ISC Class 12 Biology 2024 Question Paper with Solutions, Download PDF

The ISC class 12 Biology exam is one of the most important exams for students aiming to excel in science. Understanding the exam pattern, question types, and solutions is crucial for effective preparation. This article provides the ISC class 12 Biology 2024 question paper along with solutions, helping students analyse their performance and gain clarity on complex topics.

By going through the solved question paper, students can identify important topics, understand the marking scheme, and improve their answering techniques. Whether you want to cross-check your responses or prepare for upcoming exams, this guide will serve as a valuable resource. Download the PDF and make the most of these expert-verified solutions.

ISC Class 12 Biology 2024 Question Paper with Solutions

SECTION–A 20 MARKS
Question 1

(i) In human plasma, five different types of immunoglobulins are found. Which type of immunoglobulin is responsible for allergic reactions? 

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

(iii) Four triplet codons code for the amino acid valine. Three of them are given below. 
GUU GUC GUA
Write the fourth codon.

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

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

(vi) 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. 

(vii) Based on the table given below, identify the type of natural selection taking place

(viii) Give the name of the target pest of gene cry IAc.

(ix) If a person shows the production of interferons in his body, then he is suffering from: 
(a) Malaria (b) Ringworm
(c) Dengue (d) Typhoid

(x) Match the Columns I and II with reference to weeks of pregnancy and development of human embryo. Select the correct option from the choices given below:

(a) I–(P), II–(Q), III–(R), IV–(S)

(b) I–(Q), II–(P), III–(R), IV–(S)

(c) I–(R), II–(S), III–(P), IV–(Q)

(d) I–(S), II–(R), III–(Q), IV–(P)

(xi) 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.
(a) Both Assertion and Reason are true, and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.

(xii)Assertion: Lymphocytes originate and proliferate in primary lymphoid organs.
Reason: Spleen is a secondary lymphoid organ.
(a) Both Assertion and Reason are true, and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Both Assertion and Reason are false.

Answers

Answer 1

(i) Immunoglobulin E (IgE) is the antibody that is responsible for the allergic reactions. 

(ii) The interaction between an orchid and a mango tree is commensalism, which is when one species benefits while the other is unaffected. 

(iii) For example, GUU, GUC, GUA and GUG, all code for the amino acid valine. Thus, GUG is the fourth codon. 

(iv) When a haemophilic man (XhY) marries a carrier woman (XXh) their female progeny will be either XhXh
(haemophilic) or XhX (carrier). Thus, 50% daughters are carriers and 50% are haemophilic. 

(v) Home-made juices are cloudy and turbid because they contain fibres and pectin whereas fruit juices purchased from the market are clear because they are clarified with the enzymes pectinase and proteases. 

(vi) The number of new plants in the pond will be 65 - 50 = 15 Then the natality or the birth rate is obtained by dividing the number of new plants by the original number of plants, i.e., 15/50 = 0.3 

(vii) Both extreme variations, small and large size of seeds of a trait show higher percentage of germination. These are selected to show that extreme phenotypes have a higher fitness than intermediate phenotype. Thus, this type of natural selection is disruptive selection. Consequently, the original population is disrupted into two or more separate groups, that later evolve into new species. 

(viii) Target pest of gene cry IAc produced by Bacillus thuringienis is cotton bollworms.

(ix) Interferons are proteins produced by cells infected by a virus to protect other healthy cells. When the immune system is activated due to a viral infection, white blood cells produce interferons, which are a group of proteins called cytokines. Production of interferons in the body indicates that a person may be suffering from dengue, a viral infection caused by the dengue virus. 

(x) Option (b) is correct. 

(xi) Option (d) is correct.

(xii)Option (b) is correct. 

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