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CBSE Questions for Class 11 Medical Biology Cell Cycle And Cell Division Quiz 6 - MCQExams.com
CBSE
Class 11 Medical Biology
Cell Cycle And Cell Division
Quiz 6
A stage of mitosis in which chromosomes get arranged in the form of an equatorial plate in the centre of a dividing cell is called as
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0%
Prophase
0%
Metaphase
0%
Anaphase
0%
Telophase
Explanation
Metaphase is the second stage of mitosis. In this phase, the spindle fibres begin attaching to the condensed chromosomes. The microtubules adjust the chromosomes in such a way that they appear in a line called the metaphase plate in preparation for their segregation. Thus the correct answer is option B.
At which of the following stages of cell division, the separation of chromatids and their movement to opposite poles occur?
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0%
Prophase
0%
Anaphase
0%
Metaphase
0%
Telophase
Explanation
In anaphase, there is a shortening of the spindle microtubules. Each chromosome is pulled along by its centromere the two sister chromatids of each chromosome are pulled apart by the spindle and dragged by their kinetochores toward opposite poles of the cell. Thus the correct answer is option B.
How many divisions must occur in a cell of root tip to form 128 cells?
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128
0%
127
0%
64
0%
8
Explanation
The plant cell divides mitotically to form two cells. For the formation of 128 cells, the plant cell needs to divide 2$$^n$$ times. When the parent cell will divide for the first time to produce 2 cells, this is the first division. Later on, the two cells will divide 2$$^7$$ times for the production of 128 cells. So, the total number of mitotic divisions by one cell in the root tip to form 128 cells will be 8 divisions.
Thus, the correct answer is option D.
During meiosis, crossing over occurs at
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0%
Diplotene
0%
Leptotene
0%
Pachytene
0%
Diakinesis
Explanation
During pachytene the non-sister chromatids exchange the DNA segments and leads to formation of recombination. This process is known as crossing over.
.......... is the longest stage of meiotic division.
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0%
Prophase
0%
Metaphase
0%
Anaphase
0%
Telophase
Explanation
Meiosis is a reductional division which is comprised of meiosis-I and II. In meiosis-I, the prophase-I is the longest phase. The prophase is divided into 5 stages in which the process of recombination takes place which is responsible for genetic variation. The sequence of the stages are Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.
Thus, the correct answer is option A.
If cells in process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested?
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0%
Anaphase
0%
Prophase
0%
Telophase
0%
Metaphase
Explanation
Colchicine inhibits the formation of microtubules by inhibiting tubulin, a protein required for microtubule synthesis. Microtubules in the form of spindle fibers during cell division pull the DNA from the center of the mother cell into the new daughter cells. If microtubules are not formed DNA will not move into new cells. Hence new cell formation will be inhibited in the metaphase stage. Thus the correct answer is option D.
The chronological sequence of stages in prophase of meiosis is
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Leptotene, Pachytene, Zygotene, Diakinesis, Diplotene
0%
Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis
0%
Zygotene, Leptotene, Pachytene, Diakinesis, Diplotene
0%
Diplotene, Diakinesis, Pachytene, Zygotene, Leptotene
Explanation
Meiosis is a reductional division which is comprised of meiosis-I and II. In meiosis-I, the prophase-I is the longest phase. The prophase is divided into 5 stages in which the process of recombination takes place which is responsible for genetic variation. The sequence of the stages are Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.
Thus, the correct answer is option B.
Crossing over occurs between
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Non-sister chromatids of non homologous chromosomes
0%
Non-sister chromatids of homologous chromosomes
0%
Sister chromatids of homologous chromosomes
0%
Sister chromatids of non-homologous chromosomes
Explanation
Correct Answer: B
Explanation:
Crossing over
is the phenomenon of the
exchange of chromatid segments
or
genetic material between
homologous chromosomes
occurring during the
pachytene stage
of meiosis-I.
