Tag: biology

Questions Related to biology

In human beings, the statistical probability of getting either a male or a female child is 50:50. Which of the following is the cause behind it?

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. The sex of an infant is determined by the type of sex chromosome contributed by the male gamete.

  2. The ratio of male gametes containing X chromosome and those containing Y chromosome is 50:50.

  3. Both A and B.

  4. None of these

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Correct Option: C
Explanation:
  • The sex of an infant is determined by the type of sex chromosome contributed by the male gamete. A male produces two types of sperms, one type bears 22+X composition and the other, 22+Y. Therefore, a male has 50% sperms with X chromosomes and the other 50% with Y chromosomes.
Anyone of the two types of the sperms can fertilize the egg. If a Y bearing sperm fertilizes the egg, the zygote will be a male (XY) and when X bearing sperm fertilizes the egg, the resulting zygote will be female (XX). Since the ratio of the X chromosome and the Y chromosome in a male gamete is 50:50. The statistical probability of male or female infants is also 50:50.

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

Which of the following statements is incorrect regarding lysozyme present in saliva?

biology structure and functions of living organisms -ii dental care, eye care and hair care dental care and dental diseases salivary glands

  1. It acts is an antibacterial agent.

  2. It prevents infections.

  3. It acts as an enzyme.

  4. All of these

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Correct Option: C
Explanation:

The correct answer is (c).

The salivary glands produce saliva. What is the function of saliva?

biology structure and functions of living organisms -ii dental care, eye care and hair care dental care and dental diseases salivary glands

  1. Digestion of food

  2. Purification of blood

  3. Keeping our body cool

  4. None of these

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Correct Option: A
Explanation:
  • Saliva is a thick, colourless and glistening liquid with about 98 per cent water in our mouth. The saliva contains chemicals like the mucus, salts, antibacterial substances and enzymes which help in the digestion of food especially starch.
  • The digestion of starch into a sugar called the maltose is done because of an enzyme, salivary amylase that the saliva contains. 

Silk is the product of

biology structure and functions of living organisms -ii dental care, eye care and hair care dental care and dental diseases salivary glands

  1. Salivary gland of the larva

  2. Cuticle of the adult

  3. Cuticle of the larva

  4. Salivary gland of the adult

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Correct Option: A
Explanation:

Among other visceral organs larva contains well- developed paired glands called silk glands. Silk is the secretion of salivary gland.