List of top Biology Questions

Explain the amplification of gene of interest using the technique of Polymerase Chain Reaction (PCR).
Enlist one advantage and two disadvantages of Green Revolution.
Explain the biological treatment of primary effluent when passed into the large aeration tanks in a sewage treatment plant (STP).

Study the given below single strand of deoxyribonucleic acid depicted in the form of a “stick” diagram with 5′ – 3′ end directionality, sugars as vertical lines and bases as single letter abbreviations and answer the questions that follow.

Name the covalent bonds depicted as (a) and (b) in the form of slanting lines in the diagram.
How many purines are present in the given “stick” diagram?
Draw the chemical structure of the given polynucleotide chain of DNA.

According to a recent wildlife report, the biggest threat to the tiger's survival in Mudumalai Tiger Reserve (MTR) was found to be a small, beautiful flower, \textit{Lantana camara, a tropical American shrub, that invaded 40% of India's tiger range. Tamil Nadu department's Lantana weed eradication drive helped to restore the dying MTR thereby also reducing human-wildlife conflicts. MTR is home to 25 species of grasses and legumes.
Explain how did the removal of Lantana help in restoring the dying Mudumalai Tiger Reserve.
Why is the invasion of Lantana camara a cause of concern in MTR?
Explain the process of formation of placenta in a human female after the implantation of the blastocyst in the endometrium of the uterus.
Gregor Mendel conducted hybridisation experiments in garden pea for seven years and proposed the law of inheritance.
Why was he successful in his hybridisation experiments? Give two reasons.
State the law of independent assortment as proposed by Mendel after his dihybrid crosses.
Correctly depict (also indicate the trophic level) and describe the ecological pyramid of biomass in sea with 40 standing crop of phytoplankton supporting 90 standing crop of zooplankton which further supports 120 small fishes.
Explain how the interaction between sea anemone and clownfish is one of the best examples of commensalism in nature.
Assertion (A): ABO blood grouping in humans is an example of multiple allelism.
Reason (R): More than two genes in a population govern the same character in ABO blood grouping in humans.

Assume that the given mRNA (start site is not depicted) is theoretically translated in two reading frames.
Translation starting from the first nucleotide (Reading frame 1)
Translation starting from the second nucleotide (Reading frame 2)

Frame 1: 5'--CUCGCUUUGCCGAUCAAGGGUUA--3'
Frame 2: 5'--GUGGCACUCAGUCCUUAAUGGCG--3'

Answer the following question: How many amino acids will be specified in case (a) and case (b) on translation? Justify your answer.

(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?
Assertion (A): ‘Saheli’, an oral contraceptive inhibits ovulation and increases phagocytosis of sperms.
Reason (R): It is a non-steroidal preparation.
Assertion (A): A person infected with malaria suffers from chill and high fever, recurring every three or four days.
Reason (R): The parasite attacks the RBC resulting in their rupture and release of haemozoin.
The correct depiction of the experiment performed by Matthew Meselson and Franklin Stahl to prove that DNA replicates semi-conservatively on separation of DNA by centrifugation after 40 minutes is:
In a pea plant (Pisum sativum) inflated pod shape is dominant over constricted pod shape. The expected ratio of phenotypes of the offspring in a cross between both the parents with heterozygous inflated pod shape will be:
Bioactive molecule Cyclosporin A used for human welfare is derived from:
The substrate used during DNA replication by the enzyme DNA-dependent DNA polymerase 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 TAC.
 

In the given pedigree chart, a cross between a normal couple resulted in a son who was haemophilic and a normal daughter. In course of time, when the daughter was married to a normal man, to their surprise the grandson was also haemophilic.

Choose the option that indicates the correct inheritance of trait in the above pedigree chart:

About 15 mya during human evolution, the primates which used to walk like gorillas and chimpanzees were:
In which of the following human diseases does the body's self-defence mechanism attack self-cells?
Given below are a few statements with reference to the accessory ducts of the human male reproductive system:
  • [(i)] The seminiferous tubules of the testes open into rete testis then into the vas deferens.
  • [(ii)] The vasa efferentia leave the testes and open into the epididymis.
  • [(iii)] The epididymis leads to vas deferens that ascends into the abdomen.
  • [(iv)] The vas deferens receives a duct from the prostrate gland and opens into the urethra as ejaculatory duct.
  • [(v)] The urethra originates from the urinary bladder and extends through the penis to its external opening, urethral meatus.
Choose the option with all true statements from the given options:
Select the statements that are true for a typical dicotyledonous embryo from the given options.
In its extended 'beads-on-string' form of chromatin, the 'beads' in the string represent: