Biology: Zoology: UPSC Previous Year Questions (Science and Technology)
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 111–116 of 116 questions
Browse by year
UPSC 1996Science and Technology · Biology: Zoology
Q111. Consider the following statements. AIDS -is transmitted: 1. By sexual intercourse 2. By blood transfusion 3. By mosquitoes and other blood sucking insects 4. Across the placenta
Explanation
Option 1, 2 and 4 are correct: AIDS (Acquired Immunodeficiency Syndrome), caused by the HIV virus, is transmitted through:
Sexual intercourse: HIV is primarily transmitted through unprotected sexual contact, including vaginal and anal intercourse with an infected partner. The virus is present in bodily fluids such as semen and vaginal secretions. Blood transfusion: Receiving blood transfusions contaminated with HIV can transmit the virus. HIV can be transmitted from an infected mother to her child during pregnancy, childbirth, or breastfeeding. This mode of transmission is known as vertical or mother-to-child transmission. It is transferred from an infected mother to her foetus across the placenta. These are the primary modes of transmission as confirmed by WHO. Option 3 is incorrect: HIV cannot be transmitted through mosquitoes or other blood-sucking insects because the HIV virus does not survive or replicate in these organisms.
UPSC 1996Science and Technology · Biology: Zoology
Q112. Which of the following would lead to malnutrition? 1. Overnutrition 2. Undernutrition 3. Imbalanced nutrition Select the correct answer by using the codes given below: Codes:
Explanation
Malnutrition refers to a state of improper nutrition, which can arise from overnutrition (excess intake of food or nutrients), undernutrition (deficiency of essential nutrients), and imbalanced nutrition (inadequate or excessive intake of specific nutrients relative to others). Overnutrition: Consuming excessive calories or nutrients can lead to obesity and associated health issues like diabetes, cardiovascular diseases, and metabolic disorders. Undernutrition: A lack of essential nutrients causes deficiencies like protein-energy malnutrition (e.g., kwashiorkor, marasmus), anemia, and weakened immunity. Imbalanced nutrition: A diet lacking in proper proportions of macronutrients (carbohydrates, proteins, fats) and micronutrients (vitamins, minerals) can cause health problems, even if calorie intake is sufficient. All these conditions impair the body’s ability to function optimally and lead to health complications.
UPSC 1996Science and Technology · Biology: Zoology
Q113. People drinking water from a shallow hand pump, are likely to suffer from all of the following diseases except:
Explanation
Fluorosis results from prolonged excessive fluoride intake, leading to alterations in tooth enamel (dental fluorosis) or bone structure (skeletal fluorosis). It is commonly linked to water sources with high natural fluoride levels such as deep wells that access fluoride-rich geological formations. Since shallow hand pumps draw water from near the surface so they are less likely to contain such high fluoride concentrations. Options (a), (b), and (c) are incorrect:
Cholera, typhoid, and jaundice are caused by microbial or viral contamination of shallow water sources, making them common risks. These diseases are not linked to deep underground water. Cholera: A severe diarrheal disease caused by Vibrio cholerae, primarily spread through contaminated water and food. Typhoid: A bacterial infection caused by Salmonella typhi, characterized by high fever, weakness, and gastrointestinal symptoms. Jaundice: A condition marked by yellowing of the skin and eyes due to excess bilirubin, often caused by liver disease, hepatitis, or bile duct obstruction.
UPSC 1996Science and Technology · Biology: Zoology
Q114. Besides proteins and carbohydrates, other elements of nutritional value found in milk, include:
Explanation
Besides proteins and carbohydrates, milk is a rich source of calcium and potassium, which are essential for strong bones, teeth, and maintaining fluid balance. Calcium is essential for bone health, muscle function and nerve signaling. Potassium is an important electrolyte that helps regulate fluid balance, muscle contractions and nerve signals.
UPSC 1996Science and Technology · Biology: Zoology
Q115. Fat present below the skin surface in our body, acts as a barrier against:
Explanation
Subcutaneous fat is a layer of fat located just beneath the skin. It primarily acts as an insulator which reduces heat loss from the body by trapping heat and maintaining body temperature. This insulation is particularly beneficial in cold environments, helping to conserve energy and prevent hypothermia.
UPSC 1996Science and Technology · Biology: Zoology
Q116. The major chemical compound found in kidney stones is:
Explanation
Option (c) is correct: The major chemical compound that constitutes kidney stones is Calcium Oxalate. These stones are common and can cause severe pain during urination. Calcium oxalate is formed when calcium in the urine binds with oxalate, a compound found in certain foods (e.g., spinach, nuts) or produced as a by-product of metabolism. High concentrations of calcium and oxalate in urine, combined with low fluid intake, promote the crystallization of calcium oxalate. Options (a), (b), and (d) are incorrect: Urea is not a major component of kidney stones because it is a waste product of protein metabolism that is typically excreted in the urine. Other types of kidney stones can contain calcium carbonate, calcium phosphate, uric acid, or struvite, but calcium oxalate stones are the most common. Factors such as dehydration, high oxalate intake, and certain medical conditions can increase the risk of kidney stone formation.
Answer key for these questions
Q
UPSC year
Correct answer
111
1996
(b) 1, 2 and 4 are correct
112
1996
(d) 1, 2 and 3
113
1996
(d) Fluorosis
114
1996
(b) calcium and potassium
115
1996
(a) Loss of heat from the body
116
1996
(c) calcium oxalate
What UPSC has tested in Biology: Zoology
The flying fox is a bat; the Dugong is a mammal; the Panda belongs to the same family as the bear.
Certain species of ants are well known as cultivators of fungi.
Colour blindness is a sex-linked genetic disorder: a woman carrier can pass it to her son.
Resistance of the malarial parasite to drugs has prompted attempts to develop a vaccine.
Hepatitis B is several times more infectious than HIV.
Frequently asked questions
How many previous year UPSC questions are there on Biology: Zoology?
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.
Is a flying fox a bird or a bat?
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.
Why does colour blindness affect sons of carrier mothers?
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.
Is the Dugong a fish or a mammal?
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.
