UPSC Prelims PYQ › Science & Environment › Biology & Human Body

Biology & Human Body — UPSC Prelims Science & Environment previous year questions — page 6

213 solved previous year questions on Biology & Human Body, papers from 1993 to 2023, drawn from UPSC CSE Prelims, UPPCS, UPSC CDS. Each carries the printed answer key and the explanation from the source compilation.

1. #201Full-length test
   In the context of the human body, which of the following statements best describes the term 'molecular motors?
   • AThey are the tiny organelles that are found only in the cells of muscle tissues in the human body
   • BThey are the proteins that convert chemical energy into mechanical movement
   • CThey are the enzymes that break down Adenosine Triphosphate (ATP) into smaller molecules
   • DThey are the nucleic acids that regulate gene expression in cells
   Answer: (B) They are the proteins that convert chemical energy into mechanical movement
   Explanation

   Option b is the correct a is incorrect: Molecular motors are the proteins found in almost all kinds of cells of the body. of molecular motors such as dynein, kinesin, are found in all types of cells. They play an in intracellular transport, cell division and other in addition to muscle b is correct: Molecular motors are the proteins chemical energy into mechanical movement. are associated with the cytoskeleton. A a system of protein filament in cytoplasm of a that gives the cell shape and capacity for The molecular motors (motor proteins) use of ATP hydrolysis to power the cellular processes l c is incorrect: Molecular motors use ATP as of energy, but they do not break it down molecules. Rather, they use energy released by to generate d is incorrect: Nucleic acids (DNA, RNA) are motors. They play an important role in and other cellular processes; they do not movement like molecular motor

2. #202Full-length test
   With reference to 'Polymerase Chain Reaction (PC consider the following statements: 1. It is a technique used for early diagnosis of diseases. 2. It can be used to detect mutations in genes in suspected cancer patients. 3. HIV in suspected AIDS patients cannot be detected using this technique.How many of the above given statements are correct?
   • AOnly one
   • BOnly two
   • CAll three
   • DNone
   Answer: (B) Only two
   Explanation

   Option b is the correct Chain Reaction (PCR) is a laboratory to amplify a specific segment of DNA. It allows make many copies of a particular DNA sequence efficiently. l is correct- Using conventional methods (serum and urine analysis, etc.) early detection disease is not possible. 'Recombinant DNA Chain Reaction (PCR)' and 'Enzyme Assay (ELISA)' are some of the serve the purpose of early 2 is correct- PCR is being used to detect genes in suspected cancer 3 is incorrect- PCR is now routinely used in suspected AIDS patients. Important Tips Limitations of PCR technique Contamination PCR is susceptible to contamination, which can lead to false-positive results. PCR Inhibitors: Some samples may contain substances that can inhibit the PCR reaction, preventing efficient amplification. Target Specificity: PCR relies on the design of specific primers that bind to the desired target DNA sequence.

3. #203Full-length test
   Consider the following statements regarding the difference between Phenotype and Genotype of an organism: 1. Phenotype is the physical appearance while Genotype is genetic composition of an organism. 2. Phenotype are partly inherited while Genotype is not inherited during the reproduction process.Which of the following statements given above is/are correct?
   • A1 only
   • B2 only
   • CBoth 1 and 2
   • DNeither 1 nor 2
   Answer: (A) 1 only
   Explanation

   Option a is the correct 1 is correct. The phenotype is the of an organism, while the Genotype is the of an organism. Phenotype is observable and expression of the genes of an individual. We can hair colour, eye colour, height, weight, skin colour, cannot look at genes responsible for these the observable physical look is the phenotype while genes responsible for such characters present DNA of cell of the individual is 2 is incorrect. Genotypes are partly an individual to the offspring as one of the during the reproduction process. The of the organisms, which may or may not in the next generation. The same the same phenotype in a particular is not inherited. It appears outside the body, appearance

4. #204Full-length test
   Which of the following statements best describes the term "monoclonal antibodies"?
   • AAntibodies developed naturally through live attenuated vaccination L { }
   • BAntibodies derived from different immune cells to aid our immune system
   • CAntibodies developed by cloning the embryonic stem cells
   • DAntibodies generated by identical B cells which are clones from a single parent cell
   Answer: (D) Antibodies generated by identical B cells which are clones from a single parent cell
   Explanation

   Option d is the correct antibodies are similar kinds of that mimic the activity of the immune system The term monoclonal antibodies target Monoclonal antibodies are generated B cells which are clones from a single parent mimic the immune system's ability to fight off a is incorrect: Live attenuated vaccines version of the living virus or bacteria that has so that it does not cause serious disease in healthy immune systems. As live attenuated the closest to a natural infection, they are good the immune b is incorrect: An antigen injected into them to produce and secrete high levels of the blood. Several months after repeated blood (plasma, serum) i collected, and antibodies The antibodies gene ated by this method are (and not monoclonal) antibodies because derived from different B cell c is incorrect: Stem cells are cells that can differentiate into specialized can divide to produce more

