Tag: natural selection

Questions Related to natural selection

Which one of the following traits of the parents cannot be inherited by their children?

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

  1. Cleft chin

  2. Snub nose

  3. Scarred eyebrow

  4. Brown eyes

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Correct Option: C
Explanation:

Scarred eyebrow is an acquired trait which is never passed on to the offspring because scarring does not change the genes of the reproductive cells of the parent.

Which of the following statements is correct?

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

  1. Accumulation of useful mutations through ages has led to the creation of new species of living beings.

  2. Genetic variability provides raw material for the operation of natural selection and reproductive isolation.

  3. Genetic variability is produced by gene mutations.

  4. All of the above.

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Correct Option: D
Explanation:

Genetic variability is the change in the sequence of the gens due to mutations. These mutations has led to new species generation. The so evolved species are selected in the environment based on natural selection

Laboratory mice are to be classified based on genes A, B, and C, none of  these are lethal genes. How many would be genetically different gametes if they are formed by genotype AaBbCc?

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

  1. $3$

  2. $6$

  3. $8$

  4. $9$

  5. $12$

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Correct Option: C

Ultimate source of variation is

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

  1. Fertilization

  2. Mitosis

  3. Meiosis

  4. Mutations

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Correct Option: D
Explanation:

Variation is a change or slight difference in condition, amount, or level, typically within certain limits appear in the progeny compared with parents. Variations appear in sexually reproducing organisms during meiosis and fertilization and also by mutations. So, the correct option is ‘Mutation’.

The ultimate source of continuous variations is 

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

  1. Natural selection

  2. Sexual reproduction

  3. Hormonal action

  4. Mutations

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Correct Option: B
Explanation:

Sexual reproduction involves gamete formation and fertilisation. During fertilisation, 1 gamete from each parent combines to form a zygote. Because of recombination and independent assortment in meiosis, each gamete contains a different set of DNA. This produces a unique combination of genes in the resulting zygote and ultimately within the organism.

As reproduction takes place continuously throughout the generation as well as these variations are inheritable, it is the ultimate source of continuous variations.
So, the correct option is 'Sexual reproduction.'

Which variations are temporary and are not connected with last or next generation?

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

  1. Hereditary variations

  2. Environmental variations

  3. Discontinuous variations

  4. Continuous variations

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Correct Option: B
Explanation:

In the living organisms, variation due to environment, not transmitted from generation to generation. so these are temporary, where as variations due to mutations are transmitted from generation to generation, so they are permanent. 

So, the correct option is 'Environmental variations'.

In introgressive hybridization, one species is completely replaced by another in nature.

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

  1. True

  2. False

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Correct Option: A
Explanation:
he movement of a gene (gene flow) from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species is called Introgressive hybridization.
So the given statement is true.

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

Show answer
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

Show answer
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.