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CBSE Questions for Class 11 Medical Biology Cell Cycle And Cell Division Quiz 11 - MCQExams.com
CBSE
Class 11 Medical Biology
Cell Cycle And Cell Division
Quiz 11
Choose the correct answers from the alternatives given :
The two daughter cells formed during mitosis contain
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the same amount of DNA, but a set of chromosomes different from those of the parent cell
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the same amount of DNA and the same set of chromosomes as those of the parent cell
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half the amount of DNA and the same set of chromosomes those of the parent cell
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double the amount of DNA and a set of chromosomes different from those of the parent cell
Explanation
The mitosis division is the equitorial division which takes place in the cells which are not taking part in the reproduction
The cells after the division form 2 daughter cells which are identical to the mother cell in every aspect.
This type of division takes place in each and every organ of the body expect for the formation of gametes. For example mature cells of organs, wear and tear of the cells of epithelium, etc.
The genetic material of the cells is doubled during the S phase of the cell cycle where the genetic material is replicated. So that the genetic material can be equally divided between the 2 daughter cells.
Therefore the answer that the 2 daughter cells contain equal genetic as the mother cell is correct. So the answer option 'the same amount of DNA and the same set of chromosomes as those of the parent cell' is correct.
Choose the correct answers from the alternatives given :
Which statement best explains the evolutionary advantage of meiosis?
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Meiosis is absolutely necessary for sexual reproduction
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Meiosis alternates with mitosis from generation to generation
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Genetic recombinations are possible
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The same genetic system is passed from one generation to another
Explanation
Meiosis is the reduction division where the cell after dividing produces 4 daughter cells each having half the genetic material compared to the mother cell.
This kind of division takes place in the formation of the gametes which are required for reproduction.
The gametes are haploid as in sexual reproduction 2 type of gametes are required where both are haploid and when they fuse they form a diploid zygote.
Sexual reproduction is important from the evolutionary point of view as the during the formation of the zygote the gametes from both the parents are fused and the zygote will acquire the characteristics of both the parents .
Thus the offspring will have characters from both the parents as well new characters may be formed because of both the genetic material coming together.
Also during meiosis 1 in the prophase the chromosomes go under the process of crossing over where the genetic material between the non sister chromatids is exchanged this provides for the chances of genetic recombination thus forming variation in the genetic material.
Therefore the answer option 'Genetic recombinations are possible' is correct.
Homologous chromosomes segregate during
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Fertilization
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Meiosis I
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Meiosis II
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Mitosis
Explanation
Meiosis I is the division in which the genetic content reduces to half because the homologous chromosomes start moving to opposite poles.
So the correct answer is 'Meiosis
I'.
After mitosis, the chromosome number of a daughter cell is ……... that of the parent cells
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Doubled compared to
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One-half
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The same as
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Rearranged compared to
Explanation
Mitosis is the cell division which takes places in the cells of the whole body other than the cells that produce the gamete.
Before mitosis the genetic material of the cell is duplicated so that when the cell undergoes division the genetic material of the cell is equally divided and given to both of the daughter cells at the time of separation of the chromosomes that is the anaphase.
After the cell division is over both the daughter cells will have the same number of chromosomes as that of the mother.
Therefore the answer option 'The same as' is correct.
Choose the correct answers from the alternatives given :
It is important that the centromere does not divide until the end of metaphase because it
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contains the genes that control prophase
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holds the replicated DNA molecules together
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is connected to the nuclear membrane
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produces the spindle fibres
Explanation
The DNA that was replicated during the Sphase of the interphase are held together by the centromere till the chromosome are detached from each other to be pulled towards the poles of the dividing cells.
Metaphase is the second phase of the mitosis where the chromosomes after the condensation and disappearance of the nuclear membrane are lined at the metaphase or the equatorial plate in the middle of the dividing cell
At the end of the metaphase the spindle fibers from the centrioles are attached to the kinetochore which are present beside the centromere in the middle of the chromosome.
So when the chromosomes are pulled towards the poles in the anaphase the centromere are not required to hold the chromosomes together and so the centromere are also divided but at the end of the metaphase where the chromosomes are ready to be pulled towards the pole of the dividing cells.
Therefore the correct answer is option 'holds the replicated DNA molecules together'.
State the following statements are true or false.
In mitotic metaphase, the centromeres of chromosomes remain directed towards the poles and chromosomal arms remain directed towards the equator.
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True
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False
Explanation
In the metaphase stage, the centromeres are directed towards the poles and the arms are directed towards the equatorial plane.
So, the correct statement is '
In mitotic metaphase, the centromeres of chromosomes remain directed towards the poles and chromosomal arms remain directed towards the equator
'.
State the following statements are true or false.
The most significant feature of mitosis is the reduction of karyotypic number of chromosomes to half.
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True
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False
Explanation
Mitosis refers to the equal and same division of cells as their parent cell.
Cell division gives rise to genetically identical cells in which the number of chromosomes is maintained. Meiosis on the other hand is a type of division
that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes.
So, the correct option is 'False'.
State the following statements are true or false.
In mitosis, all chromosomes become aligned at the spindle equator at the end of anaphase
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True
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False
Explanation
The diagram shows the alignment of the chromosomes on the equatorial plane during the metaphase stage of the mitosis.
So, the correct statement is '
In mitosis, all chromosomes become aligned at the spindle equator at the metaphase
'.
State the following statements are true or false.
In metaphase, the sister chromatids move towards the opposite poles of the spindle.
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True
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False
Explanation
Metaphase is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage. These chromosomes, carrying genetic information, align in the equator of the cell before being separated into each of the two daughter cells. The chromosomes move towards the opposite poles of the spindle during anaphase.
So, the correct option is 'False'.
Select the correct option:
During anaphasic movements of chromosomes, ______ of each chromosome is/are towards the pole and _____ of the chromosome trail(s) behind.
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Centromere, arms
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Arms, centromere
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Chromatids, centromere
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None of these
Explanation
In the anaphasic movement of chromosomes, the centromeres lead the path while the arms trail behind. As a result, the anaphasic chromosomes appear V-, L-,J- and I shaped. The shapes are formed respectively in metacentric, submetacentric, acrocentric and telocentric chromosomes.
So, the correct answer is 'Centromere, arms'.
Select the correct option:
_______ is the best stage to count the number and study the morphology of chromosomes.
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Prophase
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Metaphase
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Anaphase
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Telophase
Explanation
Metaphase is the best phase to count total number of chromosomes in any species and detailed study of the morphology of chromosome. Idiogram (arrangement of chromosomes in a series of decreasing length ) can be drawn in This stage.
So, the correct answer is 'Metaphase'.
Human cells in culture show a cell cycle to be completed in approximately
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42 hours
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24 hours
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24 minutes
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24 seconds
Explanation
Cell division is the process by which a cell divides to form to nearly equal daughter cell which resembles the parent.
The cell cycle is the sequence of events which occur during the cell growth and cell division. It is completed into two steps interphase and M-phase.
In the cell cycle interphase is the period between the end of one division to the beginning of next cell division. It is known as the resting phase. In the case of human beings it is
around
24 hours then the M phase takes place.
So, the correct option is '24 hours'
At which stage of mitosis, the two daughter chromatids separate from each other, migrate towards the opposite poles and are now referred to as chromosomes of the future daughter nuclei?
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Prophase
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Metaphase
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Anaphase
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Telophase
Explanation
In anaphase, the centromeres of chromosomes start to divide into two, forming daughter chromosomes with centromere in each. Daughter chromosomes are repulsive so they migrate toward opposite poles. Spindle fibres attached to the centromeres shorten and pull the chromosomes to the poles.
So, the correct answer is 'Anaphase'.
A diploid cell which consist 46 chromosomes, than how many bivalant or tetrad found in Zygotene
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46
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23
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92
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None
Explanation
A bivalent, sometimes referred to as a tetrad, is the association of a pair of homologous chromosomes physically held together by at least one DNA crossover. So 46 chromosomes will make 23 pairs and further form 23 bivalent or tetrads.
So the correct answer should be option "23".
During cell division, the spindle fibres get attached to condensing chromosome at a highly differentiated region. This region is called as
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Chromosome
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Chromocentre
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Centriole
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Kinetochore
Explanation
The key feature of metaphase is the attachment of spindle fibers to kinetochores of chromosomes. Kinetochores are disc-shaped structure at the surface of the centromeres. These structures serve as the site of attachment of spindle fibres to the chromosomes that are moved toward poles.
So, the correct answer is 'Kinetochore'.
You are provided with floral buds of Chrysanthemum in your class and are asked to count the chromosomes, then which of the following stages would you prefer to look into?
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Prophase
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Metaphase
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Anaphase
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Interphase
Explanation
Metaphase is the best phase to count total number of chromosomes in any species and detailed study of the morphology of chromosome. Idiogram (arrangement of chromosomes in a series of decreasing length ) can be drawn in his stage.
So, the correct answer is 'Metaphase'.
In onion root tip during metaphase stage of mitiosis the number of kinetochores will be -
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4
0%
8
0%
16
0%
32
Explanation
The state of the cell in metaphase stage of mitosis in root tip is diploid that is 2n, so there is 16 chromosome in root tip of onion as n is 8. But each chromosome contains 2 kinetochores, so the number of kinetochores in metaphase stage of mitosis is 32.
So, the correct option is D.
Mitosis characterised by
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Reduction division
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Equal division
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Both reduction and equal division
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Pairing of homologous chromosomes
Explanation
Mitosis is a type of cell division in which chromosomes replicate and become equally distributed (quantitatively and qualitatively) into two daughter nuclei so that the daughter cells come to have the same number and type of chromosomes as are present in the parent cell.
Match column I with column II and select the correct option from the given codes.
Sr. No
List I
Sr.No
List II
A.
Division of nucleus
1.
Interphase
B.
Division of cytoplasm
2.
Cytokinesis
C.
DNA replication
3.
Syncytium
D.
Karyokinesis not followed by cytokinesis
4.
Karyokinesis
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A-(iii),B-(ii),C-(i),D-(iiv)
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A-(iv),B-(ii),C-(i),D-(iii)
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A-(iii),B-(iv),C-(i),D-(ii)
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A-(i),B-(ii),C-(iii),D-(iv)
Explanation
The cell cycle is the sequence of events which occur during cell growth and cell division. It is divided into two phases- interphase which is the non-dividing phase and M-phase which is the mitotic phase. M phase generally divided into two phases karyokinesis and cytokinesis. Cytokinesis is the division of cytoplasm and karyokinesis is the division of the nucleus. If karyokinesis is not followed by cytokinesis then in this condition the cell has many nuclei and is known as a syncytium. During the interphase the replication of DNA contents takes place.
Thus, the correct answer is 'A-(iv),B-(ii),C-(i),D-(iii).'
Meiosis consists of
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Two cell divisions without any DNA replication
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Two cell divisions in which chromosome number in reduced to half
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Two cell divisions with only two rounds of chromosome replication
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A single cell division with chromosome replication.
Explanation
Meiosis is a double division that occurs in the reproductive cell in which nucleus divide but chromosome replicate only once to form four haploid cells, each cell having half the number of chromosomes present in a parent cell. It causes a reduction in the number of chromosomes. It is also known as reduction division.
Meiosis in a cell occurs only once to form gametes.
Thus, the correct answer is 'Two cell divisions in which chromosome number is reduced to half.'
Select the incorrect match regarding mitotic cell division.
(i) Prophase - Chromosomes to begin to uncoil
(ii) Metaphase - Chromatids move apart
(iii) Telophase - The nuclear membrane reappears
(iv) Late anaphase- Each chromosome consists of two anaphase chromatids
(v) Interphase - Chromosomes are not distinct
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(ii) and (iv) only
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(i) and (iii) only
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(ii), (iv) and (v) only
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(ii) and (v) only
Explanation
Prophase is the first stage when the chromosome begins to uncoil and chromatin is seen. In the metaphase all the chromosome from a single plate. In metaphase on the equatorial plate, chromosome appears as two threaded. during the telophase, the nuclear membrane starts reappearing and the chromosomes disappear.
The interphase is the stage between two dividing phases and the chromosomes are not distinct.
In the late anaphase is chromosome consists of chromatids as they are present on to separate poles.
So, the correct option is '(ii) and (iv) only'
Select the correct match.
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Quiescent phase - $$G_2$$ phase
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Synthesis phase - $$G_1$$ phase
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Centromere splitting - Anaphase
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Chromosomal condensation - Metaphase
Explanation
Anaphase is the phase of mitosis which takes place after prophase and metaphase.
In anaphase, the centromere split from the middle and two chromatids get separated. Both chromatids move toward opposite poles due to repulsive forces which are known as anaphasic movements. Anaphasic movements are brought about by the repolymerization of continuous fibres and depolymerization of chromosomal fibres.
So, the correct option is 'Centromere splitting - Anaphase'
Spindle usually persists in the form of ______ during _____ method of cytokinesis.
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phragmoplast, cleavage
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phragmoplast, cell plate
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cell plate, cell plate
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cell plate, cleavage
Explanation
Cell plate method is a characteristic method of cytokinins of the plant cell. Here the vesicles provided by the Golgi apparatus unite to phragmoplast and they unite to form the cell plate. The cell plate is first laid down in the centre and then proceed towards periphery that is the centrifugal plate formation. Cell wall materials and now laid down on both side of the cell plate and thus forming two daughter cells.
So, the correct option is 'phragmoplast, cell plate'
The role of mitosis is not merely to divide a cell into two daughter cells but to ensure genetic continuity from one cell generation to another cell generation. The mechanism ensuring genetic continuity is
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Formation of cells with new chromosomes
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Formation of two daughter cells
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Formation of two cells with identical DNA
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Halving the chromosome number between the two new cells.
Explanation
All the daughter cells of multicellular organism have the same number and type of chromosomes as parent cells due to equitable distribution of all chromosomes in mitosis. This helps in ensuring genetic continuity.
So, the correct answer is 'Formation of two cells with identical DNA'.
What is true about telophase stage of mitosis?
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Chromosomes lose their identity as discrete elements.
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Chromosomes cluster at opposite spindle poles.
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Nuclear envelope, nucleolus, Golgi complex and ER reform.
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All of these
Explanation
During telophase the individual chromosomes are no longer seen and chromatin material tends to collect in a mass at the two poles. Chromosomes cluster at opposite spindle poles and their identity is lost as discrete elements Nuclear envelope assembles around the chromosome clusters. Nucleolus, Golgi complex and ER reform.
So, the correct answer is 'All of these'.
Which phase of mitosis is essentially the reverse of prophase in terms of nuclear changes?
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S - phase
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Anaphase
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Telophase
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Interphase
Explanation
During telophase of mitosis viscosity of cytoplasm decreases. A new nuclear membrane is formed (either from older nuclear envelope or ER) around each set of chromosomes. Chromosomes overlap farming chromatin. The nucleolar organiser region of satellite chromosomes produce nucleolus for each daughter nucleus. Nucleoplasm surrounds in the area of chromatin. The gel state of spindle is converted into sol state and disappears. In this way two daughter nuclei are formed at the poles of spindle. Hence this phase is just reverse of prophase.
So, the correct answer is 'Telophase'.
Select the correct option:
A cell's division time is 1 minute In 20 minutes, a culture tube (culture medium) is $$1/8^{th}$$ filled with cells, When the tube will be fully filled?
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21 minutes
0%
23 minutes
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60 minutes
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160 minutes
Explanation
In $$20$$ mins, culture tube is $$1/8th$$ filled with cells. Each cell divides every minute producing two daughter cells.
Hence, in $$21$$ min =$$\dfrac{1}{8} \times 2 = \dfrac{1}{4}$$
In $$22$$ min $$\dfrac{1}{4}\times 2=\dfrac{1}{2}$$
In $$23$$min $$\dfrac{1}{2}\times 2=1$$
That means in 23 minutes, the culture tube will be completely filled.
So, the correct answer is '23 minutes'.
If a tissue has at a given time 1024 cells, how many cycles of mitosis had the original parental single cell undergone?
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512
0%
10
0%
1024
0%
256
Explanation
Correct option: B
Explanation:
The correct answer is Option B- '10'.
Each Mitosis cycle produces 2 daughter cells. It is calculated by the formula $$(2^n)$$
Where n =number of cycles).
$$2^n$$ = 1024 daughter cells
n = 10.
Cell plate formation during Karyokinesis takes place due to the action of
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Lysosomes and endoplasmic reticulum
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Lysosomes and mesosomes
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Golgi bodies and endoplasmic reticulum
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Mesosomes and mitochondria
Explanation
During interphase, the Golgi apparatus accumulates enzymes, structural proteins ( synthesized by R enodplasmic reticulum ), and glucose molecules prior to breaking into vesicles and dispersing throughout the dividing cell. During telophase, these Golgi vesicles are transported on microtubules to form a phragmoplast (a vesicular structure) at the metaphase plate. There, the vesicles fuse and coalesce from the center toward the cell walls; this structure is called a cell plate. So, the correct option is C. ( Golgi bodies and endoplasmic reticulum )
Select the correct option:
The figure given below shows a cell undergoing meiosis.
Which of the options below shows the next stage in the process?
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0%
0%
0%
Explanation
Prophase is the longest phase of karyokinesis of meiosis and it is divided into 5 phases. Leptotene is the stage where the chromosome appears as a long thread with chromomeres on it. Then we have zygotene where bivalents or tetrads are seen are seen. Pachytene is the state where the crossing over and the formation of recombinant nodules takes place. Diplotene is a stage where the chiasmata and the X-shaped structure are seen.
Diakinesis is the where terminalisation takes place.
Then in the next phase that is the metaphase I the chromosome arrange itself on the metaphase plate.
So, the correct option is 'B'
Best material to study meiosis is __________
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Root tip
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Ovary
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Young anther
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Pollen grain
Explanation
Meiosis takes place in reproductive organs. It results in formation of gametes with half the normal chromosome number. Young anthers are the best materials to study meiosis. So, the correct is 'Young anther'.
Which of the following is not a feature of meiosis?
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Meiosis involves two sequential cycles of nuclear and cell division, meiosis I and meiosis II but only a single cycle of DNA replication.
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Meiosis I is initiated after the parental chromosomes have replicated to produce identical sister chromatids at the S - phase.
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Meiosis involves pairing of non-homologous chromosomes and recombination between them.
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Four haploid cells are formed at the end of meiosis II.
Explanation
Meiosis, as we know, is called as Reductional division where the number of chromosomes is reduced to half from parent to daughter cell. It involves two cycles - Meiosis I and Meiosis II where nuclear and cell division takes place but DNA replication takes place once only. While meiosis I take place after the cell has completed the replication of DNA of parent material and thus identical sister chromatids is formed. While since it is a reductional division so we know four daughter cells are formed having half the number of chromosomes as of parent cell. Moreover, Meiosis never involves the pairing of non-homologous chromosomes and no recombination occurs between them.
So, the Incorrect statement with respect to meiosis is 'Meiosis involves the pairing of non-homologous chromosomes and recombination between them.'.
Which of the following correctly shows a pair of homologous chromosomes at the start of meiosis?
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0%
0%
0%
0%
Explanation
Homologous chromosomes are that chromosome that appears similar in shape and size and they form pairs which are known as bivalents or tetrads, during zygotene stage of prophase I
So, the correct option is 'D'
Which of the following is correct about bivalent?
