Biology (Theory) Specimen Paper 2024-2025 ISC (Science) ISC Class 12 Question Paper Solution

What is the biological name of the causative agent of the disease Sapna is suffering from?

The number of chromosomes in the leaf cells of a male plant is 40 and in the stem cells of a female plant is 60. If they are artificially hybridised, what will be the number of chromosomes in the endosperm?

How many cycles of PCR are required to produce 250 molecules of DNA, starting with a single parental strand?

Which is the most commonly prescribed non-steroidal oral contraceptive pill in India?

Tall pea plants having green pods were crossed with dwarf pea plants having yellow pods. Out of 80 plants, how many are likely to be tall plants in the F₂ generation?

Write a 6-nucleotide long palindromic sequence on a double stranded DNA, which was reverse transcribed by the following nucleotide sequence on a retroviral RNA.

3’-GUA--- 5’

In the given figure of mammalian spermatozoon, “X” is an organelle. Identify the organelle.

Observe the relation between the first two words and then fill in the fourth word.

Histamine: Mast cells :: Antibody: ______.

Which of the following sequences of mRNA will NOT translate completely?

5'- AUG UUC AGC UCG UGA -3'

5'- AUG AAC UAA CCA CUC -3'

5'- AUG UUA CUC GCG UAA -3'

5'- AUG CCA UAC GAC UAG - 3'

Which one of the following choices reflects the correct number of chromosomes in the zygote and in the second polar body of Drosophila melanogaster?

I

II

III

IV

Assertion: Earthworm is called a detritivore.

Reason: It breaks down the water-soluble inorganic nutrients, which percolate down into the soil.

Both Assertion and Reason are true and Reason is the correct explanation for Assertion.

Both Assertion and Reason are true but Reason is not the correct explanation for Assertion.

Assertion is true and Reason is false.

Both Assertion and Reason are false.

Assertion: E. coli was transformed by inserting the foreign DNA by using Pvul in pBR322.

Reason: It was done to make the transformed cells survive in the culture medium containing ampicillin.

Both Assertion and Reason are true, and Reason is the correct explanation for Assertion.

Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.

Assertion is true and Reason is false.

Both Assertion and Reason are false.

What is the advantage of growing apomictic seeds in crop improvement?

A farmer has two fields in which he wants to grow a cereal crop and a legume. He cannot afford to spend a lot of money on chemical fertilisers to increase the fertility of the soil.

Suggest a way to help him resolve the issue.

Expand the abbreviation MALT.

David is a molecular biologist. He uses a technique to know the amino acids occupy the first and the last positions in the Chain - A and Chain - B of insulin. Name the scientist whose contribution made it possible for David to use this technique.

In a flower, the megaspore mother cell formed four megaspores without undergoing meiosis. One of the four megaspores developed into the embryo sac. What would be the ploidy level of the antipodal cells in this embryo sac?

The diagram given below represents a specific stage of human embryonic development. Identify the stage.

Give a reason for the following:

The diagram given below represents vector pBr322 which was modified by a research scholar Dr. Rayon, but the vector was rejected by his guide.

Give a reason for the following:

The continuous inbreeding of crops may lead to reduced fertility and productivity. However, the self-pollinated crops do not show the ill-effects of inbreeding.

During embryogenesis in dicots, the zygote divides into a basal cell and a terminal cell. The basal cell divides repeatedly to produce a structure called suspensor. Carefully observe the image given below and describe the function of cell – A and cell – B of the suspensor.

Zygote

Given below are the features of Seed A and Seed B. Study them carefully and answer the question that follows.

Identify the type of Seed A and Seed B. Cite one example of each of Seed A and Seed B.

Name the pollinating agent of a flowering plant with large and coloured flowers with sticky stigma. State one characteristic feature of the pollen grains produced in such flowers.

Read the passage given below carefully and answer the questions that follow:

1. Why does the toxic protein kill the insects but not the bacterium?
2. Can the formulation Vecto Bac G be used to eliminate the species of mosquito referred to above? Why?

What happens to an inferior competitor if a superior competitor is present in the same environment?

What happens to an inferior competitor if the superior competitor is removed from the environment?

The diagram given below shows the early embryonic stages of fish, reptiles, birds and humans. Though adult reptiles, birds and mammals breathe air, their embryos possess gills. How does this fact support evolution?

Name the technique used to detect the presence of HIV in the body of an individual, Justify the principle associated with this technique.

Name any two factors responsible for the loss of biodiversity in a geographical region.

Expand the following: 

ZIFT

Write the long form of GIFT.

All STDs do not affect the genital organs. Justify the statement.

The DNA molecules of the same size were extracted from E. coli and Plasmodium vivax. It was discovered that both the DNA molecules had one target site each for the restriction enzyme Hind II. After being digested with Hind II, the DNA fragments were subjected to gel electrophoresis.

With reference to the diagram given below, identify the lanes that represent the DNA fragments of E. coli and Plasmodium vivax respectively. Justify your answer with a reason for each.

The diagram given below represents the image of the cloning vector pUC 18. The gene of interest is inserted and ligated within the gene lacZ. The recombinant DNA is introduced in the host bacterial cell. Explain the method that would help in selection of recombinant colonies from non-recombinant colonies.

Samson and Dorothy surveyed two islands, ‘A’ and ‘B’. They recorded the relevant data in the following format in their research folder:

1. Derive the species-richness for each island.
2. Which island exhibits greater biodiversity? Support your answer with a reason.

The black colour on the beak of finches dominates over the yellow colour. There are 210 individuals with the genotype DD, 245 individuals with the genotype Dd and 45 individuals with the genotype dd. Deduce the frequency of individuals with dominant, heterozygous, and recessive traits.

1. Identify and define the type of immune response that is responsible for the rejection of the grafted organ.
2. Suggest a clinical method by which the rejection of the transplanted organ can be prevented.

1. Classify the biodiversity conservation programme referred to above.
2. Mention any other two methods of conservation which belong to the same category.

Draw a well-labelled diagram of tRNA.

Draw a well-labelled diagram of nucleosome.

Why are the biocontrol agents preferred over the chemical pesticides?

Explain the role of any two biocontrol agents by mentioning their target pests.

Why are some molecules called bioactive molecules?

Mention the respective source and state the specific use of any two bioactive molecules.

1. With respect to this ecosystem, draw a pyramid for each biomass and a pyramid of number.

2. If 20,000 Kcal energy is available at the level of insects, calculate the amount of energy available at the level of big-sized birds.

Consider the following information and answer the question that follows:

Make a single pedigree chart using the above information to show the pattern of inheritance of phenylketonuria (PKU) in the family of Reshma.

Enumerate the cause and the characteristic symptom of PKU.