Tag: botany

Quizzes (264) Questions (5276)

Questions Related to botany

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

Chemical composition of chromosome : 

  1. DNA and lipids

  2. DNA and carbohydrates

  3. Proteins and lipids

  4. DNA and proteins
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The chemical composition of a chromosome is DNA and proteins(histone). Because chromosome is a supercoiled structure made up by coiling of DNA on the proteins like histone

So the correct option is"DNA and Proteins".

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

Study of _________ helps in the determination of phylogeny and taxonomy.

  1. Chromosomes

  2. Cytoplasm

  3. Nucleoplasm

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

Chromosomes contain the genetic material that is conserved and modified over evolutionary time. By comparing chromosome structures and gene sequences, scientists can determine evolutionary relationships (phylogeny) and classify organisms (taxonomy).

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.