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Biology (Part-IV) (UPSC)

📆 March 25, 2025

Total Questions: 66

41. Consider the following: [2018-11]

(1) Birds

(2) Dust blowing

(3) Rain

(4) Wind blowing

Which of the above spread plant diseases?

Correct Answer: (d) 1, 2, 3 and 4
Solution:Birds (#1) moving through crops can carry pathogens from the infected plant to other plans. Woodpeckers carry spores of tree pathogens. Some plant pathogenic bacteria are carried to short distance by wind (#4). In some places, rain seems to be more important than insects in disseminating the fire blight bacteria, by its washing or splattering effect of rain. (#3). There is only Option D where 1, 3 and 4 are together. So, "d" has to be the correct option.

42. Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss? [2019-1]

1. Hard and waxy leaves

2. Tiny leaves

3. Thorns instead of leaves

Select the correct answer using the code given below:

Correct Answer: (d) 1, 2 and 3
Solution:Thorn is not a 'leaf modification', it is an 'aerial modification of stem". "Spine" is a leaf modification to protect the plant and help in reducing transpiration. So by elimination Answer should 'B'. However, mentioned that "Desert plants have few or no leaves, and the foliage is either waxy, leathery, hairy or needle shaped to reduce water loss through transpiration. Some of them are entirely leafless, with pricks or thrones." So accordingly Answer should be D. Thus, experts were divided between a or d. UPSC has kept 'D' as the official answer.

43. Consider the following statements: [2019-1]

1. Some species of turtle are herbivores

2. Some species of fish are herbivores

3. Some species of marine mammals are herbivores

4. Some species of snakes are viviparous

Which of the statement given above are correct?

Correct Answer: (b) 2 and 3 only
Solution:Cobras, the pythons, the keelbacks don't lay eggs so they're called 'viviparous' as bring out live young. So, #4 is right. Answer could be b, c or d, in all these options, #2 is common so we've to accept 'Some species of fish are herbivores are true without verification.

Depending on the species, sea turtles may be carnivorous (meat eating), herbivorous (plant eating), or omnivorous (eating both meat and plants). So #1 is right and by elimination we are left with answer d: all statements are correct.

44. Which of the following are the reasons for the occurence of multi-drug resistance in microbial pathogens in India? [2019-1]

1. Genetic predisposition of some people.

2. Taking incorrect doses of antibiotics to cure diseases.

3. Using antibiotics in livestock farming.

4. Multiple chronic diseases in some people.

Select the correct answer using the code given below:

Correct Answer: (b) 2 and 3 only
Solution:Overuse and misuse of antimicrobial agents is the single most important cause of development of resistance. They are also used indiscriminately as growth promoters in animals or used to prevent diseases in healthy animals. The antibiotics used in livestock are ingested by humans when they consume food. The transfer of resistant bacteria to humans by farm animals was first noted more than 35 years ago. (says American medical journal). So, #2 & #3 are right this eliminates A and C. Because they don't contain 2 or 3. So, we are at 50:50 between B or D. As per the official UPSC Answer key, correct answer is "b".

45. Which of the following statements is not correct? [2019-1]

Correct Answer: (b) Hepatitis B, unlike Hepatitis C, does not have a vaccine.
Solution:Recombinant DNA technology has allowed the production Vaccines on large scale production. e.g., hepatitis B vaccine produced from yeast. That means Option b is wrong, and we are asked to find wrong option.

46. Consider the following statements: [2020-1]

1. Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.

2. A person's genome can be edited before birth at the early embryonic stage.

3. Human induced pluripotent stem cells can be injected into the embryo of a pig.

Which of the statements given above is/are correct?

Correct Answer: (d) 1, 2 & 3
Solution:CRISPR genome editing tool can be used for accomplishing statement#1.

2020-May: Asia Times says that #3 was done in China. So, #3 is correct, Weare left with the answer "d".

Recall that in 2018 too, UPSC had asked a question from CRISPR genome editing Technology but it was a much simpler one liner question.

47. What is the importance of using Pneumococcal Conjugate Vaccines in India? [ [2020-11]

1. These vaccines are effective against pneumonia as well as meningitis and sepsis.

2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.

3. These vaccines have no side effects and cause no allergic reactions.

Select the correct answer using the code given below :

Correct Answer: (b) 1 and 2 only
Solution:This vaccine is 80% effective against meningitis, sepsis and pneumonia So #1 is right.

Pneumococcal b conjugate vaccines have reduced the burden of antibiotic-resistant bacterial disease globally says the Lancet study-report 2017 So #2 is right.

Various research papers have indicated that vaccine may cause certain side effects and allergic reactions so, #3 is wrong. Accordingly, Answer is b.

48. The term 'ACE2" is talked about in the context of : [2021-1]

Correct Answer: (d) spread of viral diseases
Solution:The SARS-CoV-2 virus enters a human cell through 'ACE2 receptors', which are enzymes that generate small proteins that are useful for the cell.

Therefore, correct answer is "d".

49. With reference to recent developments regarding Recombinant : [2021-1]

1. Genetic engineering is applied in the development of these vaccines.

2. Bacteria and viruses are used as vectors.

Which of the statements given above is/are correct?

Correct Answer: (c) Both 1 and 2.
Solution:Recombinant vector vaccines are bacteria or viruses that are genetically engineered to carry extra genes derived from a pathogen.

So, both statements are right, Therefore, option "C" is correct.

Genetic engineering is applied in the development of Recombinant vector vaccines and it involves techniques to modify the chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus change the phenotype of the host organism.

It include creation of recombinant DNA, use of gene cloning and gene transfer.

These vaccines are made of a viral or bacterial vector and are used as channels for entry into host organisms.

50. In the context of hereditary diseases, consider the following statements : [2021-1]

1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.

2. A child inherits mitochondrial diseases entirely from mother and not from father.

Which of the statements given above is/are correct?

Correct Answer: (c) Both 1 and 2
Solution:This is from the Three parent baby news topic from 2016. Basically the mother has faulty Mitochondrial DNA, so the baby will have a disease. So, to prevent it, you've to remove the mother's egg's nuclear material transfer it to another woman's egg, then fertilize that second woman's egg with the father's sperm.

This disease comes because of mother. #2 is right. Statement 1 is correct Mitochondrial replacement therapy is a form of reproductive invitro fertilization that works on the principle of replacing a women's mitochondrial DNA (mt-DNA) with the donor's healthy one.

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