116 previous year UPSC Prelims questions on zoology and human biology make this the largest Science chapter, from 1996 to 2025. UPSC asks about the classification of animals, genetics and genetic disorders, diseases and their vectors, the human body, and the biology of viruses and parasites. The explanations give the reasoning behind each fact.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 91–100 of 116 questions
Aerobic respiration is the process by which glucose is completely oxidized in the presence of oxygen to produce carbon dioxide, water, and energy (in the form of ATP). The overall reaction is:
C₆H₁₂O₆ + 6O₂ 6CO₂ + 6H₂O+ Energy (ATP)
Fish, especially oily fish like salmon, mackerel, and sardines are rich in polyunsaturated fatty acids (PUFAs) such as omega-3 fatty acids (e.g., EPA and DHA). These fatty acids are essential for various health benefits such as:
Reducing the risk of cardiovascular diseases.
Improving brain function and development.
Reducing inflammation.
| List-I (Disease) | List-II (Organism) |
|---|---|
| A. Malaria | 1. Fungi |
| B. Poliomyelitis | 2. Bacteria |
| C. Tuberculosis | 3. Virus |
| D. Ringworm | 4. Protozoan |
A is matched with 4: Malaria is Caused by protozoan parasites of the genus Plasmodium (e.g., Plasmodium falciparum, Plasmodium vivax), transmitted through the bite of infected female Anopheles mosquitoes. India’s National Malaria Elimination Programme (NMEP) aims to eliminate malaria by 2030 under the National Center for Vector Borne Diseases Control (NCVBDC). WHO has approved RTS, S/AS01 (Mosquirix) vaccine for children. B is matched with 3: Polio is caused by the poliovirus (genus Enterovirus) which spreads via contaminated food, water, or contact. Widely available vaccines (OPV and IPV) prevent polio. India’s Pulse Polio Programme launched in 1995 achieved polio-free certification in 2014. C is matched with 2: Tuberculosis is caused by Mycobacterium tuberculosis. It primarily affects the lungs and spreads through the air. The BCG vaccine provides TB prevention in children. India’s National Tuberculosis Elimination Programme (NTEP) offers free treatment and nutrition support under Nikshay Poshan Yojana, aiming for elimination by 2025. D is matched with 1: Ringworm is a fungal infection caused by dermatophytes such as Trichophyton, Microsporum, or Epidermophyton. It affects the skin, hair, or nails, spreading through direct skin contact or contaminated surfaces.
Haemophilia is a genetic disorder where the blood does not clot properly due to a deficiency of clotting factors (such as Factor VIII in Haemophilia A or Factor IX in Haemophilia B). This leads to excessive bleeding even from minor injuries.
The pituitary gland, often termed the "master gland,” regulates various endocrine glands through its tropic hormones. The parathyroid gland regulates calcium and phosphate balance in the body via parathyroid hormone (PTH) and its activity is independent of pituitary gland control. It is self-regulating, depending directly on calcium levels in the blood. Options (a), (b), and (c) are incorrect: The thyroid, gonads, and adrenal glands are regulated by pituitary tropic hormones such as TSH (thyroid-stimulating hormone), LH/FSH (for gonads), and ACTH (adrenocorticotropic hormone) for the adrenal glands. These glands depend on the pituitary to regulate the production of key hormones that control metabolism, growth, and stress responses.
Oxygen transportation in the human body is essential for cellular respiration, which generates energy in the form of ATPs. This process ensures oxygen is delivered to tissues and carbon dioxide is removed efficiently. Oxygen enters the body through the lungs (2), binds to hemoglobin in the blood (1), and is transported to the tissues (3) where it is utilized for energy production. This sequence reflects the physiological process of oxygen transport.
Option (b) is correct: The corpus luteum is a temporary endocrine structure found in the ovary formed after ovulation. It produces progesterone, which is critical for maintaining the uterine lining and supporting pregnancy in the early stages. Options (a), (c), and (d) are incorrect: The corpus luteum is specific to the ovary and is unrelated to the brain, pancreas, or spleen.
Alpha-keratin is a fibrous structural protein that forms the primary component of the skin, hair, nails, horns, and hooves in mammals. It belongs to the keratin family of proteins and is rich in disulfide bonds, which provide strength, durability, and elasticity to epithelial cells. In the skin, alpha-keratin creates a protective barrier against physical damage, dehydration, and pathogens. In hair and nails, it contributes to their hardness and resistance to wear. Options (a), (c), and (d) are incorrect: Alpha-keratin is not found in blood, lymph, or eggs. These tissues have other proteins like hemoglobin (in blood) or albumin (in eggs).
Option (a) is correct: The average fat content of buffalo milk is approximately 7.2%, significantly higher than that of cow>s milk. Buffalo milk is richer in fat compared to cow>s milk, which typically contains around 3-4% fat. The higher fat content in buffalo milk contributes to its creamy texture and makes it ideal for producing dairy products like butter, ghee, and cheese. Options (b), (c), and (d) are incorrect: 4.5% is typical of cow’s milk, while 9.0% and 10.0% are not average values for buffalo milk.
Option (d) is correct: Fructose is the major component of honey making up about 38-40% of its composition. It is a monosaccharide and is sweeter than glucose. The high fructose content is responsible for honey>s sweetness and its resistance to crystallization compared to glucose. Options (a), (b), and (c) are incorrect:
Glucose is one of the primary sugars found in honey, but it is not the major component. Honey typically contains about 30-35% glucose. Glucose is a monosaccharide and contributes to the sweetness and crystallization of honey. Sucrose is a disaccharide composed of glucose and fructose. While it is present in honey, it is found in very small amounts (usually less than 5%). Most of the sucrose in nectar is broken down into glucose and fructose by enzymes during the honey-making process. Maltose is not a significant sugar in honey. It is also known as maltobiose or malt sugar which is a disaccharide formed from two units of glucose joined with an -bond between the glucose units.
| Q | UPSC year | Correct answer |
|---|---|---|
| 91 | 1998 | (a) Aerobic respiration |
| 92 | 1998 | (a) polyunsaturated fatty acids |
| 93 | 1998 | (a) A-4; B-3; C-2; D-1 |
| 94 | 1998 | (d) non-clotting of blood |
| 95 | 1997 | (d) Parathyroid |
| 96 | 1997 | (c) 2, 1, 3 |
| 97 | 1997 | (b) Ovary |
| 98 | 1997 | (b) Skin |
| 99 | 1997 | (a) 7.2% |
| 100 | 1997 | (d) fructose |
This page covers 116 previous year UPSC Prelims GS Paper-I questions on Biology: Zoology (Science and Technology), asked from 1996 to 2025. Each has the correct answer and an explanation.
A bat. The flying fox is a large fruit bat, a mammal that flies using wings of skin, not a bird, and it is found across India and South Asia.
The gene is on the X chromosome. A carrier mother can pass the gene to her son, who has only one X chromosome and no second copy to compensate, so he shows the condition.
A mammal. The Dugong is a marine mammal, a herbivore that feeds on seagrass, and it is vulnerable to extinction. It is found in the Gulf of Mannar and around the Andaman and Nicobar Islands.