Each chromosome has its homologue, that is there are
two chromosomes
of
each type
called a
Homologous chromosome, derived from each parent
that is mother and father.
The
two chromatids
of the
same chromosome
are known as
sister chromatid
while
chromatid belonging
to the
different chromosome
of the
homologous pair
is called
non-sister chromatid
.
During the pachytene stage, the
appearance of recombination nodules occurs
, the sites at which
crossing over
takes place
,
between
non-sister chromatids of the homologous chromosomes
.
Crossing over leads to the
recombination of genetic material
on the two chromosomes.
Hence, the correct answer is
non-sister chromatid of homologous chromosomes
.
............ occurs only during meiosis.
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0%
Pairing of homologues
0%
Separation of duplicated strands
0%
Cytokinesis
0%
Disappearance of nucleolus
Explanation
Meiosis generally occurs in the reproductive cell. One chromosome
of each homologous
pair comes from the mother (called as a maternal chromosome
) and one comes from the father (paternal chromosome). Homologous chromosomes
are similar but not identical. Each carries the same genes in the same order, but the alleles for each trait may not be the same.
The pairing of homologous chromosomes is an essential feature of meiosis, acting to promote high levels of recombination and to ensure segregation of homologs.
So, the correct answer is option A.
In which phase of mitosis the chromatids of chromosomes separate from each other?
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Anaphase
0%
Telophase
0%
Metaphase
0%
Prophase
Explanation
Anaphase is the fourth phase of mitosis. It is characterised by following key events: i) centromere splits and chromatids get separated ii) Chromatids move to opposite poles
So, the correct answer is '
Anaphase'
Separation of homologous chromosomes is termed
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0%
Cross over
0%
Disjunction
0%
Dispersion
0%
Bivalent formation
Explanation
Disjunction is a
normal process by which the two homologs of each chromosome
in a meiotic cell
separate and move to different gametes
.
This occurs in Anaphase I of meiosis. The separated chromosomes or univalents are also called dyads because each of them consists of two chromatids which remain joined with each other at the centromere.
Therefore, the correct answer is option B.
Disjunction is
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0%
Incompatibility of genes
0%
Separation of homologous chromosomes at anaphase
0%
Modification of gene action by a nonallelic gene
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Chromosome aberration involving deletion
Explanation
Anaphase I is a step in meiosis I. In this phase two chromosomes of each bivalent separate and move towards the opposite poles due to spindle action. In anaphase II of meiosis II, the sister chromatids are pulled apart.
This separation of homologous chromosomes and sister chromatids in anaphase I and II respectively is called disjunction.
Thus the correct answer is option B.
When does pairing of homologous chromosomes occur in meiosis?
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Leptotene
0%
Zygotene
0%
Pachytene
0%
Diplotene
Explanation
In zygotene, the homologous chromosomes come to lie side by side and get attached laterally due to the development of nucleoprotein between them. Pairing is such that the genes of the same character present on the two chromosomes come to lie exactly opposite. This pairing of homologous chromosomes is called as synapsis or syndesis.
The separation of daughter chromosomes takes place at
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0%
Prophase
0%
Metaphase
0%
Anaphase
0%
Telophase
Explanation
In anaphase, there is a shortening of the spindle microtubules. Each daughter chromosome is pulled along by its centromere. The two sister chromatids of each chromosome are pulled apart by the spindle and dragged by their kinetochores toward opposite poles of the cell. Thus the correct answer is option C.
The number of chromatids in a chromosome at metaphase is
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One in mitosis and two in meiosis
0%
Two in mitosis and one in meiosis
0%
Two each in mitosis and meiosis
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Two in mitosis and four in meiosis
Explanation
The DNA replicates in the S-phase of interphase in both the types of cell division. The replicated DNA is arranged as sister chromatids on the same chromosomes. In the metaphase in both meiosis as well as mitosis, there are two chromatids in the chromosome.
Thus, the correct answer is option C.
