Tag: botany

Questions Related to botany

General length of chromosome is

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

  1. 5$\mu$m - 10$\mu$m

  2. 0.2$\mu$m - 2$\mu$m

  3. 0.1$\mu$m - 30$\mu$m

  4. 0.1$\mu$m - 4$\mu$m

Show answer
Correct Option: C
Explanation:

Chromosomes are the genetic material present in the nucleus of a cell. It is composed of DNA and protein. The functional segment of DNA is known as a gene. The size of chromosomes varies from as small as 0.1$\mu$m to as big as 15$\mu$m in length.

So, the correct answer is option C.

The chromosome that lacks a centromere is called as

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

  1. Telocentric

  2. Acentric

  3. Metacentric

  4. Acrocentric

Show answer
Correct Option: B
Explanation:
In acrocentric chromosome, the centromere is present close to the end of the chromosome. Due to this one arm is very short and another arm is longer. 
In metacentric, the centromere is in the middle of the chromosome and the two arms are of equal length. 
In telocentric, the centromere is present at the end of a chromosome.
In acentric the chromosome that lacks a centromere. So, the correct answer is option C.

The largest normal metaphasic chromosome has a size of

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

  1. $1\mu m$

  2. $10\mu m$

  3. $20\mu m$

  4. $30\mu m$

Show answer
Correct Option: D
Explanation:

The largest normal metaphasic chromosome has the size of 30nm with the base of the nucleosome core particle consists of the 146 base pairs of DNA. During metaphasic state, when a chromosome in its most condensed state can range in size between 130,000 base pairs in the endosymbiotic bacteria, then the chromatin can be further condensed by coiling into 30nm in fibres.
So, the correct answer is option D.

During staining, chromosomes get stained with

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

  1. Eosine

  2. Borax carmine

  3. Acetocarmine

  4. Safranin.

Show answer
Correct Option: C
Explanation:

  • Stains are used in the microscopic studies of different components and organelles within a cell.
A. Eosine is stain used to stain the cytoplasm of the cell because these acidic dyes bind to basic proteins in the cytoplasm of the cell.
B. Borax carmine consists of borax, carmine and water which produces a permanent red nuclear stain which stains the nucleus and the cytoplasm.
C. Acetocarmine is a saturated solution of carmine in 45% of acetic acid which is used for staining the unfixed chromosomes within the nucleus of a cell that is used to study different stages of the chromosomes in cell division.
D. Safranin is a basic counterstain dye used in histology and cytology.

So, the correct answer is 'Acetocarmine'.

The term chromonema was coined by

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

  1. Flemming

  2. Strasburger

  3. De Robertis

  4. Vijdovsky

Show answer
Correct Option: D
Explanation:

Chromonema is spirally coiled central filament that extends the entire length of a chromosome and on which the genes are located. During mitotic prophase, the chromosome material appeared as thin filaments which are known as chromonema. This term is introduced by Vijdovsky in 1912. 

It represents chromatids in the early stages of condensation. Hence option D is correct.

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