(i) Bivalents are tetrads.
(ii) A bivalent means 4 chromatids and 2 centromeres.
(iii) One bivalent consists of 2 homologous chromosomes.
(iv) Bivalents form in zygotene.
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(i), (ii), (iii) and (iv)
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(iii) only
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(iii) and (iv)
0%
(iv) only
Explanation
During the Prophase I of meiosis I the paring of homologous chromosomes takes place in the zygotene substage, in this phase the chromosomes appear to have two chromatids each, attached by a centromere. Therefore the homologous pair appears to have two centromeres and four chromatids also referred to as the bivalents or the tetrads.
So, the correct answer is '
(i), (ii), (iii) and (iv)'
Match column I with column II and select the correct option from the given codes.
Sr. no
List I
Sr.no
List II
A.
Chromosomes move to equator
1.
Pachytene
B.
Centromere splits and chromatids move apart
2.
Zygotene
C.
Pairing between homologous chromosomes
3.
Anaphase
D.
Crossing over between homologous chromosomes
4.
Metaphase
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A-(i),B-(ii),C-(iv),D-(iii)
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A-(ii),B-(iii),C-(iv),D-(i)
0%
A-(iv),B-(iii),C-(ii),D-(i)
0%
A-(iv),B-(ii),C-(i),D-(iii)
Explanation
Meiosis has the prophase stage which is the longest phase of karyokinesis otherwise. It is then divided into five different phases. Leptotene is the phase where the chromosomes are present as a long thread with chromomeres on it. Zygotene is the second stage where the pairing of synopsis of homologous chromosomes takes place here. In the stage. Pachytene is the stage where crossing over or exchange of segments between non-sister chromatids of homologous chromosomes takes place. Diplotene is the stage where the chromosome begins to separate and terminalization starts. Diakinesis is the stage where the nuclear membrane starts degeneration.
Metaphase is the stage where the chromosomes arrange themselves on the metaphase plate. Anaphase is the place where he the separation of the chromosomes takes lace and disjunction takes place.
Thus, the correct answer is 'A-(iv), B-(iii), C-(ii), D-(i).'
Match column I with column II and select the correct option from the given codes.
Sr.no
List I
Sr.no
List II
A.
Synaptonemal complex
1.
Pachytene
B.
Recombination nodule
2.
Zygotene
C.
Terminalisation of chiasmata
3.
Telophase I
D.
Formation of dyad cell
4.
Diakinesis
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A-(ii),B-(i),C-(iv),D-(iii)
0%
A-(i),B-(ii),C-(iv),D-(iii)
0%
A-(iii),B-(i),C-(iv),D-(ii)
0%
A-(ii),B-(i),C-(iii),D-(iv)
Explanation
Meiosis has the prophase stage which is the longest phase of karyokinesis otherwise. It is then divided into five different phases.
Leptotene
is the phase where the chromosomes are present as a long thread with chromosomes on it.
Zygotene
is the second stage where the pairing of synopsis of homologous chromosomes takes place here.
Pachytene
is the stage where the crossing over or exchange of segments between non-sister chromatids of homologous chromosomes takes place.
Diplotene
is the stage where the chromosome begins to separate and terminalization starts.
Diakinesis
is the stage where the nuclear membrane starts degeneration.
Thus, the correct answer is 'A-(ii), B-(i), C-(iv), D-(iii).'
At which of the following stages, the chromosomes appear single, thin and thread like?
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Leptotene
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Zygotene
0%
Pachytene
0%
Diplotene
Explanation
Leptotene also known as leptonema is the first stage of prophase I during which individual chromosomes begin to condense into long strands within the nucleus which are loosely interwoven. However, the two sister chromatids are still so tightly bound that they are indistinguishable from one another. They possess a string of. swollen areas called chromomeres.
So, the correct answer is option A.