Meiosis has evolutionary significance because it results in
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0%
Eggs and sperms
0%
Recombinations
0%
Four daughter cells
0%
Genetically similar daughter cells
Explanation
Crossing over is the process which occurs in meiosis I. The genetic material gets exchanged between the non-sister chromatids of the two homologous chromosomes which are obtained as one from the mother (maternal) and one from the father (paternal). The genetic exchange is responsible for the variation in the genetic composition of the offspring due to recombination. The recombination helps in bringing variation and contributes towards evolution.
Thus, the correct answer is option B.
Meiosis involves
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One nuclear division and one chromosome division
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One nuclear division and two chromosome divisions
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Two nuclear divisions and one chromosome division
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Two nuclear divisions and two chromosome divisions
Explanation
Meiosis is the cell division which results in the formation of four haploid cells from the diploid parent cell. There are two phases, meiosis I and meiosis II. The nuclear division occurs twice. There is a breaking of the chromosomes only in the anaphase II of meiosis II. In meiosis I, there is a separation of chromosomes towards opposite pole without breaking of the centromere.
Thus, the correct answer is option C.
Which phase of cell cycle is involved in chaisma formation?
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Leptotene
0%
Diplotene
0%
Pachytene
0%
Zygotene
Explanation
A chiasma is a region where two homologous non-sister chromatids meet and exchange genetic material during chromosomal crossover in meiosis.
The crossing over of genetic material occurs during the pachytene stage.
Thus the correct answer is option C.
The crossing over results in
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Linkage between genes
0%
Recombination of alleles
0%
Dominance of alleles
0%
Segregation of alleles
Explanation
Chromosomal crossover is the exchange of genetic material between 2 homologous chromosomes that results in recombinant chromosomes during sexual reproduction. The effect is to shuffle the alleles on parental chromosomes so that the gametes carry combinations of genes different from either parent.
So, the correct option is 'Recombination of alleles'.
A plant cell has $$12$$ chromosomes at the end of mitosis. How many chromosomes would it have in the $$G_2$$ phase of its next cell cycle?
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$$24$$
0%
$$12$$
0%
$$8$$
0%
$$6$$
Explanation
Mitosis is the equational division in which the parent cell divides to produce identical two daughter cells. The plant cell have 12 chromosomes after mitosis. The number of chromosomes in the G$$_2$$ phase will be same as 12 chromosomes with 24 chromatids due to the replication of the DNA in the S-phase.
Thus, the correct answer is option B.
During meiosis, homologous chromosomes pair with one another.
This is known as
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Spiralisation
0%
Synapsis
0%
Crossing over
0%
Chiasmata
Explanation
Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis.
So, B is the correct option.
In meiosis, the daughter cell receive
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Maternal chromosomes only
0%
Paternal chromosomes only
0%
A mixture of maternal and paternal chromosomes
0%
None of the above
Explanation
Meiosis is the cell division which results in the formation of four haploid cells from the diploid parent cell. The homologous chromosomes contain the paternal and maternal chromosome. There is genetic recombination between the two chromosomes which results in the exchange of the genes. So, the daughter cell or the gamete contains combination or mixture of maternal and paternal chromosomes.
Thus, the correct answer is option C.
The repulsion of homologous chromosomes begins during
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0%
Diplotene
0%
Diakinesis
0%
Leptotene
0%
Zygotene
Explanation
Diplotene a stage of meiotic prophase in which the paired homologous chromosomes begin to separate due to repulsion and chiasmata become visible. Thus the correct answer is option A.
Which among the following is the longest phase of meiosis?
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Prophase I
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Anaphase I
0%
Prophase II
0%
Metaphase II
Explanation
A-
Prophase I of mieosis I is longer and more complex than mitosis. It is divided into 5 substages based on chromosomal behaviour i.e Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.
The best cell division stage to observe the shape, size and
number
of chromosome is
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Metaphase
0%
Interphase
0%
Prophase
0%
Telophase
Explanation
The best cell division stage to observe the shape, size and number of chromosomes is the metaphase. The chromosomes appear shortest and thickest during this phase and are arranged at the equator and form an apparent plate called as equatorial or metaphase plate thus readily visible. Therefore, this phase is often chosen for karyotyping and for chromosome analysis.
So, the correct answer is option A.
The number of chromosome in a daughter cell obtained after meiosis is __
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2n
0%
2n+1
0%
n
0%
3n
Explanation
Meiosis takes place in 2 steps. During first step the number of chromosomes in the diploid cell reduces to half and then in second step the 2 daughter cells get divided to 4 haploid cells.
The colchicine prevents the mitosis of cells at which of the following stage?
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Anaphase
0%
Metaphase
0%
Prophase
0%
Interphase
Explanation
If a cell is treated with drugs such as Colchicine, vincistrine, the assembly of the microtubules is inhibited, while the dis-assembly continues leading to continues disorganization of microtubules. Colchicine is an alkaloid. It can be extracted from corms of plant
Colchicum autumnale
and
C. luteum
. Colchicines prevent spindle formation during mitotic metaphase. Thus, it prevents the separation of chromosomes during anaphase stage. Hence, the correct answer is option B.
.......... results in division of a cell into four cells.
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0%
Mitosis
0%
Interphase
0%
Prophase
0%
Meiosis
Explanation
Meiosis is a type of cell division which mostly takes place in reproductive cells. It is known as reductional division, which creates haploid cells having half the number of chromosomes as compared to the parent cell. It occurs in two stages meiosis I and meiosis II. Meiosis I is a reductional division while meiosis II is an equational division. So, when a single cell enters the meiotic cycle it forms two haploid cell after meiosis I which further forms four haploid cell after meiosis II.
So, the correct answer is option D.
When synapsis is complete all along the chromosome, the cell is said to have entered a stage called as
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0%
Zygotene
0%
Pachytene
0%
Diplotene
0%
Diakinesis
Explanation
Zygotene is marked by beginning of lateral pairing of homologous chromosomes at the chromosomal tips and its process along the length of chromosomes that is the formation of synaptonemal complex.
Pachytene is marked by completion of lateral pairing of homologous chromosomes along the entire length of chromosome and crossing over.
Diplotene is marked by breaking of synaptonemal complex, which holds the synapsed chromosomes together, which in turn causes separation of synapsed chromosomes all along their length except for the point of crossing over (chiasmata).
Diakinesis is marked by separation of homologous chromosomes at chiasmata as well.
So, the correct answer is option B.
Many cells can function properly and divide mitotically in absence of
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Plasma membrane
0%
Cytoskeleton
0%
Mitochondria
0%
Plastids
Explanation
Plasmalemma/cell membrane is the biological membrane that separate the cell’s interior from surrounding and from other cells. It serves as selective permeable membrane and maintains cell’s identity and integrity and therefore is indispensible part of any type of cell.
Mitochondria are double membrane bound eukaryotic cell organelles that serve as site for cellular respiration, produce enormous amount of energy to metabolic process and cell division.
Microtubules of cytoskeleton are the structural units of spindle fibres that become attached to chromosomes via kinetochores, present on the surface of chromosomal centromere, and move the chromosomes apart during cell division.
Plastids are double membrane bound organelles which are found in plant cells and other autotrophic organisms only and serve mainly in photosynthesis. They don’t contribute in cell division.
So, the correct answer is option D.
Which one of the following precedes re-formation of the nuclear envelope, during M phase of the cell cycle?
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Decondensation from chromosomes and reassembly of the nuclear lamina
0%
Transcription from chromosomes and reassembly of the nuclear lamina
0%
Formation of the contractile ring and formation of the phragmoplast
0%
Formation of the contractile ring and transcription from chromosomes
Explanation
The nuclear envelope in eukaryotes separates the DNA, from the cytoplasm disassembles. The chromosomes align themselves, in a line spanning the cell. Microtubules, essentially miniature strings, pulls out from opposite ends of the cell and shorten, pulling apart the sister chromatids of each chromosome. As a matter of convention, each sister chromatid is now considered a chromosome, so they are renamed to sister chromosomes. As the cell elongates, corresponding sister chromosomes are pulled toward opposite ends. A new nuclear envelope forms around the separated sister chromosomes.
so, the correct answer is option A.
