Tag: chromosome and its structure

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Questions Related to chromosome and its structure

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

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

  1. Augustus Weisemann

  2. Theodor Boveri

  3. Wilhelm Roux

  4. Robert Remark
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

August Weismann proposed the germ plasm theory and hypothesized that the number of chromosomes is constant for individuals of the same species, which is a fundamental concept in genetics.

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

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

  1. NOR

  2. Satellite

  3. Telomere

  4. kinetochore
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Certain chromosomes possess a secondary constriction at a constant specific location, which is non-staining and gives the appearance of a small chromosomal fragment separated from the main body. This distinct morphological feature is known as a satellite, and chromosomes possessing it are called satellite chromosomes.

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

Which of the following statements is incorrect?

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Not all chromosomes have a secondary constriction; only specific chromosomes (SAT-chromosomes) possess them. The other statements correctly describe chromatin, DNA length, and composition.

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

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

  1. $21$
  2. $42$
  3. $63$
  4. $84$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Root tip cells are diploid (2n), so 2n = 42, which means the haploid number n = 21. Aleurone cells in endosperm are triploid (3n) because they are formed by triple fusion. Therefore, the number of chromosomes in aleurone cells is 3 * 21 = 63.

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

Chromosome consists of

  1. DNA only

  2. DNA and histone protein

  3. DNA, histone proteins and non-histones proteins

  4. DNA and non-histones protein
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

The first person to observe chromosome was

  1. Waldayer

  2. Hofmeister

  3. F. Meischer

  4. G. Cuvier
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Chromosomes are composed of

  1. DNA, RNA, histones, non-histones

  2. DNA and histones

  3. DNA and RNA

  4. DNA, RNA and histones
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

The non-sticky chromosomal ends are known as

  1. Chromatids

  2. Centromere

  3. Chromomere

  4. Telomere
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

Chromonemata are embedded in a

  1. Stroma

  2. Matrix

  3. Sugar

  4. Mucilage
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Bead like structure found on chromosome are called as

  1. Chromomeres

  2. Chromonemata

  3. Chromonema

  4. Centriole
Reveal answer Fill a bubble to check yourself
A Correct answer
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.