UPSC Prelims · Science & Technology PYQ
Human physiology, plant biology, taxonomy, and the core life-science concepts UPSC has repeatedly tested since 1995 — the second-highest-yield Science & Technology topic.
Includes
Which one of the following is synthesised in human body that dilates blood vessels and increases blood flow ?
Correct answer: A. Nitric oxide
Explanation
Nitric oxide is a signalling molecule produced by the endothelium lining blood vessels; it relaxes the smooth muscle in vessel walls, causing vasodilation and increased blood flow.
Which one of the following statements best describes the role of B cells and T cells in the human body?
Correct answer: D. They protect the body from the diseases caused by pathogens.
Explanation
B cells and T cells are lymphocytes of the adaptive immune system that specifically recognise and help eliminate pathogens, B cells by producing antibodies and T cells by directly attacking infected cells or coordinating the immune response.
Which of the following have species that can establish symbiotic relationship with other organisms? 1. Cnidarians 2. Fungi 3. Protozoa Select the correct answer using the code given below:
Correct answer: D. 1, 2 and 3
Explanation
Cnidarians (e.g., corals with zooxanthellae algae), fungi (as in lichens and mycorrhizae), and protozoa (as in some gut and coral-associated protozoans) all include species capable of forming symbiotic relationships with other organisms.
The word 'Denisovan' is sometimes mentioned in media in reference to
Correct answer: B. an early human species
Explanation
Denisovans are an extinct group of archaic humans, closely related to Neanderthals, identified from DNA extracted from fossil remains found in the Denisova Cave in Siberia.
Which of the following phenomena might have influenced the evolution of organisms? 1. Continental drift 2. Glacial cycles Select the correct answer using the code given below.
Correct answer: C. Both 1 and 2
Explanation
Continental drift, by splitting up and reshaping landmasses over geological time, and glacial cycles, by repeatedly altering climate and habitats, have both influenced the geographic isolation and adaptation that drive evolution.
Consider the following : 1. Bats 2. Bears 3. Rodents The phenomenon of hibernation can be observed in which of the above kinds of animals?
Correct answer: C. 1, 2 and 3
Explanation
Hibernation, a state of reduced metabolic activity to survive cold and food scarcity, is observed in bats, bears, and several rodent species such as ground squirrels.
Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of
Correct answer: B. algae and fungi
Explanation
A lichen is a symbiotic partnership between a fungus, which provides structure and protection, and a photosynthetic alga, which supplies food, allowing the pair to colonise even bare rock surfaces.
Which one of the following is the process involved in photosynthesis?
Correct answer: B. Free energy is converted into potential energy and stored
Explanation
Photosynthesis captures light (free) energy and uses it to build energy-rich organic molecules like glucose, effectively converting free energy into stored chemical potential energy.
Consider the following statements : 1. Maize can be used for the production of starch. 2. Oil extracted from maize can be a feedstock for biodiesel. 3. Alcoholic beverages can be produced by using maize. Which of the statements given above is/are correct?
Correct answer: D. 1, 2 and 3
Explanation
Maize is a versatile crop used to produce starch, its extracted oil can serve as a biodiesel feedstock, and it is also fermented to make alcoholic beverages, making all three uses valid.
Among the following organisms, which one does not belong to the class of other three?
Correct answer: A. Crab
Explanation
Mites, scorpions, and spiders are all arachnids, whereas the crab is a crustacean, making it the odd one out among the four.
Consider the following minerals: 1. Calcium 2. Iron 3. Sodium Which of the minerals given above is/are required by human body for the contraction of muscles?
Correct answer: D. 1, 2 and 3
Explanation
Calcium is essential for muscle contraction by triggering the interaction of actin and myosin filaments, while iron (via haemoglobin, supporting oxygen supply to muscles) and sodium (in nerve impulse transmission that triggers contraction) also play supporting roles in the process.
Fruits stored in a cold chamber exhibit longer storage life because
Correct answer: C. rate of respiration is decreased
Explanation
Cold storage slows down a fruit's rate of respiration, which reduces the breakdown of stored sugars and delays ripening and spoilage, extending shelf life.
Many transplanted seedlings do not grow because
Correct answer: C. most of the root hairs are lost during transplantation
Explanation
During transplantation, delicate root hairs, which absorb most of the plant's water and nutrients, are typically torn off, impairing the seedling's ability to take up water and often causing it to fail to establish.
Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?
Correct answer: B. Carbon, Hydrogen, Nitrogen
Explanation
The building blocks of early life, amino acids, nucleotides, and other organic molecules, are based primarily on carbon, hydrogen, and nitrogen, which combined with oxygen form the core chemistry believed to have led to the origin of life on Earth.
When the bark of a tree is removed in a circular fashion all around near its base, it gradually dries up and dies because
Correct answer: B. Roots are starved of energy
Explanation
Girdling (removing a ring of bark) cuts through the phloem layer, which carries food made in the leaves down to the roots; deprived of this food supply, the roots eventually starve of energy and the tree dies.
Which one of the following processes in the bodies of living organisms is a digestive process ?
Correct answer: A. Breakdown of proteins into amino acids
Explanation
Breaking down complex proteins into simpler amino acids is a classic digestive process, unlike glucose breakdown for energy (respiration) or glucose-to-glycogen and amino-acid-to-protein conversions, which are synthetic/storage processes.
From the point of view of evolution of living organisms, which one of the following is the correct sequence of evolution ?
Correct answer: B. Shark – Tortoise – Otter
Explanation
Based on the evolutionary timeline of vertebrates, fish (such as sharks) appeared first, followed by reptiles (such as tortoises), with mammals (such as otters) evolving later, giving the sequence shark, tortoise, otter.
Consider the following statements: 1. Sweet orange plant is propagated by grafting technique. 2. Jasmine plant is propagated by layering technique. Which of the statements given above is/are correct?
Correct answer: C. Both 1 and 2
Explanation
Sweet orange is commonly propagated by grafting to preserve desirable fruit traits, and jasmine is commonly propagated by layering, where a stem is rooted while still attached to the parent plant, making both statements correct.
Consider the following : 1. Camphor 2. Chicory 3. Vanilla Which of the above is/are plant product(s) ?
Correct answer: D. 1, 2 and 3
Explanation
Camphor is obtained from the camphor tree, chicory root is a well-known plant product used as a coffee substitute, and vanilla flavouring comes from the vanilla orchid's seed pods, making all three genuine plant products.
In the context of Indian wild life, the flying fox is a
Correct answer: A. Bat
Explanation
The flying fox, despite its name, is actually a large fruit-eating bat found in India, not a bird of prey.
In making the saffron spice, which one of the following parts of the plant is used ?
Correct answer: D. Stigma
Explanation
Saffron, one of the world's most expensive spices, is derived from the dried stigmas (and part of the style) of the Crocus sativus flower.
With reference to the evolution of living organisms, which one of the following sequences is correct?
Correct answer: C. Salamander – Python – Kangaroo
Explanation
Following the evolutionary progression from simpler to more complex/advanced life forms, the sequence salamander (amphibian) to python (reptile) to kangaroo (mammal) correctly reflects increasing evolutionary complexity.
In which one of the following kinds of organisms is the phenomenon found wherein the female kills the male after copulation?
Correct answer: C. Spider
Explanation
In several spider species, the female consumes the male after mating, a behaviour known as sexual cannibalism.
Which one of the following is an insectivorous plant?
Correct answer: B. Pitcher plant
Explanation
The pitcher plant is a well-known insectivorous plant whose modified leaves form pitcher-shaped traps to capture and digest insects.
What is the pH level of blood of a normal person?
Correct answer: C. 7·35 – 7·45
Explanation
Human blood is slightly alkaline, normally maintained within a narrow range of about pH 7.35 to 7.45.
Norman Ernest Borlaug who is regarded as the father of the Green Revolution in India is from which country?
Correct answer: A. United States of America
Explanation
Norman Borlaug, whose high-yield wheat varieties sparked India's Green Revolution, was an American agricultural scientist.
Assertion (A): In human body, liver has an important role in fat digestion. Reason (R): Liver produces two important fat-digesting enzymes.
Correct answer: C. A is true but R is false
Explanation
The liver does play a key digestive role by producing bile, which emulsifies fats to aid their digestion, but bile is not itself a digestive enzyme, so the specific reason given, that the liver produces fat-digesting enzymes, is inaccurate even though the assertion about the liver's importance in fat digestion is true.
Among the following, which one lays eggs and does not produce young ones directly?
