Biology (Theory) Official 2022-2023 ISC (Science) ISC Class 12 Question Paper Solution

Name the source of thermostable DNA polymerase.

Mention the scientific name of protozoan parasite that causes Amoebiasis.

What is cryopreservation?

The maternal grandfather of a boy is colorblind, but his maternal grandmother is normal. The father of the boy is also normal. What is the probability of this boy being colorblind?

Name the type of antibody that can be transferred through the placenta.

During which phase of the cell cycle, does DNA replication take place? 

How many sets of primers are required in each cycle of PCR?

Define perisperm.

Which one of the following enzymes is used to join DNA fragments? 

DNA polymerase

Ligase

Primase

Endonuclease

What type of ecological pyramid would be obtained from the following data?

Secondary consumer: 120 gm
Primary consumer: 60 gm
Primary producer: 10 gm

Inverted pyramid of biomass

Pyramid of energy

Upright pyramid of numbers

Upright pyramid of biomass

Assertion: A person who has received a cut from a sharp object and is bleeding, needs to be given an anti-tetanus injection.

Reason: Anti-tetanus injection stimulates the production of antibodies for tetanus.

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

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

Assertion is true, but Reason is false.

Both Assertion and Reason are false.

Which one of the following factors is responsible for activation of protoxin into active Bt toxin of Bacillus thuringiensis?

Body temperature

Moist surface of midgut

Alkaline pH of gut

Acidic pH of stomach

Give one significant contribution of the following scientist:

T.R. Malthus

Give one significant contribution to the following scientists:

Prof. R. Mishra

Give a term for the following:

An ART in which eggs are removed from the ovary of the female, fertilised and then placed in her fallopian tube.

Give a term for the following:

Fusion of male gamete and secondary nucleus in angiosperms.

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

NACO

Expand the following abbreviation:

PID

Give a reason for the following:
Cattle avoid browsing on Calotropis plant.

Give a reason for the following:

DNA cannot enter directly into the host cell.

Give one difference between the following pair:

Sites of maturation of B-lymphocytes and T-lymphocytes

Give one difference between the following pairs:

Sources of Opioids and Cannabinoids

Briefly discuss any two methods by which plants avoid self-pollination.

Mention the location and the function of Leydig cells.

What are the vestigial organs?

Give any one example of a vestigial organ in human body.

State Hardy Weinberg's principle.

Give a mathematical expression for Hardy Weinberg's principle.

Riya went to the hospital to meet her sister who was undergoing some treatment. The hospital was crowded with patients suffering from various types of allergies, pneumonia and Ascariasis. Name the disease that Riya is most likely to get infected with. Give one reason for your answer.

State the steps involved in the process of gene therapy for the treatment of ADA-deficiency.

The pedigree chart given below represents the pattern of inheritance of sickle cell anemia in a family. Study it carefully and answer the questions that follow.

1. What is the genotype of the father?
2. What is the phenotype of the mother?

List any three major causes of loss of biodiversity.

Name and explain the technique used for separating DNA fragments and making them available for biotechnology experiments.

Study the diagram given below and answer the questions that follow.

1. Name the cloning vector shown above. In which organism in this cloning vector inserted?

2. Mention any two restriction sites shown in the diagram.

3. Name any two selectable markers shown in the diagram.

Draw a neat labelled diagram of L.S. of anatropous ovule.

Explain the process of sex determination in Grasshopper.

What is the genotype of Turner's Syndrome?

Mention any one symptom of Turner's syndrome.

With the help of neatly labelled diagrams, explain the different types of age pyramids of human population.

1. Which one of the two cities needs a sewage treatment plant?
2. Briefly discuss the steps involved in the treatment of sewage.
3. What will be the effect of sewage treatment on the value of BOD?

The diagram given below shows the life cycle of a malarial parasite. Study it carefully and answer the questions that follows:

1. Name the hosts in which the asexual phase and sexual phase of the life cycle takes place.
2. Identify the infective stage labelled ‘D’.
3. Name the structure labelled ‘A’ and ‘E’.
4. Give any one symptom of malaria.

Explain the components of the structural genes in the Lac operon system in E.coli.

How does the operon function in the presence of lactose?

Given below is the diagram depicting the menstrual cycle in human beings. Study it carefully and answer the questions that follow.

1. Which phases are indicated by ‘C’ and ‘D’?
2. Name the structures labelled ‘F’. What is its role?
3. Explain the changes in the level of progesterone during phases ‘C’ and ‘D’.
4. Which hormone present in the urine confirms pregnancy in human beings?
5. Identify the structure labelled ‘E’. Name the hormone released by it.

According to a survey conducted by the Government of India in the year 1950, the population of the country was 350 million. In the next survey conducted in the year 2010, the population had reached above 1000 million.

1. List any two reasons for this rise in the population.
2. Suggest any two steps which should be taken by the Government to control this rise.
3. How does the population explosion affect the growth of a country?
4. What is the difference between the natural and artificial contraceptive methods? Give one example of each method.

Describe the mechanism of decomposition by explaining the various processes involved in it.