CBSE EXAMINATION PAPER-2024

Populations evolve to maximise their reproductive fitness in the habitat in which they live. Ecologists suggest, the life history of organisms have evolved in relations to the constraints imposed by the biotic and abiotic components of the habitat in which they live. This gets reflected in the population growth pattern of all organisms including humans. Study the population growth curves shown in the given graph and answer the questions that follow :

Read the following passage :

Generally, in eukaryotic cells the average length of a transcription unit along a DNA molecule is about 8,000 nucleotides, so the RNA product of the transcription is also that long. But it only takes about 1200 nucleotides from the above RNA product to translate average sized polypeptide of 400 Amino acids.

In a fertilized ovule of an angiosperm, the cells in which n, 2n and 3n conditions respectively occur are:

Study the table given below: Contraceptive / Contraceptive Method Mode of Action A. The pill I. Prevent sperm reaching cervix B. Condom II. Prevent implantation C. Vasectomy III. Inhibits ovulation D. Copper-T IV. Semen contains no sperm Select the option where contraceptive/contraceptive method are correctly matched with their mode of action.

Identify the category of genetic disorder depicted in the pedigree chart given below:

Turner’s syndrome in humans occurs due to

Which of the options has correct identification of ‘P’, ‘Q’ and ‘R’ in the illustration of ‘Central Dogma’ given below?

Who proposed the mutation theory in favour of organic evolution?

Study the following list of bioactive substances and their action:

Select the option in which the bioactive substances are correctly matched with their action.

The ‘molecular scissors’ fall in the category of:

ELISA technique is based on the principle of:

Assertion (A) : A given fig species can be pollinated only by its partner’ wasp.

Reason (R) : The wasp pollinates the fig inflorescence while searching for suitable egg laying sites.

Assertion (A) : Patents are granted by government to an inventor.

Reason (R) : Patents prevents others from commercial use of an invention.

Assertion (A) : Some aquatic ecosystems have inverted biomass pyramids.

Reason (R) : More energy is required by the organisms occupying higher trophic levels.

(a) Intensely lactating mothers generally do not conceive. Why ?

(b) Our government has intentionally imposed strict conditions for MTP. Why ?

(a) Name the source from which insulin was extracted in earlier times. Why is this insulin no more in use by the diabetic patients ?

(b) Why does the insulin synthesised in the human body undergo processing whereas the insulin produced by Eli Lilly company does not need to undergo any processing ? Explain.

Differentiate between grazing food chain and detritus food chain.

Explain Brood parasitism with the help of a suitable example.

(a) Biodiversity hotspots cover less than 2% of Earth’s land area. Strict protection of these areas can reduce the rate of ongoing extinctions. Explain.

(b) Name any two hotspots in India.

Draw a well labelled diagram of sectional view of male gametophyte/microspore of an angiosperm and write the functions of any two parts labelled. (Any four labels).

(a) A man with blood group ‘A’ marries a woman with blood group ‘AB’. The first child born to them has blood group ‘B’. Work out a cross to find the genotype of the father. Give the possible blood groups and their genotypes of the children that could be born to this couple. (Use a Punnet square).

(b) State the basis of ‘ABO’ blood grouping in humans.

(a) Whose skulls ‘A’, ‘B’, and ‘C’ are shown below ? Which of the two are more similar to each other ?

(b) Name the (i) ape like (ii) man like primates that existed 1.5 million years ago.

(a) Name the group of drugs whose skeletal molecule is shown below

(b) How are such drugs consumed ?

(c) Name the human body organ affected by the consumption of these drugs.

Draw a schematic diagram of an antibody molecule and label any 4 parts. Mention their chemical nature. Name the cells which produce them.

Explain the role of the following during the sewage treatment :

(a) flocs

(b) anaerobic sludge digester

Study the steps shown below, that are carried during a specific technique :

(a) Identify the steps ‘A’ and ‘D’ in the diagram.

(b) What does ‘B’ represent ?

(c) Write what is ‘C’ ? Name its source organism.

(d) Mention the use of this technique in molecular diagnostics.

Explain the role of transgenic animals in :

(a) Production of Biological products

(b) Studying diseases

(c) Chemical safety testing

The given diagram shows the sectional view of a seminiferous tubule of Human testis :

(i) Name and describe the process depicted in the diagram which results in the development of spermatozoa.

(ii) dentify the cell where you are seeing a cluster of spermatozoa attached in the diagram. Write the function of the cell.

Observe the picture of Commelina plant bearing two types of flowers given above.

(i) Identify the two types of flowers labelled ‘A’ and ‘B’ in the picture.

(ii) Compare the two types of flowers with reference to :

• Characteristic feature

• modes of pollination

  (ii) List any two ‘out breeding devices’ in flowering plants. Explain why do plants develop such devices.

Study the schematic diagram given below and answer the questions that follow :

(i) Identify the polarity from ‘X’ to ‘ X ’ in the mRNA segment shown. Mention how many more amino acids can be added to the polypeptide that is being translated and why.

(ii) Write the initiating codon for translation, its anticodon and the amino acid it codes for.

(iii) Explain the charging of an adaptor molecule. Why this molecule needs to be charged ?

1. Why is sickle-cell anaemia, a human blood disorder so named ?

2. Explain the genetic basis that results in the expression of this disorder.

3. Work out a cross to explain how normal parents may have a sicklecell anaemic child.

1. Write the symptoms of malaria in human and explain what causes these symptoms.

2. Describe the different steps in the sexual mode of reproduction in the life cycle of a malarial parasite from the time of its initiation till where it is completed and ready to start a fresh cycle.