Biology (Theory) official 2023-2024 ISC (Science) ISC Class 12 Question Paper Solution

In human plasma, five different types of immunoglobulins are found.

Which type of immunoglobulin is responsible for allergic reactions?

Some orchids live on the branches of mango trees. Name the type of interaction that exists between the mango tree and the orchid.

Four triplet codons code for the amino acid valine. Three of them are given below.

GUU GUC GUA

Write the fourth codon.

A haemophilic man marries a carrier woman and they have a daughter. What is the probability of their daughter being haemophilic?

Home-made fruit juices are turbid, while the bottled ,fruit juices purchased from the market are clear. Give a reason for this difference.

The number of lily plants in a pond was found to be 50. After one year, the number. increased to 65. Calculate the natality of lily plants.

Based on the table given below, identify the type of natural selection taking place.

Give the name of the target pest of gene cry 1 Ac.

If a person shows the production of interferons in his body, then he is suffering from ______.

Malaria

Ring worm

Dengue

Typhoid

Match the columns I and II with reference to weeks of pregnancy and the development of a human embryo. Select the correct option from the choices given below:

I - (P), II - (Q), III - (R), IV - (S)

I - (Q), II - (P), III - (R), IV - (S)

I - (R), II - (S), III - (P), IV - (Q)

I - (S), II - (R), III - (Q), IV - (P)

Assertion: In a bioreactor, it is not necessary to maintain sterile ambience.

Reason: Sterile conditions promote the growth of unwanted microbes in the culture medium.

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: Lymphocytes originate and proliferate in primary lymphoid organs.

Reason: Spleen is a secondary lymphoid organ.

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.

The equipment shown below is used for the separation of DNA fragments.

Name the chemical used to visualise the movement of DNA fragments in the gel.

In humans, somatic gene therapy was carried out to correct an immunodeficiency disease. Name this disease.

The pedigree chart given below represents the pattern of inheritance of thalassemia in a family.

What could be the genotype of the affected male?

In a karyotype analysis, X and Y chromosomes represent sex chromosomes.

Name the scientist who discovered the X chromosome.

The following is well-known abbreviation, which have been used in this chapter. Expand to its full form:

NACO

The figure given below shows the early stage of the development of microsporangium.

Name the hypodermal cell labelled '1' which divides periclinally.

Give a reason for the following:

The second half of the menstrual cycle is called the luteal phase as well as the secretory phase.

Give a reason for the following:

Streptokinase is administered to the patients having myocardial infarction.

Name any two Cu-ions releasing IUDs.

Explain any two ways by which IUDs devices act as contraceptives.

A population of 200 fruit flies is in Hardy Weinberg equilibrium. The frequency of the allele (a) 0.4. Calculate the following:

Frequency of the allele (A).

A population of 200 fruit flies is in Hardy Weinberg equilibrium. The frequency of the allele (a) 0.4. Calculate the following:

The number of homozygous dominant fruit flies.

A population of 200 fruit flies is in Hardy Weinberg equilibrium. The frequency of the allele (a) 0.4. Calculate the following:

The number of homozygous recessive fruit flies.

A population of 200 fruit flies is in Hardy Weinberg equilibrium. The frequency of the allele (a) 0.4. Calculate the following:

The number of carrier fruit flies.

Jacob is genetically a carrier of the disorder that affects the shape of the RBCs, as shown in the diagram below. His son James suffers from the same disorder.

1. Give the biochemical reason for the disorder that changes the shape of the RBCs, as shown above.
2. Draw a Punnett square to show the genotype of the mother of James.
3. Name and define the type of 'point mutation' responsible for this disorder.

The diagram given below shows the three types of endosperms in angiosperms.

Type 1	Type 2	Type 3

1. Identify the three types of endosperms shown above.
2. Name the type of endosperm which commonly occurs in polypetalous dicots.

The diagram given below shows the various steps in spermatogenesis.

1. Name the parts labelled '1', '2' and '3'.
2. Name the process by which part '3' changes to part '4'.

Write the scientific name of the filarial worm that causes filariasis.

Write the mode of transmission for the following diseases:

Filariasis

Write the scientific name of the causative agent of the following diseases:

Typhoid

Write the mode of transmission for the following diseases:

Typhoid

A male plant bearing red flowers was crossed with a female plant bearing yellow flowers. In the F₁ generation, all the flowers were orange in colour.

