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CBSE Questions for Class 11 Medical Biology Cell Cycle And Cell Division Quiz 4 - MCQExams.com
CBSE
Class 11 Medical Biology
Cell Cycle And Cell Division
Quiz 4
Genetic crossing over usually takes place during
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Meiosis I
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Mitosis
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Meiosis II
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Mitosis and meiosis I
Explanation
Living organisms show two types of cell division- mitosis and meiosis. The meiosis occurs in two stages meiosis I and meiosis II. Meiosis I is characterised by the pairing of homologous chromosomes, crossing over between homologous chromosomes and separation of homologous chromosomes, so that each daughter cell produced after meiosis I have one-half the chromosome number as compared to the parent cell.
So, the correct answer is option A.
If you are provided, with root-tips of onion in your class and asked to count the chromosomes, which of the following stages will be most conveniently observed?
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Metaphase
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Telophase
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Anaphase
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Prophase
Explanation
Chromosomes are tightly coiled, shortest and most clearly visible in metaphase stage neatly arranged on the metaphase plate at the equator of the cell. Hence, metaphase stage is best suited to study the number and morphology of the chromosomes.
So, the correct answer is option A.
Meiosis is important for evolution because of
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Recombination in somatic cells.
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Number of chromosomes in somatic cells become half.
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Formation of diploid eggs (gametes).
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Equational and reductional divisions.
Explanation
Meiosis produces haploid gametes. The haploid gametes are produced after crossing over between non sister chromatids of homologous chromosomes. This gives rise to new combinations of genetic material and creates diversity which ultimately is acted upon by natural selection. The meiosis occurs in two stages: meiosis I or reductional division and meiosis II or equational division. The reductional division is important for generating diversity and reducing the number of chromosomes to one half. The equational division is important for splitting of centromere and separation of sister chromatids, else the gametes will have double or bivalent chromosomes and when these gametes fuse the zygote will have all duplicated chromosomes even before the S phase. This will ultimately result in excess DNA and genetic mutations such as polyploidy.
HeLa cells used for the study of cell division, are
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Human skin cancer cells
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Human uterine cancer cells
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Human heart cells
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Rat uterine cancer cells
Explanation
A HeLa is a human cell line which is immortal in nature. It has the potential to survive longer and divide incessantly. The line was derived from cervical cancer cells taken on February 8, 1951, from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951.
The cells from Henrietta's tumor were taken by researcher George Gey, who "discovered that [Henrietta's] cells could be kept alive and grow indefinitely.
So, the correct answer is option B.
Synapsis occurs between
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Spindle fibres and centromere
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Two homologous chromosomes
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A male and a female gamete
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mRNA and ribosomes
Explanation
The meiosis is characterised by pairing of homologous chromosomes, crossing over and separation of homologous chromosomes. The pairing of homologous chromosomes is also called as synapsis. The synapsis results in exchange of segments between non sister chromatids of a homologous pair of chromosome. Because the homologous chromosomes separate, the chromosome number is reduced to one half during meiosis.
In meiosis I, the centromere undergoes
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Division between anaphase and interphase.
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Division between prophase and interphase.
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Division but the daughter chromosomes do not separate.
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No division.
Explanation
Meiosis occurs in two stages - meiosis I and meiosis II. The meiosis I is characterised by pairing of homologous chromosomes, crossing over and separation of homologous chromosomes. The centromere remains intact during meiosis I and homologous chromosomes separate. Thus, the number of chromosomes in progeny nuclei is reduced to one half. In meiosis II, just as mitosis, centromere separate and, hence, the number of chromosomes in the progeny remains same.
If 2n = 8, what shall be the number of chromatids in each daughter cell after meiosis 1?
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4
0%
16
0%
2
0%
8
Explanation
Meiosis I is reductional division. Hence if the mother cell has 8 chromosomes, after meiosis I the progeny cells will have 4 chromosomes or 8 chromatids.
If 2n = 14, (n = 7), then what will happen during meiosis?
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7 set of chromosomes will be passed to the offsprings from maternal side only.
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7 set of chromosomes will be passed to the offsprings from paternal side only.
