Tag: the mitotic cell cycle

Questions Related to the mitotic cell cycle

Who hypothesised that individuals of the same species have the same number of chromosomes?

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. Augustus Weisemann

  2. Theodor Boveri

  3. Wilhelm Roux

  4. Robert Remark

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Correct Option: A

Sometimes a few chromosomes have non staining secondary constriction at a constant location. This gives the appearance of a small fragment, called : 

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. NOR

  2. Satellite

  3. Telomere

  4. kinetochore

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Correct Option: A

Which of the following statements is incorrect?

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. Every chromosomes essentially has a secondary constriction

  2. The interphase nucleus has a loose and indistinct network of nucleoprotein fibres called chromatin

  3. A single human cell has approximately $2.2$ metre long thread of DNA distributed among its forty six chromosomes

  4. Chromatin contains DNA and some basic proteins called histone, some non histone proteins and also RNA

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Correct Option: A

What would be the number of chromosomes of the aleurone cells of a plant with $42$ chromosomes in its root tip cells?

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. $21$

  2. $42$

  3. $63$

  4. $84$

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Correct Option: A

Chromosome consists of

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. DNA only

  2. DNA and histone protein

  3. DNA, histone proteins and non-histones proteins

  4. DNA and non-histones protein

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Correct Option: C
Explanation:

Chromosomes are made up of DNA and protein. Histone and non-histones proteins are associated with chromosomal DNA. Histone participate as structural components and provide strength and stability and protect DNA from shearing and breakage while the non-histones act as functional or regulatory components either in activation or repression of genes.

So, the correct answer is option C.

The first person to observe chromosome was

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. Waldayer

  2. Hofmeister

  3. F. Meischer

  4. G. Cuvier

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Correct Option: B
Explanation:

Chromosomes were discovered by Hofmeister (1848), studied by Strasburger (1875) and given the present name by Waldeyer (1888) after their staining by dyes like Janus Green. Chromosomes are a thread like structure. It is composed of DNA and protein and it is considered as a carrier of genetic characters from parents to offspring.

So, the correct answer is option B.

Chromosomes are composed of

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. DNA, RNA, histones, non-histones

  2. DNA and histones

  3. DNA and RNA

  4. DNA, RNA and histones

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Correct Option: A
Explanation:

Chromosomes are composed of DNA, RNA, histones, non-histones. A chromosome is a packaged and organized chromatin, a complex of macromolecules found in cells, consisting of DNA and protein. The functional segments of DNA are known as genes. The DNA-bound macromolecules are proteins, which serve to package the DNA and control its functions.

So, the correct answer is option A.

The non-sticky chromosomal ends are known as

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. Chromatids

  2. Centromere

  3. Chromomere

  4. Telomere

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Correct Option: D
Explanation:

The telomeres do not have any overhanging ends of nucleotides so it is known as non sticky chromosome ends called telomere. A telomere is a region of repetitive nucleotide sequences at each end of a chromatid, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. 

So, the correct answer is option D.

Chromonemata are embedded in a

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. Stroma

  2. Matrix

  3. Sugar

  4. Mucilage

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Correct Option: B
Explanation:

Chromonemata are embedded in the matrix. Chromonemata are the spirally coiled central filament of a chromatid along which the chromomeres are aligned. A chromomere is one of the serially aligned beads or granules of a eukaryotic chromosome, resulting from local coiling of a continuous DNA thread. It is visible on a chromosome during the prophase of meiosis and mitosis. 

So, the correct answer is option B.

Bead like structure found on chromosome are called as

botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

  1. Chromomeres

  2. Chromonemata

  3. Chromonema

  4. Centriole

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Correct Option: A
Explanation:

A chromomere  is one of the serially aligned beads or granules of a eukaryotic chromosome, resulting from local coiling of a continuous DNA thread. It is visible on a chromosome during the prophase of meiosis and mitosis. The chromomeres are present during leptotene phase of prophase I during meiosis. During zygotene phase of prophase I, the chromomeres of homologs align with each other to form a homologous rough pairing. These chromomeres help provide a unique identity for each homologous pairs.

So, the correct answer is option A.