it disappers and again it reappears in telophase.

QUESTION: 16

Microtubule is involved in the

[1998]

Solution:

The spindle fibres involved in cell division is made of microtubules

QUESTION: 17

A bacterium divides every 35 minutes. If a culture containing 105 cells per ml is grown for 175 minutes, what will be the cell concentration per ml after 175 minutes?

[1998]

Solution:

QUESTION: 18

During cell division, the spindle fibres attach to the chromosome at a region called

[2000]

Solution:

Kinetochore is the proteinaceous covering of centriole, to which spindle fibers attach.

QUESTION: 19

Best material for the study of mitosis in laboratory is

[2002]

Solution:

Root tip is the part of the plant which grows continuously as it search water and nutrients. Thats why we can use the root tip for the study of mitosis in a laboratory easily.

QUESTION: 20

If a diploid cell is treated with colchicine then it becomes

[2002]

Solution:

Colchicine inhibits spindle formation, due to which chromatids are unable to separate during anaphase which results in doubling of chromosomes. So, if a diploid cell is treated with colchicine, there is doubling of chromosomes and it becomes tetraploid,. Its an alkaloid obtained from Colchicum autumnale.

QUESTION: 21

In the somatic cell cycle

[2004]

Solution:

DNA replication is restricted to S­ phase of interphase.  G2 phase is followed by the mitotic phase which is shorter than the inter phase.  In G2  phase DNA content is double than the amount present in the original cell.

QUESTION: 22

If you are provided with root­tips of onion in your class and are asked to count the chromosomes, which of the following stages can you most conveniently look into?

[2004]

Solution:

Chromosomes are most distinct  in the metaphase stage. In the telophase stage they  regain their  coiled composition. In anaphase the chromatids separate and move towards opposite poles. In prophase stage the chromosomes appear thread like and individual chromatids cannot be seen.

QUESTION: 23

Which one of the following precedes reformation of the nuclear envelope during M phase of the cell cycle

[2004]

Solution:

At telophase stage, nuclear membrane vesicles associate with the surface of individual chromosomes and fuse to reform the nuclear membranes, which partially enclose clusters of chromosomes before coalescing to reform the complete nuclear envelope. During this process the nuclear pores reassemble and   (the dephosphorylated reassociare to form the nuclear lamina.) One of the lamina proteins (lamina - B) remains with the nuclear membrane fragments throughout mitosis and may help nucleate ressembly. After the nucleus reforms, the pores pump in nuclear proteins, the chromosome decondense and RNA synthesis causing the nucleolus to reappear.

QUESTION: 24

At what stage of the cell cycle are histone proteins synthesized in a eukaryotic cell?

[2005]

Solution:

Histone proteins are synthesized during S­phase of cell cycle. S­phase or Synthetic phase.

 Histone proteins are basic proteins and are used in packing of eukaryotic (absent in prokaryotes) DNA. DNA and histones together comprise chromatin, forming bulk of the eukaryotic chromosomes. Histones are of five major kinds 

H1,H2A,H2B,H3

 and 

H4H1

 histones link neighbouring nucleosomes (fundamental packing units of an eukaryotic chromosome), while other are elements of nucleosome structure. During S-phase of cell cycle synthesis of histone proteins take place because at this stage number of chromosomes become double to that of somatic number

QUESTION: 25

Given below is a schematic break­up of the phases / stages of cell cycle:

Which one of the following is the correct indication of the stage/phase in the cell cycle?

[2009] 

Solution:

In schematic break­up of the phases/ stages of cell cycle, D synthetic phase is the correct indicat