List of top Biology Questions

Which one of the following options shows the correct evolutionary order of the plants mentioned below?
(i) Ferns (ii) Ginkgo (iii) Zosterophyllum (iv) Gnetales
Choose the correct option.

If Meselson and Stahl's experiment is continued for 80 minutes (till III generation), what would be the ratio of DNA containing N$^{15}$/N$^{15}$ : N$^{15}$/N$^{14}$ : N$^{14}$/N$^{14}$ in the medium?

Study the items of Column-I and those of Column-II:
Column-I Column-II
(a) RNA polymerase I (i) 18s rRNA
(b) RNA polymerase II (ii) SnRNAs
(c) RNA polymerase III (iii) hnRNA
Choose the option that correctly matches the items of Column-I with those of Column-II:

Given below is a heterogeneous RNA formed during Eukaryotic transcription:

How many introns and exons respectively are present in the hnRNA?

The number of autosomes present in a human secondary spermatocyte

In a pedigree chart represents :

Given below is a diagram of T.S. of a monocot seed with parts I, II & III labelled :

Choose the option where parts I, II and III are identified correctly.

A child with blood group A has the father with blood group B and the mother with blood group AB. Choose the option that gives the correct genotypes of father, mother and the child :

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:

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?

Explain the process of formation of placenta in a human female after the implantation of the blastocyst in the endometrium of the uterus.

(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 separation and isolation of DNA fragments by a typical gel electrophoresis.

Select the statements that are true for outbreeding devices in the flowering plants.

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:

The first human-like hominid evolved during human evolution is supposed to be:

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.

The most widely used transgenic animal for testing the safety of vaccine before they are used in humans is:

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:

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’.

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: