CBSE EXAMINATION PAPER-2024
BIOLOGY
(Solved)
General Instructions :
Read the following instructions carefully and follow them :
- This question paper contains 44 questions. All questions are compulsory.
- This question paper is divided into 5 sections.
- Section A – questions number 1 to 14 are case based questions
- Section B – questions number 15 to 29 are multiple choice questions
- Section C – questions number 30 to 33 are very short answer
- Section D – questions number 34 to 42 are short answer
- Section E – questions number 43 to 44 are long answer
- There is no overall choice given in the question paper. However, an internal choice has been provided in few questions.
- Use of calculator is NOT allowed.
Section A
Read the following passage and answer the questions that follow.
Isn't it incredible that India's land area is only 2.4 per cent of the world's total land area whereas its share of the global species diversity is an impressive 8.1 per cent! However, in these estimates of species, prokaryotes do not figure anywhere.
Biologists are always keen on collecting data with respect to species diversity observed in different regions of the world. The data collected based on the survey conducted for species richness of groups of mammals in three different regions of the world is shown in the bar graph given below :
(a) Why is the species richness maximum in Region III in the bar graph ?
Study the diagram given below that shows the steps involved in the procedure of selecting transformed bacteria and answer the questions that follow :
(a) Identify the colony that has got transformed. Justify your answer.
(b) What are the sites in a plasmid called where ampicillin and tetracycline resistance genes are inserted ? State their role in genetic engineering.
(c) Name two enzymes playing an important role in genetic engineering.
Study the diagram given below that shows the steps involved in the procedure of selecting transformed bacteria and answer the questions that follow :
(1) Name two enzymes playing an important role in genetic engineering
(2) Identify the colony that has got transformed. Justify your answer.
(3) What are the sites in a plasmid called where ampicillin andtetracycline resistance genes are inserted ? State their role in genetic engineering.
(4) State the role of -galactosidase in insertional inactivation.
Read the following passage and answer the questions that follow.
Isn't it incredible that India's land area is only 2.4 persent of the world total land area whereas its share of the global species diversity is an impressive 8·1 per cent ! However, in these estimates of species, prokaryotes do not figure anywhere. Biologists are always keen on collecting data with respect to species diversity observed in different regions of the world. The data collected based on the survey conducted for species richness of groups of mammals in three different regions of the world is shown in the bar graph given below :
Read the following passage and answer the questions that follow.
Isn't it incredible that India's land area is only 2.4 % of the world 's total land area whereas its share of the global species diversity is an impressive 8·1 per cent ! However, in these estimates of species, prokaryotes do not figure anywhere. Biologists are always keen on collecting data with respect to species diversity observed in different regions of the world. The data collected based on the survey conducted for species richness of groups of
mammals in three different regions of the world is shown in the bar graph given below :
Read the following passage and answer the questions that follow. 4
total land area whereas its share of the global species diversity is an
impressive 8·1 per cent ! However, in these estimates of species,
prokaryotes do not figure anywhere.
Biologists are always keen on collecting data with respect to species
diversity observed in different regions of the world. The data collected
based on the survey conducted for species richness of groups of
mammals in three different regions of the world is shown in the bar
graph given below :
Read the following passage and answer the questions that follow. Isn't it incredible that India's land area is only 2-4 per cent of the world's total land area whereas its share of the global species diversity is an impressive 8.1 per cent! However, in these estimates of species, prokaryotes do not figure anywhere.
Biologists are always keen on collecting data with respect to species diversity observed in different regions of the world. The data collected based on the survey conducted for species richness of groups of mammals in three different regions of the world is shown in the bar graph given below :
(1) Why is the species richness maximum in Region III in the bar graph ?
(2) Why is the species richness minimum in Region I in the bar graph ?
(3) Why is it that prokaryotes do not have an estimated number of their species diversity as seen in plants and animals ? Explain.
(4) Plants and animals do not have uniform diversity in the world but show rather uneven distribution. Mention what this kind of diversity is referred to as.
Section B
In which of the following plants are both male and female flowers born on the same plant and the mode of pollination can be geitonogamy or xenogamy?
The correct option is 'Maize.' In maize plants, both male and female flowers can be found on the same individual plant, allowing for self-pollination (geitonogamy) as well as cross-pollination (xenogamy) if pollen is transferred from one plant to another.
Which one of the following hormones is secreted by the human placenta that helps in the maintenance of pregnancy?
The periodic abstinence by a couple for family planning should be from:
You know that there are twenty different types of naturally occurring amino acids and four different types of bases in the DNA. A combination of 3 such bases code for a specific amino acid. If instead there are 96 different amino acids and 12 different bases in the DNA, then the minimum number of combinations of bases required to form a codon is:
The type of bond represented by the dotted line in a schematic polynucleotide chain is:
In which of the following conditions/diseases is there a substantial increase in the activity of mast cells observed in the human body?
Lactobacillus that sets milk into curd is categorised as:
Which one of the following transgenic animals is being used to test the safety of the polio vaccine?
Restriction Endonuclease Hind II always cuts DNA molecules at a particular point by recognising a specific sequence of:
The improved trait that is found in the genetically modified transgenic crop Golden rice is:
The rate of formation of new organic matter by consumers, and the biomass available for consumption of herbivores as well as decomposers are referred to as:
Assertion (A) : The laws of our country permit legal adoption and it is as yet, one of the best methods for childless couples looking for parenthood.
Reason (R) : Emotional, religious and social factors are no deterrents to the legal adoption of orphaned and destitute children in India.
Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). While legal adoption is indeed permitted and a method for childless couples, the assertion does not depend on the emotional, religious, and social factors mentioned in the reason.
Assertion (A) : Linked genes do not show dihybrid F2 ratio 9 : 3 : 3 : 1.
Reason (R) : Linked genes do not undergo independent assortment.
Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A). Linked genes, being located close together on the same chromosome, tend to be inherited together and do not assort independently, leading to a dihybrid ratio of 9:3:3:1 not being observed.
Assertion (A) : Agrobacterium tumefaciens is a pathogen of several monocot plants.
Reason (R) : It is able to deliver a piece of DNA known as T-DNA to transform normal plant cells into a tumor.
Assertion (A) is false, but Reason (R) is true. Agrobacterium tumefaciens primarily affects dicot plants, not monocots, which makes the assertion incorrect. However, the reason provided is true, as this bacterium does deliver T-DNA that causes the transformation of host plant cells into tumor-like structures.
Assertion (A) : Indian Government has set up an organisation known as GEAC to decide the validity of GM research.
Reason (R) : Genetic modification of organisms has no effect when such organisms are introduced in the ecosystem.
Assertion (A) is true, as the Genetic Engineering Appraisal Committee (GEAC) is indeed responsible for evaluating the research and validity of genetically modified organisms (GMOs) in India. However, Reason (R) is false because genetic modifications can have significant ecological effects when GMOs are introduced into ecosystems, which is one of the main concerns that GEAC addresses. Hence, the correct option is: Assertion (A) is true, but Reason (R) is false.
Section C
Identify A, B, C and D in the table given below:
Section D
Explain the mode of action of contraceptive pills taken by human females. Mention the schedule to be followed for effective outcome.
(a) Name and write two characteristics of the type of DNA that forms the basis of DNA fingerprinting technique.
(b) Mention any two applications of this technique.
(a) Explain the significance of the experiment carried out by S.L. Miller. Name the scientists whose hypothesis prompted him to carry out this experiment.
(b) How does meteorite analysis favour this hypothesis ?
Identify A, B, C, D, E and F in the table given below :
In a family, the father, the daughter and the son are colour blind, whereas the mother has normal vision. Do you think the son and the daughter have inherited the disease from their father ? Work out a cross to justify your answer.
(i) What are transgenic animals ?
(ii) Name the first transgenic cow and state its importance.
(a) Explain how it is ensured that the orchid Ophrys is pollinated by a specific species of bee.
(b) Describe co-evolution with the help of this example.
(i) Explain the convention for naming EcoRI. 2
(ii) With the help of an illustration only, show the action of EcoRI on a DNA Polynucleotide.
Explain the development of male gametophyte in an angiosperm.
Section E
To determine the unknown genotype of a tall pea plant with violet flowers, one can perform selfing crosses. Pea plants can be classified as homozygous dominant (TT) or heterozygous (Tt) for tallness, and similarly for flower color. For the violet flowers, we assume violet is dominant over white, thus the genotypes could be either homozygous violet (VV) or heterozygous (Vv). Let's begin selfing a tall violet flower plant, assuming its genotype is TtVv. The cross will be TtVv × TtVv. 1. **Genotypic Ratio:** - 1 TT VV (Taller and violet) - 2 Tt VV (Tall and violet) - 1 tt VV (Dwarf and violet) - 2 TT Vv (Tall and violet) - 4 Tt Vv (Tall and violet) - 2 tt Vv (Dwarf and violet) Total = 1 TT VV + 2 Tt VV + 1 tt VV + 2 TT Vv + 4 Tt Vv + 2 tt Vv = 9 Tall Violet : 3 Dwarf Violet 2. **Phenotypic Ratio:** - The tall plants (TT or Tt) dominate over dwarf (tt). Thus: - Total Tall: 9 - Total Dwarf: 1 - Thus, the phenotypic ratio is 3 Tall Violet: 1 Dwarf Violet. Following these selfing methods provides a clear way to understand the genotype of the tall violet flower plant, confirming its traits and ratios through systematic analysis and genetic prediction.
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