List of top Biology Questions

Explain the process of separation and isolation of DNA fragments by a typical gel electrophoresis.
(a) (i) Give the full form of ‘ELISA’. Write the principle on which ELISA test is based.
(ii) Describe all the methods used to treat or cure Adenosine deaminase deficiency in humans.
Explain the process of formation of placenta in a human female after the implantation of the blastocyst in the endometrium of the uterus.
Thomas Hunt Morgan carried out several dihybrid crosses in Drosophila melanogaster to study genes that were sex linked. (a) Give four major reasons for using the tiny fruit flies by Morgan for his experiments. (b) How did Morgan and his group explain the physical association of the two genes on a chromosome to the frequency of recombination between gene pairs on the same chromosome?
Student to attempt either option (A) or (B):
(A) Write two features of an ideal contraceptive. Explain any one natural contraceptive method that makes the chances of conception almost nil.
(B) Explain GIFT and ICSI.
In a pea plant (Pisum sativum) green pod colour is dominant over yellow pod colour. The expected ratio of phenotypes of the first generation offspring in a cross between both the parents with heterozygous green pod colour will be:
The most widely used transgenic animal for testing the safety of vaccine before they are used in humans is:

Use the given information to select the amino acid attached to the 3′ end of tRNA during the process of translation, if the coding strand of the structural gene being transcribed has the nucleotide sequence ‘TCC’.

The first human-like hominid evolved during human evolution is supposed to be:
Select the statements that are true for outbreeding devices in the flowering plants.
    [(i)]
  • They discourage cross-pollination and ensure self-pollination.
  • They are advantageous as they lead to inbreeding depression.
  • Self-incompatibility prevents self-pollen from fertilising the ovules.
  • To prevent self-pollination in some species pollen release and stigma receptivity are not synchronised.
Choose the correct answer:
Allergy in humans is a result of release of the following chemicals from the mast cells:

A pedigree chart is shown below for a disease that is autosomal dominant. The genetic make-up of the first generation is:

Thalassemia and Sickle Cell Anaemia are both caused due to problem in globin molecule synthesis. Select the correct statement:

Given below are few statements with reference to oogenesis in a human female:

  • An unequal division of the primary oocyte forms a large secondary oocyte and a tiny first polar body.
  • A couple of thousands of oogonia are formed within each fetal ovary during embryonic development.
  • Primary oocytes start meiosis-I but it gets arrested temporarily at prophase-I during fetal development.
  • Fertilisation induces the completion of the meiotic division of the secondary oocyte.
  • A primary oocyte on meiosis forms an ovum and a polar body.

Choose the option with all true statements from the given options:

Answer either option-(A) or (B): (A)

  • Name the two genes encoding for the Bt toxin protein used in biotechnology for the control of cotton bollworms.
  • How does the expression of Bt toxin gene in Bt cotton plant help in providing resistance to cotton bollworms? Explain.

OR (B)

  • Explain the given methods of introducing the alien DNA in the host cells:
  • (I) Biolistics
  • (II) Microinjection
  • How is E. coli made 'competent' to take up a recombinant plasmid or DNA?

Thomas Hunt Morgan carried out several dihybrid crosses in Drosophila melanogaster to study genes that were sex linked.
(a) Give four major reasons for using the tiny fruit flies by Morgan for his experiments.
(b) How did Morgan and his group explain the physical association of the two genes on a chromosome to the frequency of recombination between gene pairs on the same chromosome?

Student to attempt either option (A) or (B):
(A) Write two features of an ideal contraceptive. Explain any one natural contraceptive method that makes the chances of conception almost nil. 
OR 
(B) Explain GIFT and ICSI.

Student to attempt either option (A) or (B):
(A) Explain how the immunity of a person is affected if there is atrophy (degeneration) of the thymus gland at an early stage of life. 
OR
(B) (i) What are interferons? Explain their role in providing immunity to a person. 
(ii) Which category of innate immunity defence barrier can interferons be classified into?

Large holes in 'Swiss cheese' are formed by the activity of microbes:
Early detection of HIV in suspected AIDS patients can be done using the diagnostic technique of:
The primates that probably lived in East Africa grasslands about two mya were:
Select the statements that are true for a typical megasporangium of flowering plants:
(i) It is attached to the placenta by hilum.
(ii) It has a chalaza end that represents the basal part of the ovule.
(iii) It has nucellus enclosed by integuments.
(iv) Its micropylar end is known as chalaza.
Choose the correct answer:
The type of antibodies produced during an immune response to allergens as dust and pollen grains in a person is:
A colourblind man marries a woman with normal sight who has no history of colourblindness in her family. What is the probability of their son being colourblind?
The simplest definition of a gene in eukaryotes is --- A unit of DNA that has information to mainly specify the synthesis of: