Tag: variation and its type

Questions Related to variation and its type

The most likely reason for the development of resistance against pesticides in insects damaging crops is:

botany classical genetics variation and its type natural selection introduction to genetics

  1. genetic recombination

  2. directed mutations

  3. acquired heritable changes

  4. none of these

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Correct Option: C
Explanation:
Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. Cases of resistance have been reported in all classes of pests (i.e. crop diseases, weeds, rodents, etc.), with 'crises' in insect control occurring early-on after the introduction of pesticide use in the 20th century. The Insecticide Resistance Action Committee (IRAC) definition of insecticide resistance is 'a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species'. Although the evolution of pesticide resistance is usually discussed as a result of pesticide use, it is important to keep in mind that pest populations can also adapt to non-chemical methods of control.
So the correct option is 'acquired heritable changes'.

Which of the following is not heritable?

biology variation variation and its type natural selection introduction to genetics

  1. Point mutation

  2. Chromosomal mutation

  3. Somatic mutation

  4. Gene mutation

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Correct Option: C
Explanation:

  • Point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a sequence of DNA or RNA. Each triplet codon corresponds to an amino acid when translated to protein. When one of these codons is changed by a point mutation, the corresponding amino acid of the protein is changed.
  • Chromosomal mutation is presence or absence of one or more set of chromosomes in a cell or a structural abnormality in the normal set of chromosomes.
  • Somatic mutation is the occurrence of a mutation in the somatic cells (cells other than sperm and egg) of the organism. These are frequently caused by environmental factors like exposure to UV rays or to certain chemicals. 
  • Gene mutation is a permanent alteration in the DNA sequence that makes up a gene. They are of two types: Hereditary mutations (inherited from parents) and Acquired mutation (occur at some time during a person's life).
So, the correct answer is 'Somatic mutation'

There is an inbuilt tendency to variation during reproduction, because of errors in DNA copying and as a result of sexual reproduction.

biology variation variation and its type natural selection introduction to genetics

  1. True

  2. False

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Correct Option: A
Explanation:

Sexual reproduction results in more variation than the asexual reproduction. During sexual reproduction, there are chances of errors occurring during DNA copying. Crossing over also takes place during sexual reproduction. All these ultimately result in the variation. This variation helps survival in species and also supports diversity in the course of evolution.

Thus, the correct answer is option A.

To be evolutionary successful, the mutation must occur in 

biology variation variation and its type natural selection introduction to genetics

  1. Somatoplasm

  2. Germplasm

  3. Karyolymph/zygote

  4. Ergastoplasm

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Correct Option: B
Explanation:

Total of specialized protoplasm other than germplasm in individual body or protoplasm of somatic cells is termed as somatoplasm. Germplasm is protoplasm of germ cells (egg and sperm cells) or any living tissues with the capability of generating new organisms. The germplasm is inherited from parents to offspring along with gametes; thus any mutation in germplasm is passed to progeny which is a requisite for successful mutation; option B is correct. Since somatoplasm is not passed to offspring, any mutation in it affects that individual only and is not passed to offspring which makes option A incorrect. The liquid phase of cell nucleus which harbours the nucleolus and chromatin and other structures is called as karyolymph. Similarly, the mutation in zygote affects single individual that develops from that zygote. Option C is incorrect. The granular endoplasmic reticulum that has studded ribosomes on its surface is called as ergastoplasm which is not inherited to offspring and thus is not suitable for successful mutation; option D is incorrect. Correct option B is correct. 

Which type of variation is inherited?

biology variation variation and its type natural selection introduction to genetics

  1. Somatic variation

  2. Germinal variation

  3. Both A and B

  4. None of the above

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Correct Option: B
Explanation:
The variation which affects the germinal or reproductive cells is called as germinal variation. It is heritable and genetically significant. It provides raw materials for evolution.

Which mutation/variation is not hereditary _____________.

biology variation variation and its type natural selection introduction to genetics

  1. Genetic

  2. Gametic

  3. Somatic

  4. Germinal.

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Correct Option: C
Explanation:

A sudden, inheritable, discontinuous variation due to change in chromosomes and genes is called Mutation. It is hereditary. Mutations in somatic cells are not hereditary.

So, the correct option is ‘somatic’.

Somaclonal variations can be obtained by

biology variation variation and its type natural selection introduction to genetics

  1. Application of colchicine

  2. Irradiation with $\gamma$-rays

  3. Tissue culture

  4. Hybridization

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Correct Option: C