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The characters will get mixed up and passed to offsprings.
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All of the above
Explanation
During meiosis, the homologous chromosomes pair and exchange segments then they are separated into separate gametes. If in a cell the diploid chromosome number is 14, during meiosis there will form seven pairs of homologous chromosomes. The two chromosomes in each of these seven pairs will exchange segments leading to mixing of characters. Following the exchange of segments, one chromosome from each of the seven pairs will be passed on two daughter cells which in turn will divide by the process of mitosis into two cells each giving rise to four haploid gametes. The haploid gametes will fuse and In the next generation mixed or crossed or jumbled or new combinations of characters will be passed on to progeny.
Mitosis and cytoplasmic division function in which of the following?
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Asexual reproduction of single cell eukaryote.
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Growth, tissue repair, often asexual reproduction.
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Gamete formation in reproduction.
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Both A and B
Explanation
Organisms basically show two types of cell division mitosis and meiosis. Meiosis is a specialized type of division in which chromosome number is reduced to half. Meiosis occurs in germ cell and forms gametes. Mitosis results in an increase in the number of cells. The chromosome number remains the same. Mitosis increase number of cells. It is useful in growth, tissue repair, and asexual reproduction.
So, the correct answer is option D.
The cell-division also known as reduction cell-division is
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Fission
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Meiosis
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Mitosis
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Amitosis
Explanation
Meiosis is a reductive cell division, whereby the number of chromosomes in the daughter cells is reduced by half, to produce haploid gametes (meiosis). Meiosis results in four haploid daughter cells by undergoing one round of DNA replication followed by two divisions, homologous chromosomes are separated in the first division, and sister chromatids are separated in the second division.
So, the correct answer is option B.
$$2n = 16$$ in a primary spermatocyte which is in metaphase of first meiotic division. What shall be the total number of chromatids in each of the secondary spermatocyte?
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32
0%
8
0%
16
0%
24
Explanation
Spermatogonium (2N) divides by mitosis and we get primary spermatocyte (2N) and by meiosis from one primary spermatocyte (2N), we get two secondary spermatocytes (N).
Now, the number of chromosomes present in secondary spermatocyte is N and in one chromosome, there are two sister chromatids.
So, if there are 16 chromosomes in primary spermatocyte, the secondary spermatocyte will have half the number i.e.; 8 chromsomes and the chromatids will be 8*2 = 16.
Thus, the correct answer is '16'.
During gamete formation, the enzyme recombinase plays active role during
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Prophase I
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Prophase II
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Metaphase I
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Anaphase II
Explanation
Meiosis occurs in two stages Meiosis I and Meiosis II. Crossing over and reduction in chromosome number occurs during meiosis I. The meiosis I is completed in stages like prophase I, metaphase I, anaphase I and telophase I. The prophase I is a very elaborate and complex stage. It comprises of leptotene, zygotene, pachytene, diplotene and diakinesis. The crossing over occurs in pachytene stage between non-sister chromatids of same bivalent. The crossing over is a complex enzyme catalysed process. The recombinase enzyme complex carries out crossing over in the pachytene sub-stage of prophase I stage of meiosis I of meiotic cell division.
So, the correct answer is option A.
The trigger protein, which is required by cell to pass through restriction point is
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T protein
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P protein
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U protein
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R protein
Explanation
The G$$_1$$ phase is marked by the synthesis of RNA, ribosomes and proteins and maximum growth occurs in this phase. Certain cytological conditions arise in G$$_1$$ phase, which is necessary to induce a cell to divide, otherwise the cell cycle is arrested or restricted. This restriction point occurs in late G$$_1$$ phase. Once the cell has passed restriction point, it will complete the rest of the cell cycle. Cells need to accumulate a certain level of trigger proteins, called U-proteins, in order to pass through this restriction point.
So, the correct answer is option C.
Which stages of cell division do the following figures A and B represent respectively?
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Prophase - Anaphase
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Metaphase - Telophase
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Telophase - Metaphase
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Late anaphase - Prophase
Explanation
Mitosis is the process of cell division which involves 4 different phases such as Prophase, Metaphase, Anaphase and, Telophase.