Select the correct option:
Zygotene of prophase -I is characterised by
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chromomeres
0%
synaptonemal complex
0%
crossing over
0%
terminalisation of chiasmata
Explanation
During zygotene of meiotic prophase I, chromosomes start pairing and are called homologous chromosomes. A pair of homologous chromosomes lying together is called a bivalent. The complex formed by a pair of synapsed homologous chromosomes is called synaptonemal complex.
Reformation of nucleolus, golgi complex and ER occurs in
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Telophase
0%
Metaphase
0%
Prophase
0%
Anaphase
Explanation
During telophase, the nucleolus, ER and Golgi apparatus reappears.
During nuclear membrane and nucleolus reappears. daughter nuclei formation takes place.
So, the correct option 'Telophase'
Prophase of the first meiotic division is typically longer and complex. It is subdivided into $$5$$ phases: leptotene, zygotene, pachytene, diplotene and diakinesis. Which of the following statements is not correct of these phases?
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The formation of synaptonemal complex is seen during zygotene stage.
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The stage of pachytene is characterized by appearance of recombination nodules.
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Diplotene stage is marked by terminalisation of chiasmata.
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The compaction of chromosomes continues throughout the leptotene.
Explanation
Meiosis is the type of division in which a diploid cell divides to give rise to four haploid gametes. The terminalization of chiasmata takes place during the diakinesis stage of meiosis, not j the diplotene stage.
So, the correct answer is 'Diplotene stage is marked by terminalisation of chiasmata.'
Select the correct option:
Four different steps that occur during meiosis are given in the following list.
(i) Complete separation of chromatids
(ii) Pairing of homologous chromosomes
(iii) Lining up of paired chromosomes on equator
(iv) Crossing over between chromatids
Select the correct sequential arrangement of the steps.
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(ii), (iii), (iv), (i)
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(iii), (ii), (iv), (i)
0%
(ii), (iv), (iii), (i)
0%
(iii), (i), (ii), (iv)
Explanation
Pairing of homologous chromosomes occurs in zygotene and crossing over occurs in pachytene stage of prophase I of meiosis I. Paired chromosomes line up on equator in metaphase I. Then there is complete separation of chromatids in anaphase I of meiosis I.
So, the correct answer is '(ii), (iv), (iii), (i)'.
During meiosis I, chromosome number
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Is reduced to half
0%
Doubles up
0%
Remains the same
0%
Either A or B
Explanation
Meiosis is the type of cell division by which gamete cells (eggs and sperms) are produced. Meiosis involves two successive nuclear divisions and one cytoplasmic division that produce four haploid cells. The first division (meiosis) is the reductional division during which number of chromosomes is reduced to half. The second division (meiosis II) separates the chromatids. It is called equational division as chromosomes number remains the same as produced after meiosis I.
So, the correct answer is 'Is reduced to half'.
Meiosis does not occur in
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Asexually reproducing diploid individuals
0%
Sexually reproducing haploid individuals
0%
Sexually reproducing diploid individuals
0%
All of the above
Explanation
Meiosis is the process by which one diploid eukaryotic cell divides to generate four haploid cells often called gametes.
Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes that reproduce sexually.
Meiosis does not occur in archaea or bacteria, which reproduce via asexual processes such as mitosis or binary fission.
So, the correct option is '
Asexually reproducing diploid individuals'.
Select the correct option:
Refer to the given stages A, B, C and D of meiosis I and select the incorrect statement regarding them.
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The last stage of A diakinesis which is marked by terminalisation of chiasmata.
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In stage B, microtubules from the opposite poles of the spindle attach to the pair of homologous chromosomes.
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In stage C, homologous chromosomes separate, while sister chromatids remain associated at their centromeres.
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In stage D, nuclear membrane and nucleolus disappear, cytokinesis follows and this is called as dyad of cellls.
Explanation
In the given figure A, B, C, and D represent prophase I, metaphase I, anaphase I and telophase I, of meiosis I respectively. In telophase stage of meiosis I nuclear membrane and nucleolus reappear, cytokinesis follows and this is called dyad of cells.
