Tag: nucleus and chromosome

Questions Related to nucleus and chromosome

Chromosome end is called

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

  1. Telomere

  2. Centromere

  3. Satellite

  4. Metamere

Show answer
Correct Option: A
Explanation:
  • A telomere is the end portion of a chromosome.
  • It is a region of repetitive nucleotide sequences present at each end of a chromosome that helps the chromosome from deterioration or fusion with other chromosomes. 
  • So, the correct answer is 'Telomere'.

Parascaris possesses chromosome

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

  1. Monocentric

  2. Dicentric

  3. Polycentric

  4. Holocentric

Show answer
Correct Option: C
Explanation:

Parascaris, first studied by Boveri (1887), has polycentric chromosomes, each of which consists of six segments, each segment having one centrally located centromere. So, the correct answer is option C.

Read the given statements
(i) Centromere is present in the middle of the chromosome and forms two equal arms.
(ii) Chromosome has a terminal centromere
(iii) Centromere lies close to the end of the chromosome forming one extremely short and one very long arm
(iv) Centremere lies slightly away from the middle of the chromosome resulting into one shorter arm and one longer arm.
Select the correct option as per the codes given above-

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

  1. Meta centric- (i); Submeta centric- (iv); Acro centric- (iii); Telo centric- (ii)

  2. Meta centric- (i); Submeta centric- (ii); Acro centric- (iii); Telo centric- (iv)

  3. Meta centric- (iv); Submeta centric- (iv; Acro centric- (iii); Telo centric- (ii)

  4. Meta centric- (iv); Submeta centric- (ii); Acro centric- (iii); Telo centric- (i)

Show answer
Correct Option: A
Explanation:

Every chromosome has a primary constriction or the centromere on the sides of which kinetochores are present. Based on the position of centromere, the chromosomes are of 4 types:

  • Metacentric -  Centromere is present in the middle of the chromosome and forms two equal arms.
  • Submetacentric -  Centromere lies slightly away from the middle of the chromosome resulting into one shorter arm and one longer arm.
  • Acrocentric - Centromere lies close to the end of the chromosome forming one extremely short and one very long arm. 
  • Telocentric - Chromosome has a terminal centromere. 
  • So, the correct option is 'Option A' .

When stained with a certain dye, the chromosomes show alternate light and dark bands known as Q-bands under the microscope. Name the dye.

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

  1. Fluorescent dyes

  2. Haematoxylin

  3. Giemsa stain

  4. Quinacrine mustard

Show answer
Correct Option: D
Explanation:

Q band is a typical pattern which is obtained by using Quinacrine mustard dye. Nucleus located in the centre of each cell has chromosomes coiled in the form of chromatin network. Chromosomes are gene carriers. They are made up of 2 chromatids, that are joined to each other through a centromere. 

heterochromatic DNA which is firmly packed and coiled is commonly stained by this dye. The pattern is similar to that obtained by light and dark bands obtained by G banding. The regions having rich Adenine Thymine complexes are highlighted with yellow fluorescence as seen in Q banding.
So the correct answer is " Quinacrine mustard ".

Synaptinemal complex was first described by

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

  1. Moses

  2. Bowmann

  3. Montgomery

  4. Pfitzner

Show answer
Correct Option: A
Explanation:

The snaptinemal complex was first described by Montrose J. Moses and D. Fawcett in 1956. Moses discovered in primary spermatocyte of crayfish and Fawcett discovered in spermatocytes of pigeon, cat, and man etc. It is protein structure that forms between homologous chromosomes during meiosis and mediates chromosome pairing.
So the correct option is A

Match column I with column II and select the correct option from the given codes

Sr.no  List I   Sr.no  List II
 a.  V-shaped at anaphase  1.  Acrocentric chromosome
 b.  L-shaped at anaphase   2.  Metacentric chromosome
 c.  J-shaped at anaphase  3.  Telocentric chromosome
 d.  I- shaped at anaphase  4.  Sub-metacentric chromosome

.

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

  1. A-(iv),B-(ii),C-(i),D-(iii)

  2. A-(ii),B-(iv),C-(i),D-(iii)

  3. A-(ii),B-(iv),C-(iii),D-(i)

  4. A-(iv),B-(iii),C-(ii),D-(i)

Show answer
Correct Option: B
Explanation:

Anaphase is a stage where the chromosomes split from the middle and two chromatin get separate and both the chromatids move toward opposite poles due to a repulsive force which is known as an aphasic moment.

The different shapes of chromosome become evident during chromosome movement that is metacentric, acrocentric et cetera. If the chromosome is V-shaped at anaphase then it would be metacentric because it is from the exact centre of the centromere.
 If it is L shaped at anaphase then it will be submetacentric because one arm would be smaller than the other arm. If it is J shaped then it is acrocentric chromosome because it is on one end of the chromosome and if it is I shaped then it is telocentric
So, the correct option is 'A-(ii),B-(iv),C-(i),D-(iii)'

Cause of chromosome laggards in meiosis is?

botany nucleus and chromosome membrane bound organelles cell: size and differentiation microscopy

  1. Inversion

  2. Dicentric chromosome

  3. Acentric chromosome

  4. Duplication of a gene

Show answer
Correct Option: B
Explanation:
A laggard is defined as a chromosome that does not overlap along the long axis of the spindle with any of the properly segregating chromosomes. A dicentric chromosome is an abnormal chromosome with two centromeres. It is formed through the fusion of two chromosome segments, each with a centromere, resulting in the loss of acentric fragments (lacking a centromere) and the formation of dicentric fragments.

So, the correct answer is 'Dicentric chromosome'.

What are the spindle fibres that connect the centromere of chromosome to the respective poles called?

botany nucleus and chromosome membrane bound organelles cell: size and differentiation microscopy

  1. Astral rays

  2. Interpolar fibres

  3. Chromosomal fibres

  4. Inter chromosomal fibres

Show answer
Correct Option: C
Explanation:
The central region of the chromosome where the two arms of chromatid are attached is called as the centromere. It is the region where the spindle fibers attach at the time of the cell division and are called as chromosomal fibers. 
Thus the correct answer is option C. 

Spindle chromosomes have

botany nucleus and chromosome membrane bound organelles cell: size and differentiation microscopy

  1. Centriole

  2. Kinetochore

  3. Chromocentre

  4. Chromomere

Show answer
Correct Option: B
Explanation:

Chromosomes when attached to spindle fibres are called as spindle chromosomes. These Chromosomes have narrow very lightly coloured centromere or primary constriction. The centromere has a proteinaceous covering called as kinetochore on the two free surface of the centromere complex. The kinetochore has centromere binding proteins.

Centromere is required for -

botany nucleus and chromosome membrane bound organelles cell: size and differentiation microscopy

  1. Movement of chromosomes towards poles

  2. Cytoplasmic cleavage

  3. Crossing over

  4. Transcription

Show answer
Correct Option: A
Explanation:

Centromere is present in every cell. It is a specific DNA sequence in a chromosome. It is specifically useful in the process of cell division. During mitosis, the spindle fibres attach to the centromeres via kinetochore and all the chromosomes are arranged in an equatoral plane. After this, the chromosomes move towards their respective poles and cell division takes place.

So, option A is the correct answer.