During the prophase, the duplicated DNA is compactly packed into chromosomes and spindle formation occurs as shown in the 2nd image.
In the metaphase stage, nuclear membrane disrupts and the condensed chromosomes align in the metaphase plate in right angles to the spindle poles.
At the anaphase stage, the chromosome pairs completely move to opposite poles with the the help of microtubules in the spindle apparatus. This is perfectly depicted in the 1st image.
During the telophase stage, the spindle fibres lengthens more and the nuclear membrane reforms to form the nuclei enclosing the separated sister chromatids. And, later followed by cytokinesis which involves the division of cytoplasm and yields the 2 daughter cells.
Therefore, the above images depict the late anaphase and the prophase,
During mitosis, endoplasmic reticulum and nucleolus begin to disappear at which of the following phase?
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Early prophase
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Late prophase
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Early metaphase
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Late metaphase
Explanation
Prophase is the most elaborate stage of cell division. Prophase is the longest of karyokinesis. In early prophase, chromatin condenses. In mid prophase, chromosomes shorten and become distinct with each having two chromatids attached to a narrow point called centromere. In late prophase, the centrosomes reach the poles, form asters and begin to develop spindle fibers. Endoplasmic reticulum and nucleolus along with major cell organelles degenerate.
So, the correct answer is option B.
In an eukaryotice cell number of chromosomes areAfter meiosis I and II, it results into 4 daughter cells. Then each daughter cell will have how many chromosomes?
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36
0%
18
0%
9
0%
27
Explanation
Meiosis is the reductional division. Meiosis results in reduction of chromosome number to one half in the normal diploid cell. Thus, if a cell has 36 chromosome before meiosis. After meiosis the four daughter cells produced will be having 18 chromosomes each.
Two chromatids of metaphase chromosome represents which of the following?
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Non-homologous chromosomes joined at centromere
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Maternal and paternal chromosome joined at centromere
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Replicated chromosomes to be separated at anaphase
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None of the above
Explanation
A normal cell cycle comprises of interphase (G$$_1$$ phase, S phase and G$$_2$$ phase) and M phase. During the S phase of interphase, the DNA duplicates due to replication. The duplication of DNA leads to the production of two chromatids joined at the centromere. The M phase comprises of prophase, metaphase, anaphase and telophase. The chromatin material coils into distinct structures called chromosomes in the prophase. In the metaphase stage, chromosomes are arranged at the equator. Each chromosome comprises of two sister chromatids (produced due to DNA synthesis in the S phase) joined at the centromere. In the anaphase stage, the centromere splits and the two sister chromatids move to opposite poles.
So, the correct answer is option C.
How many chromosomes will be in cells of human, produced by meiosis?
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46
0%
69
0%
23
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100
Explanation
23 chromosomes are present in the human cell during meiosis. A typical diploid human cell contains 23 pairs of chromosomes; 46 total, half of maternal origin and half of paternal origin. Meiosis produces haploid gametes with one set of 23 chromosomes. When two gametes fuse, the resulting zygote is once again diploid, with the mother and father each contributing 23 chromosomes.
What will happen if you are provided with root-tips of onion in your class and are asked to count the chromosomes, which of the following stage can be observed easily?
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Telophase
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Anaphase
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Prophase
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Metaphase
Explanation
Onion root tips are used to study the stages of cell division as, root tip contains highly dividing cells. Metaphase chromosome is a chromosome in the stage of the cell cycle (the sequence of events in the life of a cell) when a chromosome is most condensed and easiest to distinguish and so to study. Metaphase chromosomes are often chosen for karyotyping and for chromosome analysis because they are readily seen.
So, the correct answer is option D.
Amitosis was coined by
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Farmer
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Remac
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Strassburger
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A. Flemming
Explanation
Amitosis is a term describing cell division without nuclear envelope breakdown and formation of the well-visible mitotic spindle and condensed chromosomes. It is the direct cell division. It is also called as closed mitosis. The term amitosis was coined by Remac.
So, the correct answer is option B.