5. #205Full-length test
   Consider the following statements with reference to the concept of Civil Registration System (CRS) in India, popularly known as the birth and death registration system: 1. The Registrar General of India oversees the functioning of CRS. 2. Registration of birth and death is mandatory under the provisions of Registration of Births and Deaths (RBD) Act. 3. It falls under the Central List of seventh schedule of the Constitution of India.How many of the above given statements are correct?
   • AOnly one
   • BOnly two
   • CAll three
   • DNone ulm
   Answer: (B) Only two
   Explanation

   Option b is the correct registration is the process of recording vital events births, deaths, marriages, divorces, and adoptions by 1 is correct: The Registrar General, India the Central level coordinates and unifies the activities throughout the country and at the same enough scope for the State Governments to efficient system of registration suited to the the respective administration and notify 2 is correct: Under the provisions of RBD the registration of birth and death is mandatory. of births, still births and deaths are registered at of occurrence of the event i.e where the event The normal period of reporting the event is 21 its occurrence, however, the event can be the normal period under delayed registration Section 13 of the RBD 3 is incorrect: Civil registration system the Concurrent list of seventh schedule (not list) of the Constitution of India

6. #206Full-length test
   Which of the following statements is correct about the "immunity gap"?
   • AIt is a tendency of the body to repeat its immune response based on the first infection or vaccination, when it comes across variant of the same pathogen again
   • BIt is the gap between the immunity gained after first infection and the required immunity to fight a pathogen. 96
   • CIt refers to preventing an infectious disease from spreading, by immunizing a certain percentage of the population
   • DIt can develop when our immune system essentially gets a break from being exposed to a mix of common pathogens
   Answer: (D) It can develop when our immune system essentially gets a break from being exposed to a mix of common pathogens
   Explanation

   Option d is the correct a is incorrect: Immune imprinting (not gap) is a tendency of the body to repeat response based on the first variant it through infection or vaccination - when it comes newer or slightly different variant of the same bis incorrect: Hybrid immunity (not the is gained from a previous infection plus vaccines the primary doses or both primary and booster recent study, Infectious Diseases suggests that a offers a "higher magnitude and durability" as compared to infection alone, emphasizing for c is incorrect: Herd immunity (and not gap) refers to preventing an infectious spreading by immunizing a certain percentage of dis correct: An immunity gap can develop when system essentially gets a break from being a mix of common pathogens-bacteria, viruses, and other that can cause illness. When we are going work, the gym, or restaurants-we come in all types of pathogens that g

7. #207Full-length test
   Which of the following vector borne diseases are caused by virus and are transmitted through mosquitoes? 1. Japanese Encephalitis 2. Plague 3. MalariaSelect the correct answer using the codes given below
   • A1 only
   • B1 and 3 only
   • C2 and 3 only
   • D1, 2 and 3
   Answer: (A) 1 only
   Explanation

   Option a is the correct 1 is correct. Japanese encephalitis is a mosquito borne viral infection. It is the leading cause of in 2 is incorrect. Plague is a bacterial disease humans and other mammals. Humans usually after being bitten by a rodent flea that is carrying bacterium or by handling an animal infected 3 is incorrect. Malaria is a disease caused parasites. The parasites are transmitted through the bites of infected mosquitoes { } Mosquito Aedes Chikungunya Virus Dengue Virus Lymphatic Parasite filariasis Rift Valley fever Virus Yellow Fever Virus Zika Virus Anopheles Lymphatic Parasite filariasis Malaria Parasite Culex Japanese Virus encephalitis Lymphatic Parasite filariasis West Nile fever

8. #208Full-length test
   Consider the following statements about the drinking water specifications laid down by the Bureau of Indian Standards (BIS):1. pH value of the drinking water shall not be above 7.0 under any circumstances. 2. Presence of Chlorides is allowed up to a specified limit. 3. E. coli bacteria should be present in the drinking water. 4. BIS did not provide any specific standards about the Total Dissolved Solids (TDS) in the drinking water.How many of the above given statements are correct?
   • AOnly one
   • BOnly two
   • COnly three
   • DAll four
   Answer: (A) Only one
   Explanation

   Option a is the correct Bureau of Indian Standards (BIS) has standards to ensure the availability of safe for Indian citizens. This standard provides for under two major heads, namely acceptable limits, in case of unavailability of an Any water sample would stand unfit for if they found to be in non-conformity limits. Permissible limit (In the absence Test parameter Acceic.able limit of alternate source of water) pH value 6.5--8.5 No relaxation Turbidity 1 5 Shall not Shall not E. coli presence present in in sample sample ! 7 Chlorides, Max i 250 1000 I mg/1 (max) Total dissolved i 500 2 solids, mg/I (Max) the above table we can conclude 1 is incorrect: Water of pH'. 'lai.ue between. 8.5 is allowed for the drinking 'l'r.i 2 is correct: Pres,, of fri. water up to 250 mg per litre is acceptable circumstances. In the absence of alternate source presence of chloride up to 1000 mg per litre i