During which stages (or prophase I substages) of meiosis, where do you expect to find the bivalents and DNA replication respectively?
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Pachytene and interphase (between two meiotic divisions).
0%
Pachytene and interphase (Just prior to prophase I).
0%
Pachytene and S phase (of interphase just prior to prophase I).
0%
Zygotene and S phase (of interphase prior to prophase I).
Explanation
In bivalent formation of chromosomes during meiosis, the homologous chromosomes are arranged in pairs. The phenomenon is called as synapsis and it occurs during zygotene stage. DNA replication occurs during S phase or synthetic phase which is the second phase of inter phase.
The correct sequence of the substages of prophase I is
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Diakinesis$$\rightarrow$$ Pachytene$$\rightarrow$$ Diplotene$$\rightarrow$$ Zygotene$$\rightarrow$$ Leptotene
0%
Leptotene$$\rightarrow$$ Zygotene$$\rightarrow$$Pachytene$$\rightarrow$$Diplotene$$\rightarrow$$Diakinesis
0%
Pachytene$$\rightarrow$$Zygotene$$\rightarrow$$Leptotene$$\rightarrow$$Diplotene$$\rightarrow$$Diakinesis
0%
Leptotene$$\rightarrow$$ Zygotene$$\rightarrow$$Diplotene$$\rightarrow$$Diakinesis$$\rightarrow$$ Pachytene
Explanation
Prophase 1 of meiosis is the first stage of meiosis and is defined by five different phases- leptotene, zygotene, pachytene, diplotene and diakinesis. Leptotene is the first of five stages of Prophase 1. Second stage is zygotene. Third and fourth is pachytene, diplotene respectively. The last one is diakinesis.
So, the correct answer is '
Leptotene
→
→
Zygotene
→
→
Pachytene
→
→
Diplotene
→
→
Diakinesis'
The chromosomes are arranged along the equator during
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0%
Prophase
0%
Metaphase
0%
Anaphase
0%
Telophase
Explanation
During metaphase, chromosomes are arranged on a plane, which is known as equatorial plate. It is the second stage of cell division (mitosis or meiosis), in which the chromosomes, each consisting of two chromatids, are arranged on the equatorial plane of the spindle prior to the separation.
The longest phase of meiosis is
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0%
Prophase I
0%
Prophase II
0%
Ansphase I
0%
Metaphase II
Explanation
Correct option: A
Explanation:
Like mitosis, the first meiotic division is studied under four phases. These are prophase I, metaphase I, anaphase I and telophase I.
In prophase I, there are five sub-phases:
Leptotene- T
he first stage of the prophase of meiosis, during which each chromosome becomes visible as two fine threads (chromatids).
Zygotene-
The
stage
in
the
prophase
of
meiosis
during
which
homologous
chromosomes
become
paired. This pairing of homologous chromosomes is called synapsis.
Pachytene- In pachytene, there occurs exchange of the corresponding segments non-sister chromatids of homologous chromosomes. This process is called crossing over.
Diplotene-
A stage of meiotic prophase in which homologous chromosome pairs begin to separate and chiasmata become visible.
Diakinesis-
This stage is recognized by the highly condensed condition of the chromosomes, the homologous
pair of which are held together by chiasmata
. In some organisms, just before or during diakinesis, the chiasmata move to the ends of the chromosome arms (terminalization of chiasmata).
Due to numerous substeps, prophase-I is the longest phase.
Meiosis is completed in how many stages?
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0%
1
0%
2
0%
10
0%
4
Explanation
Meiosis is carried out in two steps i.e meiosis I and meiosis II. Each step having 5 stages viz. prophase, metaphase, anaphase, telophase and cytokinesis.
The chromosome of .......... is one of the main tools in cancer studies.
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0%
Metaphase
0%
Anaphase
0%
Telophase
0%
Prophase
Explanation
A chromosome is composed of DNA and proteins. DNA are the hereditary units which mainly carries the information from one generation to the other. The functional segments of the DNA are known as genes. Proteins are mainly present as histones which form a complex structure known as a nucleosome.
The analysis of metaphase chromosomes is one of the main tools of classical cytogenetics and cancer studies. Chromosomes are condensed (thickened) and highly coiled in metaphase, which makes them most suitable for visual analysis. So, the correct answer is option A.
Which of the following is not a characteristic of meiosis?
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It involves two stages of DNA replication one before meiosis I and another before meiosis II.
0%
It involves recombination and crossing over.
0%
Sister chromatids separate during anaphase II.
0%
Nuclear membrane disappears during prophase.
Explanation
DNA replication occurs once but meiosis has two M-phases each with its own karyokinesis and cytokinesis. As a result chromosome number is halved. The transition period between M-phase I (meiosis I) and M-phase II (meiosis II) is short and without DNA replication. It is called interkinesis.
So, the correct answer is option A.
Synapsis occurs in what stage of Prophase I of meiosis I ?
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0%
Lepotene
0%
Zygotene
0%
Diplotene
0%
Pachytene
Meiosis leads to _______
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Genetic recombination
0%
Variations
0%
Evolution
0%
All of the above
Explanation
In meiosis I, Pachytene stage crossing over takes place between non-sister chromatids of homologous chromosomes. This leads to genetic recombination and thus variations and ultimately it leads to Evolution.
Correct option is D
Select the correct statement related to mitosis.
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Amount of DNA in the parent cell is first halved and then distributed into two daughter cells
0%
Amount of DNA in the parent cell is first doubled and then distributed into two daughter cells
0%
Amount of DNA in the parent cell is first halved and then distributed into four daughter cells
0%
Amount of DNA in the parent cell is first doubled and then distributed into four daughter cells
Explanation
Mitosis is a type of cell divison. There are two daughter cells formed at the end of mitosis. The amount of DNA in the parent cell is doubled in the S-phase of the interphase. There is breaking of the chromosomes and the chromosomes migrate to different poles during the anaphase. The DNA is equally distributed in the two daughter cells.
Thus, the correct answer is option B.
In cell cycle, during which phase, chromosomes are arranged in equatorial plate?
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0%
Metaphase
0%
Anaphase
0%
Telophase
0%
Prophase
Explanation
Prophase is the stage of mitosis, which is characterized by spindle formation, shortening and thickening of chromosomes, the disintegration of the nuclear envelope and disappearance of the nucleolus.
Metaphase proceeds prophase and is marked by the movement of chromosomes towards the equator of cell mediated by kinetochore microtubules of spindle fibres. Alignment of chromosomes on the equatorial plane of the spindle, the metaphase plate, marks the end of metaphase.
Anaphase is the stage of mitosis which is characterized by separation of sister chromatids followed by their movement towards the opposite pole of the spindle.
Completion of separation of sister chromatids, which are now present at the opposite poles of cell marks telophase. The cell resumes the interphase state during telophase.
So, the correct answer is option A.
In cell division, spindle fibres are made up of protein
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0%
Myoglobin
0%
Tubulin
0%
Albumin
0%
Myosin
Explanation
Spindle fibres are the cytoskeletal structure of eukaryotic cells, that are formed during cell division. It contracts and expands to separate sister chromatids between daughter cells. It is made up of microtubules, which are composed of protein tubulin. In cilia, the microtubules are arranged in 9+2 arrangement.
For the given diagram, a single chromosome is represented by part
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0%
A
0%
B
0%
C
0%
D
0%
E
Explanation
A single chromosome is a structure which, contains condensed chromatin material composed of DNA with a central constriction known as centromere. The functional part of the chromatin thread is known as genes.