Give a reason to explain the change of colours in F₁ generation.

A male plant bearing red flowers was crossed with a female plant bearing yellow flowers. In the F₁ generation, all the flowers were orange in colour.

Mention the ratio of red flowers, yellow flowers and orange flowers in the F₂ generation.

Microbes are useful to human beings in diverse ways. Give the biological name of the following microbe:

Lactic acid producing bacterium.

Microbes are useful to human beings in diverse ways. Give the biological name of the following microbe:

Microbe known as Baker's yeast.

Microbes are useful to human beings in diverse ways. Give the biological name of the following microbe:

Fungus which helps in the production cyclosporin-A.

Microbes are useful to human beings in diverse ways. Give the biological name of the following microbe:

Microbe used in the production of statins.

The diagram given below is the L.S. of a typical fruit.

1. Identify the parts labelled '1', '2' and '3'.
2. State the difference between a true fruit and a false fruit.
3. What is the significance of the formation of fruit in angiosperms?

Suneeta is planning an experiment to clone a gene in a vector. So, she has to choose a good cloning vector.

Which one of the vectors shown below should she choose? Justify your answer by giving two reasons.

Vector A	Vector B	Vector C

Study the two figures shown below that represent two growth models.

Figure A	Figure B

1. Which one of the two figures represents an unlimited supply of nutrients? Give a reason.
2. Which figure depicts a challenge to population growth?
3. Explain the term reproductive fitness.
4. Give the mathematical expressions for Figure A and Figure B.

The diagram given below represents the schematic structure of proinsulin, which undergoes certain modifications before it becomes a fully functional insulin.

Study the diagram carefully and answer the questions that follow:

1. State the change the proinsulin undergoes to become fully functional.
2. Name the modern scientific technique used for the production of human insulin.
3. How are the two polypeptide chains of the fully functional insulin held together?

A patient was given an anti-retroviral drug by the doctor.

Which disease was the patient diagnosed with?

A patient was given an anti-retroviral drug by the doctor.

Mention any one symptom of HIV disease.

A patient was given an anti-retroviral drug by the doctor.

Give the scientific name of the causative agent of HIV disease

A patient was given an anti-retroviral drug by the doctor.

Which method was used to diagnose HIV disease?

A patient was given an anti-retroviral drug by the doctor.

What is the role of Reverse Transcriptase and Integrase in the life cycle of a retrovirus?

Draw a neat and well labelled diagram of T.S. of anther.

Draw a neat and well labelled diagram of T.S. of the mammalian ovary.

The table given below shows the Area, Y-intercept and regression coefficient of the continents namely, Africa and Europe. Study the table carefully and answer the questions that follow:

1. Calculate the species richness (S) of each continent.
2. Which of these continents shows a higher biodiversity?
3. State any two factors that cause an increase in biodiversity.

1. Will this pollination give the desired results? Give a reason for your answer.
2. What is geitonogamy? Why is it considered equivalent to cross-pollination in ecological context and self-pollination in genetic context?

1. Explain the process of fertilisation in angiosperms.
2. What is the precise location and function of filiform apparatus in the embryo sac of angiosperms?
3. Fruits and seeds are generally formed due to fertilisation. Name the process involved in the production of the following without fertilisation:
   1. Fruits
   2. Seeds

The diagram given below shows the process of decomposition in the forest ecosystem.

Observe the diagram carefully and answer the questions that follow.

1. Why is the breaking down of complex organic matter an important event in the ecosystem?
2. The forest soil has a higher humus content than the desert soil. Give a reason to justify this statement.
3. Earthworms and centipedes play an important role in the decomposition process of forest ecosystems. At which stage of the decomposition are these organisms involved?
4. The net annual primary productivity of a particular wetland ecosystem is found to be 8,000 kcal/m2 per year. If respiration by the aquatic producers is 11,000 kcal/m2 per year, calculate the gross primary productivity for this ecosystem.

Griffith conducted a series of experiments on mice with two different strains of the bacterium Diplococcus pneumoniae.

1. Describe the entire procedure for this experiment.
2. Write the conclusion of this experiment.
3. What would have been the result of the experiment if both strains of bacteria were first heat-killed, mixed and then injected in the mice?