9. #209Full-length test
   Which of the following can be the most likely consequences for human health due to the improper disposal of biomedical waste? 1. Spread of hepatitis virus infections 2. Increase of antimicrobial resistance 3. Spread of Sickle cell Anaemia 4. Health hazards caused by exposure to radioactive waste 5. Increase in the incidence of coronary artery diseaseSelect the correct answer using the code given below
   • A1, 2, 4 and 5 only
   • B1, 2 and 4 only
   • C2 and 4 only
   • D1, 2, 3, 4 and 5 { }
   Answer: (B) 1, 2 and 4 only
   Explanation

   Option b is the correct 1 is. correct. Medical waste contains a wide pathogens. Human Immunodeficiency Virus (HIV) viruses spearhead an extensive list of diseases documented to have spread through waste. Tuberculosis, pneumonia, diarrhoea, cough etc. are other common diseases spread improper waste 2 is correct: The biomedical wastes aggravate of Anti-Microbial Resistance (AMR). A caused by biomedical waste includes which spread from health facilities into and may increase the risk of AMR in entering their 3 is incorrect: Sickle cell anaemia is a form of blood disorder, sickle cell disease. Sickle affects red blood cells, turning them from discs into stiff and sticky sickled cells. Sickle. is not related to biomedical 4 is correct. Hospitals are increasingly isotopes for diagnostic and The main radioisotopes used in hospitals etc. material can come from research in liquid form. These have

10. #210Full-length test
    In the context of plasmid, consider the following statements: 1. They are chromosomal DNA. 2. They are most commonly found in bacteria. 3. They are essential for the functioning of the cell.How many of the above given statcnents are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (A) Only one
    Explanation

    Option a is the correct National Congress (founded in 1885) and (founded in 1906) were two of the most India political parties representing Indian the British during the freedom 1 is correct: Both the League and that Indians should have a greater role in process of their country. This is one of the brought them together during the Lucknow Pact They demanded that legislatures at both central levels be expanded and more elected given 2 is incorrect: Separate Electorates by the Morley Minto Reforms (Indian 1909). While this was welcomed by the League, vociferously opposed it. Congress it was the representative of both Hindus and that these two religions were not two different interests can never align. They believed that would widen the communal rift and create Muslims and Hindus

11. #211Full-length test
    Consider the following pairs regarding various processes related to DNA and RNA:New copies of genome length RNAs are made 2. Transcription Information in DNA is qopied into RNA 3. Translation of amino acidsHow many of the above given pairs are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (C) All three
    Explanation

    Option c is the correct answer. Pair 1 is correctly matched. RNA replication is the process by which new copies of genome-length RNAs are made. RNA replication occurs in the cytoplasm and is carried out by the. viral RNA polymerase. Pair 2 is correctly matched. Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA) DNA replication is the process of copying the DNA in a cell so that there are two copies. This is done in preparation for cell division, or mitosis. Before a cell divides, the DNA must be copied so that there is a copy for each of the resulting daughter cells. Transcription copies the DNA into RNA and involve the generation of a new molecule of nucleic acids, either DNA or RNA. DNA transcription happens in preparation for protein translation. Transcription of DNA is the method for regulating gene expressio

12. #212Full-length test
    Consider the following statements about the Bose-Einstein condensate (BEC): 1. It exists at very cold temperatures, almost near the Absolute Zero. 2. It has been found occurring naturally in very cold depths of polar waters.Which of the above given statements is/are correct?
    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
    Answer: (C) Both 1 and 2
    Explanation

    Option c is the 1 is correct. Genetic modification of adding a specific stretch of DNA into the giving it new or different characteristics. This changing the way the plant grows or making to a particular disease. The new DNA of the GM plant's genome which the seeds these plants will 2 is correct. There ar.e many viruses. that transfer their DNA into a host cell normal part of their life For GM plants, most frequently used is called 3 is incorrect. Currently, genetfc is regulated in India. The regulatory transgenic crops in India consists of guidelines like Policy, 2002, Recombinant 1990, Guidelines for research in transgenic 4 is correct. Genetic modification of plants naturally and unnaturally. Genes from one can naturally integrate into the genomes of more Some food plants can carry genes that originate transferred both by nature and by Solution: Option b is the correct Technology is t

13. #213Full-length test
    Which of the following describes the Chandrashekhar Limit?
    • AIt is the maximum mass a white dwarf star can have before becoming unstable
    • BIt is the minimum distance after which an object cannot return to Earth
    • CIt is the limit below which electron degeneracy pressure is not enough to prevent gravity
    • DIt is the gravity of Sun, which holds together all the planets in our solar system
    Answer: (A) It is the maximum mass a white dwarf star can have before becoming unstable
    Explanation

    Option a is the correct Chandrasekhar Limit of 1.4 solar masses, is maximum mass a white dwarf star can still remain a white dwarf (though this limit does depending on the metallicity). Above this degeneracy pressure is not enough to from collapsing the star further into a neutron black hole. The limit is named after the Nobel Chandrasekhar, who first proposed the 1931

More Science & Environment topics