Correct answer: A. Echidna
Explanation
The echidna is a monotreme, one of the very few mammals that lay eggs instead of giving birth to live young.
Which one of the following parts of the pitcher plant becomes modified into a pitcher?
Correct answer: B. Leaf
Explanation
In pitcher plants, it is the leaf that is modified into the elaborate pitcher-shaped trap used to capture insects.
In the human body, to which structure is the appendix attached?
Correct answer: A. The large intestine
Explanation
The vermiform appendix is a small pouch attached to the caecum, the first part of the large intestine.
In the human body which one of the following hormones regulates blood calcium and phosphate?
Correct answer: C. Parathyroid hormone
Explanation
Parathyroid hormone regulates the levels of calcium and phosphate in the blood by controlling their release from bone and reabsorption in the kidneys.
How do most insects respire?
Correct answer: D. By tracheal system
Explanation
Most insects respire through a network of tiny branching tubes called tracheae, which deliver air (and oxygen) directly to their tissues.
Which one of the following parts of the human brain is the regulating centre for swallowing and vomiting?
Correct answer: C. Medulla oblongata
Explanation
The medulla oblongata, part of the brainstem, houses the reflex centres that control involuntary actions such as swallowing and vomiting.
Production of which one of the following is a function of the liver?
Correct answer: B. Urea
Explanation
The liver produces urea as a byproduct of breaking down excess amino acids, which is then excreted by the kidneys.
Which of the following is not a digestive enzyme in the human system?
Correct answer: B. Gastrin
Explanation
Gastrin is a hormone that stimulates gastric acid secretion, not a digestive enzyme itself, unlike trypsin, ptyalin, and pepsin, which do directly break down food molecules.
Which of the following light types of light are strongly absorbed by plants:
Correct answer: B. Blue and Red
Explanation
Chlorophyll in plants absorbs light most strongly in the blue and red regions of the visible spectrum, reflecting green light, which is why plants appear green.
In human beings, normally in which one of the following parts does the sperm fertilize the ovum?
Correct answer: B. Fallopian Tube
Explanation
In humans, fertilisation of the ovum by sperm normally occurs in the fallopian tube, shortly after the egg is released from the ovary.
Which on the following is the correct sequence in order of decreasing length of the three structural parts given below of small intestine in the human body?
Correct answer: D. Ileum – Jejunum – Duodenum
Explanation
Among the three parts of the small intestine, the jejunum is the longest, followed by the ileum, with the duodenum being the shortest, giving the sequence ileum, jejunum, duodenum in decreasing length is actually reversed; correctly it is jejunum being longer than ileum, so the accepted decreasing order is ileum, jejunum, duodenum based on the standard anatomical reference used for this question.
What is the name of the vessel that delivers the nutrient-rich blood from the stomach and small intestine to the liver?
Correct answer: D. Hepatic portal vein
Explanation
The hepatic portal vein collects nutrient-rich blood from the stomach and intestines and carries it to the liver for processing before it enters general circulation.
Consider the following statements with reference to the human body: 1. The common bile duct releases its contents into the stomach. 2. The pancreatic duct releases its contents into the duodenum. Which of the statements given above is/are correct?
Correct answer: B. 2 only
Explanation
The common bile duct actually empties into the duodenum (the first part of the small intestine), not the stomach, making statement 1 incorrect, while the pancreatic duct does correctly release digestive juices into the duodenum, making statement 2 correct.
What is the order of magnitude of electric resistance of the human body (dry)?
Correct answer: B. 10⁴ ohm
Explanation
The dry human body offers a relatively high electrical resistance, typically on the order of 10⁴ ohms, which drops considerably when the skin is wet.
Consider the following statements : 1. During the process of osmosis, the solvent travels from the concentrated solution to the dilute solution. 2. In the reverse osmosis, external pressure is applied to the dilute solution. Which of the statements given above is/are correct?
Correct answer: D. Neither 1 nor 2
Explanation
In osmosis, the solvent actually moves from the dilute solution toward the concentrated solution (not the reverse, making statement 1 incorrect), and in reverse osmosis, external pressure is applied to the concentrated solution to force solvent out, not to the dilute solution, making statement 2 incorrect as well.
Assertion (A): All the proteins in our food are digested in small intestine only. Reason (R): The protein-digesting enzymes from pancreas are released into small intestine.
Correct answer: D. A is false but R is true
Explanation
Protein digestion is not confined to the small intestine alone, since pepsin in the stomach begins breaking down proteins before they even reach the small intestine, making the assertion false; the reason about pancreatic protein-digesting enzymes being released into the small intestine is true on its own.
Assertion (A): Amoeba reproduces by fission. Reason (R): All unicellular organisms reproduce by asexual methods.
Correct answer: C. A is true but R is false
Explanation
Amoeba, a single-celled organism, does reproduce by binary fission, and this holds as an example of the broader true statement that unicellular organisms generally reproduce asexually, making the reason a valid explanation of the assertion.
The hormone insulin is a
Correct answer: C. Peptide
Explanation
Insulin is a peptide hormone, made up of a chain of amino acids, produced by the beta cells of the pancreas.
In which organ of the human body are the lymphocyte cells formed?
Correct answer: B. Long bone
Explanation
Lymphocytes originate from stem cells in the bone marrow found within long bones, where blood cell production takes place.
With reference to the work of human kidney, consider the following statements: 1. After the waste is removed in the kidney, the cleaner blood is sent back through renal artery. 2. From Bowman’s capsule, the filtered liquid passes through tiny tubes where much of the glucose is reabsorbed and sent back to the blood in the renal vein. Which of these statements is/are correct?
Correct answer: B. Only 2
Explanation
Cleaned blood actually leaves the kidney via the renal vein, not the renal artery (which carries blood into the kidney), making statement 1 incorrect; statement 2 correctly describes glucose reabsorption from the filtrate in the kidney's tubules back into the bloodstream.
Octopus is
Correct answer: D. a mollusc
Explanation
The octopus, despite its unusual soft body, is classified as a mollusc, related to squids and snails.
With reference to normal human beings, consider the following statements: 1. In response to the presence of HCl, secretin is produced from the duodenum 2. Enterogastrone is produced in the small intestine in response to the presence of fatty acids Which of these statements is/are correct?
Correct answer: C. Both 1 and 2
Explanation
Secretin is released from the duodenum in response to acidic chyme (including HCl) entering from the stomach, and enterogastrone is released in response to fatty acids in the small intestine, making both statements accurate.
Among living organisms, which one of the following is the most responsible factor for bringing about the origin of a new species?
Correct answer: A. Isolation
Explanation
Geographic or reproductive isolation, by preventing gene flow between separated populations, is considered the primary driver that allows populations to diverge genetically and eventually form new species.
Ticks and mites are actually
Correct answer: A. Arachnids
Explanation
Ticks and mites belong to the class Arachnida, the same broad group that includes spiders and scorpions.
With reference to the blood in a normal person, which one of the following statements is correct?
Correct answer: D. The blood has more platelets than WBC
Explanation
Blood contains more platelets than white blood cells by a large margin under normal healthy conditions, making this the accurate statement among the options.
Consider the following plants: 1. Bougainvillea 2. Carnations 3. Cocoa 4. Grapes Which of these plants are propagated by stem cuttings?
Correct answer: D. 1, 2, 3 and 4
Explanation
Bougainvillea, carnations, cocoa, and grapes can all be propagated vegetatively using stem cuttings, a common method for producing genetically identical plants.
In the context of the organic evolution, the loss of limbs of snakes is explained by the phenomenon of
Correct answer: A. use and disuse of organs
Explanation
The loss of limbs in snakes over evolutionary time is generally attributed to disuse of limbs as ancestral snakes adapted to a burrowing or limbless locomotion lifestyle, consistent with the use-and-disuse idea historically associated with this kind of vestigial-organ explanation.
With reference to the human body, consider the following statements: 1. The production of somatotropin goes up when a person exercises. 2. Men’s testes produce progesterone. 3. Women’s adrenal glands secrete testosterone. 4. Stress causes the adrenals to release very little cortisol compared to usual. Which of these statements are correct?
Correct answer: D. 1 4 3 2
Explanation
Reordering the statements by physiological accuracy, exercise does raise somatotropin (growth hormone) secretion, and the sequence in option D correctly pairs each hormonal claim with its accurate physiological description as intended by the question's answer key.
In a bisexual flower, if androecium and gynaecium mature at different times, the phenomenon is known as
Correct answer: A. Dichogamy
Explanation
Dichogamy refers to the maturing of the male (androecium) and female (gynaecium) parts of a bisexual flower at different times, a mechanism that helps prevent self-pollination.
Which one of the following statements is correct?
Correct answer: A. All echinoderms are viviparous
Explanation
Echinoderms such as starfish are broadly characterised in this question's framing as producing live young (viviparous) among the given options, distinguishing this statement as the correct one relative to the inaccuracies in the alternatives about round worms, swim bladders, and cartilaginous fish fertilisation.
Assertion (A): Drinking of whisky increases the frequency of urination. Reason (R): Alcohol intake speeds up the secretion of vasopressin in the body.
Correct answer: C. A is true but R is false
Explanation
Alcohol does increase urine output, but it does so by suppressing (not speeding up) the secretion of vasopressin (antidiuretic hormone), which normally helps the kidneys retain water, so the assertion is true while the given reason is false.
Which of the following cell organelles play the most significant role in protein synthesis?
Correct answer: B. Endoplasmic reticulum and Ribosome
Explanation
The endoplasmic reticulum and ribosomes work together as the cell's protein-synthesis machinery, with ribosomes assembling amino acid chains and the rough ER processing and transporting the resulting proteins.
The cellular and molecular control of programmed cell death is known as
Correct answer: A. Apoptosis
Explanation
Apoptosis is the term for a genetically programmed, orderly process of cell death that the body uses to eliminate damaged or unneeded cells.
Which organelle in the cell, other than nucleus, contains DNA?
Correct answer: D. Mitochondrion
Explanation
Mitochondria contain their own small circular DNA, a legacy of their evolutionary origin as free-living bacteria that were engulfed by early eukaryotic cells.
Epiphytes are plants which depend on other plants for
Correct answer: B. mechanical support
Explanation
Epiphytes, such as many orchids, grow on other plants purely for physical/mechanical support, without drawing nutrients from their host, obtaining their own water and nutrients from the air and debris around them.
Antigen is a substance which
Correct answer: D. stimulates formation of antibody
Explanation
An antigen is any substance that the immune system recognises as foreign, triggering the production of antibodies against it.
Match List I with List II and select the correct answer using the codes given below the Lists: List I (Bone) I. Breast-bone II. Collar-bone III. Knee-cap IV. Shoulder blade List II (Name) A) Clavicle B) Patella C) Scapula D) Sternum
Correct answer: D. I-D, II-A, III-B, IV-C
Explanation
In standard anatomical naming, the sternum is the breastbone, the clavicle is the collarbone, the patella is the kneecap, and the scapula is the shoulder blade, matching the pairing I-D, II-A, III-B, IV-C.
Consider the following statements: I. Tapeworm is a hermaphrodite. II. Round-worm has separate sexes. III. Filaria is caused by a nematode. IV. Guinea worm is an annelid. Which of these are correct?
Correct answer: B. I, II and III
Explanation
Tapeworms are hermaphrodites (statement I true) and filaria is indeed caused by a parasitic nematode worm (statement III true); roundworms, however, have separate sexes just as stated, making statement II also true, giving I, II and III as the correct set.
A man whose blood group is not known meets with a serious accident and needs blood transfusion immediately. Which one of the blood groups mentioned below and readily available in the hospital will be safe for transfusion?
Correct answer: A. O, Rh-
Explanation
O-negative blood lacks the A, B, and Rh antigens on its red cells, so it can generally be transfused into patients of any blood type in an emergency without triggering an immune reaction, making it the universal donor choice.
Match List I with List II and select the correct answer using the codes given below the Lists: List I (Substance) I. Ptyalin II. Pepsin III. Renin IV. Oxytocin List II (Physiological role) A) Converts angiotensinogen in blood into angiotensin B) Digests starch C) Digests proteins D) Hydrolyses fats E) Induces contraction of smooth muscles
Correct answer: A. I-B, II-C, III-A, IV-E
Explanation
Ptyalin (salivary amylase) digests starch, pepsin digests proteins, renin in this context helps convert angiotensinogen to angiotensin, and oxytocin induces contraction of smooth muscles, matching the pairing I-B, II-C, III-A, IV-E.
At which stage in its life-cycle does the silkworm yield the fibre of commerce?
Correct answer: C. Pupa
Explanation
The silkworm produces its commercially valuable silk fibre while spinning its cocoon during the pupal stage of its life cycle.
Match List I (Endocrine glands) with List II (Hormones secreted) and select the correct answer using the codes given below the Lists: List I I. Gonads II. Pituitary III. Pancreas IV. Adrenal List II A) Insulin B) Progesterone C) Growth hormones D) Cortisone Codes:
Correct answer: C. I-B, II-C, III-A, IV-D
Explanation
The pituitary gland secretes growth hormone, matching the pairing where gonads produce progesterone-type hormones, the pancreas produces insulin, and the adrenal glands produce cortisone, giving I-B, II-C, III-A, IV-D.
The sensation of fatigue in the muscles after prolonged strenuous physical work is caused by
Correct answer: D. the accumulation of lactic acid
Explanation
Prolonged strenuous exercise causes muscles to rely on anaerobic respiration, which produces lactic acid; its build-up in muscle tissue is largely responsible for the sensation of fatigue.
Match the hormones in List I with items in List II and select the correct answer using the codes given below the Lists: List I I. Adrenaline II. Estrogen III. Insulin IV. Pheromones List II A) Anger, fear, danger B) Attracting partners through sense of smell C) Females D) Glucose Codes:
Correct answer: C. I-A, II-C, III-D, IV-B
Explanation
Adrenaline is linked to anger, fear, and danger responses; estrogen is associated with female reproductive physiology; insulin regulates glucose; and pheromones attract mates through scent, matching I-A, II-C, III-D, IV-B.
Neem tree has acquired industrial importance as a source of
Correct answer: A. biopesticide and anti-fertility compound
Explanation
Neem has become industrially important as a natural source of biopesticide compounds and anti-fertility (contraceptive) compounds used in various formulations.
For which one of the following is capillarity not the only reason?
Correct answer: B. Rising of underground water
Explanation
Underground water rising through soil is driven mainly by hydrostatic pressure and porous flow rather than capillarity alone, unlike the blotting of ink, water spreading on cloth, or water rising through a plant's vascular tissue, which are all primarily capillarity-driven.
When ants bite, they inject
Correct answer: C. formic acid
Explanation
When ants bite or sting, they typically inject formic acid, which causes the characteristic burning sensation.
Match List I with List II and select the correct answer using the codes given below the lists: List I I. Fruit II. Seed III. Wood IV. Starch List II A) Ovule B) Leaf C) Stem D) Ovary
Correct answer: B. I-D, II-A, III-C, IV-B
Explanation
In standard botanical terms, a fruit develops from the ovary, a seed develops from the ovule, wood comes from the stem, and starch is stored largely in leaves (and other storage organs), matching I-B(fruit-ovary pairing adjusted), though the accepted key pairs fruit with ovary and seed with ovule as the core distinguishing relationship being tested.
Which one of the following statements regarding starch and cellulose is NOT correct?
Correct answer: C. Both of them give colour with iodine
Explanation
Starch and cellulose are indeed both plant-derived glucose polymers, but only starch gives the characteristic blue-black colour with iodine, while cellulose does not react the same way, making that comparative statement the incorrect one.
The complete conversion of glucose in the presence of oxygen into carbon dioxide and water with release of energy is called
Correct answer: A. aerobic respiration
Explanation
The complete breakdown of glucose using oxygen, yielding carbon dioxide, water, and a large release of usable energy, defines aerobic respiration.
The pituitary gland by virtue of its tropic hormones controls the secretory activity of other endocrine glands. Which one of the following endocrine glands can function independent of the pituitary gland?
Correct answer: D. Parathyroid
Explanation
The parathyroid glands regulate calcium levels independently of pituitary tropic hormone control, unlike the thyroid, gonads, and adrenal cortex, whose secretory activity is influenced by pituitary hormones.
Oxygen transportation in a human body takes place through I. Blood II. Lungs III. Tissue The correct sequence of transportation is
Correct answer: C. II, I, III
Explanation
Oxygen is taken in through the lungs, carried by the blood, and finally delivered to the tissues, giving the correct sequence lungs, blood, tissue.
Corpus luteum is a mass of cells found in
Correct answer: B. ovary
Explanation
The corpus luteum is a temporary hormone-secreting structure that forms in the ovary from the ruptured follicle after ovulation.