DNA duplication occurs at which of the following stage?
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Meiosis II
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Mitotic interphase
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Mitosis only
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Both, meiosis and mitosis
Explanation
DNA duplication occurs at mitosis and meiosis both. In mitotic cell division, the amount of DNA in the daughter cells will be equal to the parent cell and DNA will be double of the parent cell. In general, karyokinesis that is the division of the nucleus is followed by cytokinesis, which divides the cytoplasm, organelles, and cell membrane into two new cells containing roughly equal shares of these cellular components. Mitosis is the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell. While in meiosis the DNA of each chromosome is replicated so that it consists of two identical sister chromatids.
So, the correct answer is option D.
In which of the following stages the chromosomes appear as beaded structures?
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Leptotene
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Pachytene
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Diakinesis
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Telophase I
Explanation
Prophase I is the longest stage of meiosis I. The chromosomes appear as beaded structures at leptotene stage. It is the first stage of meiosis I
So, the correct answer is option A.
Nucleolar organizer is a
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Primary constriction
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Secondary constriction
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Tertiary constriction
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Centriole
Explanation
The nucleolus organizer region (NOR) or nucleolar organizer is a chromosomal region around which the nucleolus forms. This region is the particular part of a chromosome that is associated with a nucleolus after the nucleus divides. Nucleolus organizer regions are head-to-tail arrays of genes encoding the precursor of the three largest ribosomal RNAs. NORs include active rRNA genes, which give rise to secondary constrictions of metaphase chromosomes, and silent rRNA genes, which are often highly compacted in dense heterochromatin. At metaphase, a proteinaceous remnant of the nucleolus often remains associated with the secondary constriction. So, the nucleolar organizer is a secondary construction and not primary or tertiary construction and centriole.
So, the correct answer is option B.
Division of nucleus is indirect in
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Mitosis
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Binary fission
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Budding
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Fragmentation
Explanation
Mitosis is known as equational division. it mainly occurs in somatic cells. The stages of mitosis are prophase, metaphase, anaphase, and telophase. During mitosis, the chromosomes, which have already duplicated, condense and attach to fibers that pull one copy of each chromosome to opposite sides of the cell. The cell, then, divides by cytokinesis to produce two genetically identical daughter cells.
So, the correct answer is option A.
Cell cycle was divided into four stages i.e. G$$_1$$, S, G$$_2$$, M by
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W. Flemming
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Strass burger
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Howard and Pelc
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Farmer
Explanation
Howard and Pelc divided cell cycle in four stage. The cell cycle is an ordered set of events, culminating in cell growth and division into two daughter cells. Non-dividing cells not considered to be in the cell cycle. The stages are G$$_1$$-S-G$$_2$$-M. The G$$_1$$ stage stands for "GAP 1". The S stage stands for "Synthesis". This is the stage when DNA replication occurs. The G$$_2$$ stage stands for "GAP 2". The M stage stands for "mitosis", and is when and cytoplasmic division occur.
In which stage of cell division, division of matrix of chromosome occurs?
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Late prophase
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Early metaphase
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Late metaphase
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Anaphase
Explanation
During late metaphase, a chromosome consists of two chromatids joined together by the centromere, and get arranged at the equatorial plate. The spindle fibres contract, separating each chromosome into its two chromatids, or "single" chromosomes. One of each pair of chromatids goes to each of the two new cells that form. So, if the cell had four double chromosomes before metaphase, the new cells will each have four single chromosomes. The number of chromosomes remains unchanged, the double chromosomes have simply become single chromosomes.
So, the correct answer is option C.
Mitosis term was coined by
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Flemming
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Watson
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Thomson
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Addison
Explanation
German zoologist Otto Btschli was one of the first researchers who might have claimed the discovery of the process presently known as "mitosis", a term coined by Walther Flemming in 1882. Mitosis was discovered in frog, rabbit, and cat corneal cells in 1873 and described for the first time by the Polish histologist Wacaw Mayzel in 1875.
Which division maintains genetic similarity?
