List of top Biology Questions asked in ICSE Class XII

Roselin had an aquarium at her home with 10 fish in it. In a year, a fish gave birth to 7 fish. During this period, 3 adult fish had died. Roselin's father purchased 2 more pairs of fish from market for the aquarium. Later, Roselin gifted 4 fish from the aquarium to her friend. Find out the growth rate of fish in Roselin's aquarium.

The amount of energy at the fourth trophic level in the food chain: Grass \(\rightarrow\) Zebra \(\rightarrow\) Crocodile \(\rightarrow\) Vulture is 4 J. What will be the amount of energy available at the sunlight and transducer level?

In a group discussion on pollination, Shubham argued that Cleistogamy was a type of Xenogamy whereas Ameena was of the opinion that it was a kind of Autogamy. Whose argument is correct? Justify.

Give a reason for the following: In HIV infected persons, the immune system is compromised.

Give a reason for the following: Kanika was suffering from SCID and needed periodic infusion of transformed lymphocytes.

Name the chemical messenger that activates Natural Killer T-cells and macrophages.

The enzyme polynucleotide phosphorylase helps the in-vitro synthesis of RNA. Name the scientist who discovered this enzyme.

Expand the abbreviation IUI.

Name the autoimmune disorder that affects the skeletal muscles in humans.

In a garden pea plant, the flowers are in axial (A) position. Find out the proportion of flowers in terminal position (a), if a cross is made between two heterozygous plants.

Given below are two statements marked Assertion and Reason.
Assertion: RNAi technique is applied to plants and animals to protect them from pest infestation.
Reason: This technique inhibits the expression of certain genes in pests.

The left hind limb of a person was swollen like elephant’s limb. Which one of the following was MOST likely the cause of swelling?

Choose the components that are required for the proper functioning of DNA polymerase enzyme.
(P) DNA template
(Q) A DNA primer
(R) An RNA primer
(S) Four different dNTPs

In a particular plant with bilobed dithecous anther, there were 50 Pollen Mother Cells. Only 25% could develop their pollen tubes. Calculate the number of pollen grains that would proceed for fertilisation.

A farmer notices that the leaves of his cabbage plants are curling up because of heavy infestation of aphids. Suggest one ecofriendly method to control their spread in the cabbage plants.

There were 770 frogs in a pond. 70 of them died within a month. Calculate the death rate of the population of frogs in the pond.

Meenu is suffering from a genetic disorder in which phenylpyruvic acid and its metabolites accumulate in blood. It causes impairment of nervous tissues. Which enzyme deficiency has caused this disorder in Meenu?

A scientist isolates a second restriction endonuclease from the strain DC3 of Helicobacter pyogenes. What would the scientist name it using the standard naming technique of restriction enzyme?

If the number of chromosomes in the cells of the calyx is 16, how many chromosomes will be formed in the endosperm after double fertilisation?

Zara is suffering from cough and has bluish lips. Her mucus is mixed with blood. What is the biological name of the causative organism responsible for Zara’s condition?

Explain the role of Restriction Endonucleases and Ligases in recombinant DNA technology.

Discuss the steps involved in Plant Breeding for developing disease-resistant varieties.

Explain the life cycle of Plasmodium (Malaria) and the role of the female Anopheles mosquito.