Here, in the given diagram part A shows a single chromosome. So, the correct answer is option A.
Which among the following is a stage of meiosis during which recombination of genetic material occurs?
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Anaphase II
0%
Metaphase I
0%
Prophase II
0%
Metaphase II
0%
Prophase I
Explanation
Crossing over is the process of exchange of genetic material between non-sister chromatids of homologous chromosomes to produce new genetics combinations or variations. it takes place during pachytene of prophase I of meiosis I.
Since meiosis II is similar to that of mitosis, no recombination takes place during any of its stages.
Metaphase I is marked by the movement of pairs of homologous chromosomes towards the equator and their arrangement on it.
Therefore, the correct answer is option E.
Which of the following stages marks the reverse effect of prophase and prometaphase?
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0%
Metaphase
0%
Anaphase
0%
Both A and D
0%
Telophase
Explanation
During telophase, the effects of prophase and prometaphase are reversed. Two daughter nuclei form in each daughter cell, and phosphatases de-phosphorylate the nuclear lamins at the ends of the cell, forming nuclear envelopes around each nucleus. Therefore, the correct answer is option D.
The pairing of homologous chromosomes takes place in ..................... phase.
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0%
Anaphase I
0%
Prophase I
0%
Anaphase II
0%
Prophase II
0%
Metaphase I
Explanation
The prophase I of meiosis I is marked by synapsis of homologous chromosomes and crossing over. Zygotene of prophase I is marked by pairing of homologous chromosomes. Metaphase I is marked by movement of pairs of homologous chromosomes towards equator and their arrangement on it. The condensation of chromatin and appearance of chromosomes with sister chromatids takes place during prophase II. Metaphase II is marked by arrangement of chromosomes (each with two sister chromatids) on cell's equator which are then separated by splitting of centromere and move towards opposite poles during anaphase II.
Therefore, the correct answer is option B.
The cytoplasm divides at
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0%
Mitosis
0%
Prophase
0%
Cytokinesis
0%
Interphase
0%
Metaphase
Explanation
Cytokinesis involves the division of cytoplasm after karyokinesis. It mainly starts at anaphase but continues till telophase. During telophase, a nuclear membrane forms around each set of chromosomes to separate the nuclear DNA from the cytoplasm. The chromosomes begin to uncoil, which makes them diffuse and less compact. Along with telophase, the cell undergoes a separate process called cytokinesis that divides the cytoplasm of the parental cell into two daughter cells. In the animal cell the cytokinesis takes place by formation of furrow while, phragmoplast formation takes place in plants.
So, the correct answer is option C.
The various phases of the cell cycle will be affected by limiting growth factors like
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0%
Sufficient nucleotides
0%
Temperature
0%
Nutrients
0%
All of the above
Explanation
Different phases of the cell cycle will be affected by limiting growth factors such as nutrient supply, temperature, and room for growth.
Sufficient nucleotides and amino acids must be present in order to synthesize mRNA, proteins and to replicated DNA.
Physiological temperatures are optimal for cell growth so that enzymes involved in the cell cycle can work efficiently. In humans, the normal physiological temperature is around $$37^0 C$$.
Therefore, the correct answer is option D.
During which phase of meiosis do homologous chromosomes separate?
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Anaphase I
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Prophase I
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Anaphase II
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Prophase II
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Metaphase I
Explanation
The prophase I of meiosis I is marked by synapsis of homologous chromosomes and crossing over. Metaphase I is marked by the movement of pairs of homologous chromosomes towards the equator and their arrangement on it. Anaphase I is marked by separation of homologous chromosomes and their movement towards opposite poles. The condensation of chromatin and appearance of chromosomes with sister chromatids takes place during prophase II. Metaphase II is marked by the arrangement of chromosomes (each with two sister chromatids) on cell's equator which is then separated by splitting of centromere and move towards opposite poles during anaphase II.
Therefore, the correct answer is option A.
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