So, the correct answer is 'In stage D, nuclear membrane and nucleolus disappear, cytokinesis follows and this is called as dyad of cells'.
A dikaryon is formed when-
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Meiosis is arrested
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The two haploid cells do not fuse immediately
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Cytoplasm does not fuse
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None of the above
Explanation
$$\textbf{Correct option:(B)}$$
$$\textbf{Explanation for correct option:}$$
$$\bullet$$ In
fungi such as ascomycetes and basidiomycetes
,
karyogamy is delayed and occurs just before meiosis.
$$\bullet$$
In the stage intervening between plasmogamy and karyogamy, the cells often contain two nuclei or dikaryon (n + n).
$$\bullet$$
Such cells are called dikaryotic cells. The phase is known as dikaryophase.
$$\bullet$$
Hence the correct option is (B)
Select the correct option:
If 2n = 4, then identify the figures A, B and C, as per the following codes and select the correct option.
Anaphase of meiosis I = (i)
Anaphase of mitosis = (ii)
Anaphase of meiosis ll = (iii)
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A - (ii), B - (i), C - (iii)
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A - (iii), B - (ii), C - (i)
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A - (i), B - (ii), C - (iii)
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A - (iii), B - (i), C - (ii)
Explanation
During anaphase or mitosis each chromosome arranged at metaphase plate is split and two daughter chromatids are formed. Centromeres split and chromatids move to opposite poles. During anaphase I of meiosis I, the homologous chromosomes separate, while sister chromatids remain associated at their centromeres. Anaphase II of meiosis II begins with a simultaneous splitting of the centromere of each chromosomes allowing them to move towards the opposite of the cell.
So, the correct answer is 'A - (ii), B - (i), C - (iii)'.
During meiosis I in humans, one of the daughter cells receives
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Only maternal chromosomes
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A mixture of maternal and paternal chromosomes
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Same number of chromosomes as present in parent cell
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None of the above
Explanation
During pachytene sub-stage of meiosis -I, crossing over i.e. exchange of genetic material take place between homologous chromosomes, which results in recombinations. The two homologous chromosomes are contributed by different parents. One of them is paternal chromosome and the other one is maternal chromosome.
So, the correct answer is 'A mixture of maternal and paternal chromosomes'.
Refer to the given figure and select the correct statement.
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In stage B homologous chromosomes are interconnected and chromosomes occur in pairs.
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Stage A is divisible into five substages.
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In stage D, chromosomes are not enclosed by a nuclear envelope.
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In stage C centromeres divide and chromosomes are single stranded.
Explanation
In the given figure A, B, C, and D represent prophase II, metaphase II, anaphase II and telophase II respectively. Prophase II is not divisible into substages rather prophase I is divisible into five substages. Chromosomes are free in metaphase II while in metaphase I homologous chromosomes are interconnected and chromosomes occur in pairs i.e., bivalents In telophase chromosomes get enclosed by a nuclear envelope.
The male gametes of rice plant have $$12$$ chromosomes in their nucleus. The chromosome number in the female gamete, zygote and the cells of the seedling will be, _________ respectively.
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$$12, 24, 12$$
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$$24, 12, 12$$
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$$12, 24, 24$$
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$$24, 12, 24$$
Explanation
Chromosome number in male gamete of rice plant is $$n = 12$$ therefore chromosome number in female gamete would also be $$12$$. Zygote is diploid as it is the product of fertilization and the cells of the seeding would be meiocytes and other diploid cells. Hence, the chromosome number in both zygote and cells of seeding will be $$2n = 24$$.
So, the correct answer is '12,24,24'.
Meiosis in diploid organism result in
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Production of gametes
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Reduction in the number of chromosomes
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Introduction of variation
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All of the above
Explanation
Meiosis is cell division responsible for production of gametes through reductional division which result in halving of the number of chromosomes. The crossing over that takes place in pachytene (prophase I , meiosis I) results in introduction of variation.
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Practice Class 11 Medical Biology Quiz Questions and Answers
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