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Mitosis
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Meiosis
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Amitosis
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Reduction division
Explanation
Mitosis maintains genetic similarity. The process of mitosis is fast and highly complex. During mitosis, the chromosomes, which have already duplicated, condense and attach to fibers that pull one copy of each chromosome to opposite sides of the cell. The cell then divides by cytokinesis to produce two genetically identical daughter cells.
So, the correct answer is option A.
The nuclear envelope reappears at which of the following phase?
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Metaphase
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Prophase
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Anaphase
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Telophase
Explanation
The nuclear envelope reappears at telophase. During telophase, the effects of prophase and prometaphase are that the nuclear membrane and nucleolus disintegrating are reversed. Two daughter nuclei form in each daughter cell.
So, the correct answer is option D.
Number of meiosis required to produce 100 megaspore in angiosperms are
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125
0%
100
0%
25
0%
75
Explanation
A megaspore mother cell or megasporocyte is a diploid cell in plants in which meiosis will occur, resulting in the production of four megaspores. Generally, within each sporangium, meiosis of a megaspore mother cell produced four haploid megaspores, In gymnosperms and angiosperms, only one of these four megaspores is functional at maturity and the other three degenerate. So, one megaspore mother cell upon meiosis gives one viable megaspore.
So, the correct answer is option B
Which of the two events together restore the normal number of chromosomes in life cycle?
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Mitosis and Meiosis
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Meiosis and fertilisation
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Fertilisation and mitosis
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Only meiosis
Explanation
Meiosis and fertilization restore the normal number of chromosomes in the life cycle. Meiosis produces haploid gametes with one set of 23 chromosomes. When two gametes fuse, the resulting zygote is once again diploid, with the mother and father each contributing 23 chromosomes.
So, the correct answer is option B.
The slipping of chiasmata towards the ends of bivalents called as
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Terminalisation
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Diakinesis
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Interkinesis
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Heteropycnosis
Explanation
The slipping of chiasmata towards the ends of bivalents is called as terminalisation. They separate along with the cell. The chiasmata are thought to be the points where two non-sister chromatids exchange genetic material during chromosomal crossover during meiosis (sister chromatids also form chiasmata between each other, but because their genetic material is identical, it does not cause any change in the resulting daughter cells). The chiasmata become visible during the diplotene stage of prophase I of meiosis I, but the actual "crossing-over" of genetic material is thought to occur during the previous pachytene stage. When tetrads, which are composed of two pairs of sister chromatids, begin to split the only points of contact are at the chiasmata.
So, the correct answer is option A.
The chromosomes are bivalent in
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Prophase and metaphase
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Anaphase and telophase
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Prophase and telophase
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Metaphase and anaphase
Explanation
The DNA replication takes place in the S-phase of interphase. The replicated DNA is present in the form of sister chromatids attached to the centromere of the same chromosome. The condensation of the chromosomes take place in the prophase and the homologous chromosomes get aligned together to form the bivalent. These structures are present in the prophase and metaphase. In the anaphase, they get separated by migrating towards the opposite poles.
Thus, the correct answer is option A.
In animals, active mitosis can be observed
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At the base of nails
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At the apex of hairs
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Dermis of skin
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Glans
Explanation
Mitosis is a part of cell cycle process by which the chromosomes in a cell nucleus are separated into two identical sets of chromosomes. It is an equational cell division. Cells of bone marrow, the base of nails and skin (hypodermis) are commonly used to observe mitosis in animal cells.
So, the correct answer is option A.
Match the column I with column II and select the correct answer.
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A-i, B-ii, C-iii, D-iv, E-v
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A-iv, B-v, C-ii, D-i, E-iii
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A-iii, B-iv, C-v, D-ii, E-i
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A-ii, B-iii, C-iv, D-i, E-v
Explanation
1. The pachytene - At this point a tetrad of the chromosomes has formed known as a bivalent. This is the stage when chromosomal crossover (crossing over) occurs. Non-sister chromatids of homologous chromosomes may exchange segments over regions of homology.
2. The zygotene stage - occurs as the chromosomes approximately line up with each other into homologous chromosome pairs. In some organisms, this is called as the bouquet stage because of the way the telomeres cluster at one end of the nucleus. At this stage, the synapsis of homologous chromosomes takes place, facilitated by assembly of central element of the synaptonemal complex.
3. During the diplotene stage, the synaptonemal complex degrades and homologous chromosomes separate from one another a little. The chromosomes themselves uncoil a bit, allowing some transcription of DNA. However, the homologous chromosomes of each bivalent remain tightly bound at chiasmata, the regions where crossing-over occurred.
4. The first stage of prophase I is the leptotene stage. In this stage of prophase I, individual chromosomes each consisting of two sister chromatids condense from the diffuse interphase conformation into visible strands within the nucleus. However, the two sister chromatids are still so tightly bound that they are indistinguishable from one another.
5. During leptotene, lateral elements of the synaptonemal complex assemble.
6. Chromosomes condense further during the diakinesis stage. This is the first point in meiosis where the four parts of the tetrads are actually visible. Sites of crossing over entangle together, effectively overlapping, making chiasmata clearly visible. During this stage terminalization occurs.
Thus, option B is correct.
The division of nucleus is indirect in
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Mitosis
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Meiosis
0%
Amitosis
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Both A and B
Explanation
The division of nucleus is indirect in both mitosis and meiosis. Cell division is the process by which a parent cell divides into two or more daughter cells. There are two distinct types of cell division they are a vegetative division, which produces each daughter cell which is genetically identical to the parent cell (mitosis), and a reductive cell division, where the number of chromosomes in the daughter cells is reduced by half, to produce haploid gametes (meiosis).
Amitosis involves the direct division of nucleus without the spindle fiber formation.
So, the correct answer is option D.
Duplication of chromosomes without the division of nucleus is called as
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Cytokinesis
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Plasmotomy
0%
Endomitosis
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Dinomitosis
Explanation
Endomitosis involves the duplication of chromosomes without the division of nucleus. Endoreplication or endomitosis is a replication of the nuclear genome in the absence of cell division, which leads to elevated nuclear gene content and polyploidy. Endoreplication can be understood simply as a variant form of the mitotic cell cycle (G$$_1$$-S-G$$_2$$-M) in which mitosis is aborted prior to cytokinesis or circumvented entirely, due in part to modulation of cyclin-dependent kinase (CDK) activity.
So, the correct answer is option C.
The colchicine, a mitotic poison, arrests the cell division in which of the following phase?
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G$$_1$$ phase
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G$$_2$$ phase
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Anaphase
0%
Metaphase
Explanation
Colchicine is a mitotic inhibitor. A mitotic inhibitor is a drug that inhibits mitosis or cell division.
Colchicine prevents spindle formation which occurs during the metaphase stage of cell division.
So, the correct answer is option D.
A contractile mid-body forms during cytokinesis in
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Animal
0%
Higher plants
0%
Fungi
0%
Algae
Explanation
A contractile midbody forms during cytokinesis in animals. A contractile ring, made of non-muscle myosin II and actin filaments, assembles equatorially at the cell cortex. Myosin II uses the free energy released when ATP is hydrolyzed to move along these actin filaments, constricting the cell membrane to form a cleavage furrow. Continued hydrolysis causes this cleavage furrow to ingress.
So, the correct answer is option A.
The chromosome exhibit high level of coiling at which phase of karyokinesis?
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Prophase
0%
Metaphase
0%
Telophase
0%
Interphase
Explanation
Chromosome exhibits a high level of coiling at metaphase. Metaphase is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their 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.
So, the correct answer is option B.
The cellular structure which disappear during mitosis is
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Plasma membrane
0%
Nuclear membrane
0%
Mitochondria
0%
Nuclear membrane and nucleolus
Explanation
The cellular structure that disappears during mitosis is nuclear membrane and nucleolus.
Mitosis
maintains genetic similarity. The sequence of events is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During mitosis, the chromosomes, which have already duplicated, condense and attach to fibers that pull one copy of each chromosome to opposite sides of the cell. The cell then divides by cytokinesis to produce two genetically identical daughter cells.
So, the correct answer is 'Nuclear membrane and nucleolus'.
During cell division, chromosome move towards different poles due to
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Centriole
0%
Vacuole formation
0%
Microtubules
0%
Cytokinesis
Explanation
During cell division chromosome move towards different poles due to microtubules. Microtubules are found at kinetochores and used to pull chromatids apart during mitosis. In polarized interphase cells, microtubules are disproportionately oriented from the MTOC toward the site of polarity, such as the leading edge of migrating fibroblasts.
So, the correct answer is option C.
The spindle fibers which extend from pole to kinetochores are
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0%
Chromosomal or tractile
0%
Interzonal fibers
0%
Continuous fibers
0%
Astral rays
Explanation
The spindle fibres that are continuous from one pole to another pole of the cell are termed as continuous fibres while those extending from centromere of the chromosome to the pole are called as chromosomal spindle fibres. The spindle fibres present between centromeres of separating chromatids is termed in interzonal fibres. Microtubules that spread out from the centrosome in the opposite direction from the spindle itself are collectively termed as astral rays.
So, the correct answer is option A.
The interzonal fibers occur in
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0%
Prophase
0%
Early metaphase
0%
Late prophase
0%
Anaphase
Explanation
In the last anaphase, the zone between the two sets of chromosomes or the equatorial region gradually increases.The movement (and separation) of the chromosome is controlled by spindle fibres, which stretch and form interzonal fibres. A band of ‘interzonal fibres’ is often seen for a time after the separation has been accomplished, connecting the chromosomes which have pulled apart and often including a remnant of the spindle.
So, the correct answer is 'D'.
Meiotic cell division is also termed as reduction division because of
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0%
Involvement of gametes
0%
Doubling of chromosomes
0%
Elimination of chromosomes
0%
Number of chromosomes becomes halved
Explanation
D. Number of chromosomes becomes halved
EXPLANATION: The cellular division in meiosis I is called the reduction division because it results in the reduction of the chromosome number. The chromosome number becomes haploid from diploid.
The meiosis takes place in
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Apical meristem
0%
Inter calary meristem
0%
Reproductive cells
0%
Vegetative cells
Explanation
Meiosis takes place in reproductive cells. Meiosis results in four haploid daughter cells by undergoing one round of DNA replication followed by two divisions: homologous chromosomes are separated in the first division, and sister chromatids are separated in the second division. Meiosis produces haploid gametes with one set of 23 chromosomes. When two gametes fuse, the resulting zygote is once again diploid.
So, the correct answer is option C.
The most fastest stage of cell division is
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0%
Leptotene
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Zygotene
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Pachytene
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Diplotene
In which stage of cell division, number of chromosomes is best counted?
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Prophase
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Metaphase
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Telophase
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Interphase
Explanation
The number of chromosomes is best counted during metaphase. In metaphase, the centromeres of the chromosomes convene themselves on the metaphase plate an imaginary line that is equidistant from the two centrosome poles. This even alignment is due to the counterbalance of the pulling powers generated by the opposing kinetochore microtubules, analogous to a tug-of-war between two people of equal strength.
So, the correct answer is option B.
In which of the following division of centromere occurs?
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Late prophase or early metaphase
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Late metaphase or early anaphase
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Late anaphase or early telophase
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Late telophase
Explanation
Division of centromere occurs in late metaphase or early anaphase.
During late metaphase, a chromosome consists of two chromatids, joined together by the centromere, which is further separated during the anaphase due to contraction and relaxation of spindle fibers.
So, the correct answer is option B.
Genetic information is transferred from zygote to all body cell by
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Meiosis
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Amitosis
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Endomitosis
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Mitosis
Explanation
Genetic information is transferred from zygote to all body cell by mitosis. The process of mitosis is fast and highly complex. The sequence of events is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During mitosis, the chromosomes, which have already duplicated, condense and attach to fibers that pull one copy of each chromosome to opposite sides of the cell. The cell then divides by cytokinesis to produce two genetically identical daughter cells.
So, the correct answer is option D.
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Practice Class 11 Medical Biology Quiz Questions and Answers
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