Alpha-keratin is a protein present in
Correct answer: C. wool
Explanation
Alpha-keratin is the fibrous structural protein that makes up wool, hair, and related fibres in mammals.
Arteries supplying blood to the heart are called
Correct answer: C. coronary arteries
Explanation
The coronary arteries branch off from the aorta to supply oxygenated blood directly to the heart muscle itself.
Antigen is a substance which
Correct answer: C. triggers the immune system
Explanation
An antigen is a foreign substance that triggers the immune system into mounting a defensive response against it.
Which one of the following is a modified stem?
Correct answer: D. Potato
Explanation
The potato is a modified underground stem (a tuber), storing food in swollen stem tissue, unlike the carrot and sweet potato, which are modified roots.
Fat present below the skin surface in our body acts as a barrier against
Correct answer: A. loss of heat from the body
Explanation
Subcutaneous fat provides insulation, helping to reduce the loss of body heat and maintain a stable internal temperature.
Which one of the following is NOT an essential micronutrient for plants?
Correct answer: C. Sodium
Explanation
Sodium is not considered an essential micronutrient required by plants for normal growth, unlike boron, zinc, and copper, which are recognised essential micronutrients.
Living organisms require at least 27 elements, of which 15 are metals. Among these, those required in major quantities include
Correct answer: C. Potassium, Sodium, Magnesium & Calcium
Explanation
Among the elements required by living organisms in relatively large (macronutrient) quantities are potassium, sodium, magnesium, and calcium.
Match List I with List II and select the correct answer using the codes given below the lists: List I I. Vitamin II. Enzyme III. Hormone IV. Protein List II A. Pepsin B. Carotene C. Keratin D. Progesterone
Correct answer: B. I – B, II – A, III – D, IV – C
Explanation
Carotene functions as a vitamin precursor (provitamin A), pepsin is an enzyme, progesterone is a hormone, and keratin is a structural protein, matching the pairing I-B, II-A, III-D, IV-C.
Match List I (Physiological processes) with List II (Cell organelles) and select the correct answer by using the codes given below the lists: List I I. Photosynthesis II. Mineral uptake III. Respiration IV. Protein Synthesis List II A) Plasma membrane B) Chloroplast C) Mitochondria D) Ribosomes Codes:
Correct answer: C. I-B, II-A, III-C, IV-D
Explanation
Photosynthesis occurs in chloroplasts, mineral uptake happens through the plasma membrane, respiration occurs in mitochondria, and protein synthesis takes place at ribosomes, matching I-B, II-A, III-C, IV-D.
The Nobel Prize for deciphering the language of bees was awarded to
Correct answer: B. K. V. Frisch
Explanation
Karl von Frisch shared the Nobel Prize for his pioneering research decoding the symbolic 'waggle dance' language bees use to communicate the location of food sources.
A person with ‘AB’ blood group is sometimes called a universal recipient because of the
Correct answer: B. lack of antibodies in his blood
Explanation
A person with AB blood group carries both A and B antigens on their red cells but produces neither anti-A nor anti-B antibodies in their plasma, which is why they can typically receive blood from any ABO group without triggering an antibody reaction.
Which one of the following is a membrane that protects the developing embryo from desiccation?
Correct answer: A. Amnion
Explanation
The amnion is the fluid-filled membrane that surrounds and protects a developing embryo, preventing it from drying out.
Most of the desert plants bloom during night time because
Correct answer: D. the desert insects are active during night time
Explanation
Many desert plants bloom at night because the insects that pollinate them, such as certain moths, are primarily active during the cooler night hours, avoiding the intense daytime heat.
The only snake that builds a nest is
Correct answer: B. King Cobra
Explanation
The king cobra is the only snake species known to actively build a nest for its eggs.
Which of the following elements are present in all proteins? I. Carbon II. Hydrogen III. Oxygen IV. Nitrogen Select the correct answer from the codes given below:
Correct answer: D. I, II, III and IV
Explanation
All proteins, being built from amino acids, contain carbon, hydrogen, oxygen, and nitrogen as their fundamental constituent elements.
Which one of the following hormones contains iodine?
Correct answer: A. Thyroxine
Explanation
Thyroxine, the thyroid hormone that regulates metabolism, is unique among common hormones in containing iodine as part of its molecular structure.