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Q1Science·General Science Mixed ConceptsPYQ 2023
Some microorganisms can grow in environments with temperature above the boiling point of water. Some can grow below the freezing point of water. Some can grow in highly acidic environments with a pH below 3.
How many of the above statements are correct?
- AOnly one
- BOnly two
- CAll threeCorrect
- DNone
Explanation
Correct. Thermophiles thrive above 100 °C near hydrothermal vents, psychrophiles grow below 0 °C in polar ice, and acidophiles flourish at pH below 3 in acid mine drainage.
Why the other options are incorrect
- Option A
All three statements are correct; thermophiles, psychrophiles and acidophiles are well-documented extremophiles.
- Option B
All three statements describe real categories of extremophilic microorganisms, not just two.
- Option D
Extremophiles capable of surviving each of these conditions have been extensively documented.
Q2Science·General Science Mixed ConceptsPYQ 2022
Consider the following statements in respect of probiotics:
1. Probiotics are made of both bacteria and yeast.
2. The organisms in probiotics are found in foods we ingest but they do not naturally occur in our gut.
3. Probiotics help in the digestion of milk sugars.
Which of the statements given above is/are correct?
- A1 only
- B2 only
- C1 and 3Correct
- D2 and 3
Explanation
Correct. Probiotics include both bacteria (e.g., Lactobacillus) and yeast (e.g., Saccharomyces boulardii), and they aid in digesting lactose. Statement 2 is wrong because probiotic organisms naturally inhabit the gut.
Why the other options are incorrect
- Option A
Statement 3 is also correct; probiotic bacteria such as Lactobacillus produce lactase that helps digest lactose.
- Option B
Statement 2 is incorrect because probiotic organisms do naturally occur in the human gut; also statement 1 is correct.
- Option D
Statement 2 is incorrect; many probiotic species are part of the natural gut microbiome.
Q3Science·General Science Mixed ConceptsPYQ 2021
Consider the following:
1. Bacteria
2. Fungi
3. Virus
Which of the above can be cultured in an artificial/synthetic medium?
- A1 and 2 onlyCorrect
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3
Explanation
Correct. Bacteria and fungi can be grown on synthetic nutrient media. Viruses are obligate intracellular parasites and require living host cells, so they cannot be cultured on artificial media alone.
Why the other options are incorrect
- Option B
Viruses cannot be cultured on artificial media; they need living host cells to replicate.
- Option C
Viruses are obligate intracellular parasites and cannot grow on synthetic media.
- Option D
Viruses lack the cellular machinery for independent replication and must infect host cells.
Q4Science·General Science Mixed ConceptsPYQ 2021
In the nature, which of the following is/are most likely to be found surviving on a bare rock?
1. Fern
2. Lichen
3. Moss
4. Mushroom
Select the correct answer using the code given below.
- A1 and 4 only
- B2 only
- C2 and 3Correct
- D1, 3 and 4
Explanation
Correct. Lichens and mosses are pioneer species capable of colonising bare rock. Lichens secrete acids that slowly weather rock, and mosses can anchor on minimal substrate.
Why the other options are incorrect
- Option A
Ferns need soil with organic matter and mushrooms need decaying substrate; neither are primary colonisers of bare rock.
- Option B
Mosses are also pioneer species that can colonise bare rock alongside lichens.
- Option D
Ferns and mushrooms require more developed soil and cannot typically survive on bare rock.
Q5Science·General Science Mixed ConceptsPYQ 2014
Among the following organisms, which one does not belong to the class of other three?
- ACrabCorrect
- BMite
- CScorpion
- DSpider
Explanation
Correct. Mites, scorpions and spiders are all arachnids (class Arachnida), whereas crabs belong to the class Malacostraca (crustaceans).
Why the other options are incorrect
- Option B
Mites are arachnids, the same class as scorpions and spiders.
- Option C
Scorpions belong to class Arachnida along with mites and spiders.
- Option D
Spiders are arachnids, grouped with mites and scorpions.
Q6Science·General Science Mixed ConceptsPYQ 2013
Consider the following minerals:
1. Calcium
2. Iron
3. Sodium
Which of the minerals given above is/are required by the human body for the contraction of muscles?
- A1 only
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3Correct
Explanation
Correct. Calcium triggers the actin-myosin interaction for contraction, sodium enables nerve impulse transmission to muscles, and iron is vital for oxygen delivery to muscle tissue via haemoglobin.
Why the other options are incorrect
- Option A
Iron and sodium are also needed for proper muscle function.
- Option B
Calcium is essential for triggering muscle contraction through calcium-troponin interaction.
- Option C
Iron is required for oxygen transport via haemoglobin and myoglobin, which is essential for muscle function.
Q7Science·General Science Mixed ConceptsPYQ 2013
Consider the following animals:
1. Sea cow
2. Sea horse
3. Sea lion
Which of the above is/are mammal/mammals?
- A1 only
- B1 and 3 onlyCorrect
- C2 and 3 only
- D1, 2 and 3
Explanation
Correct. Sea cows (dugongs/manatees) and sea lions are marine mammals. Sea horses are bony fish of the genus Hippocampus.
Why the other options are incorrect
- Option A
Sea lions are also mammals; they belong to the order Carnivora, family Otariidae.
- Option C
Sea horses are fish, not mammals; they breathe through gills.
- Option D
Sea horses are ray-finned fish and do not qualify as mammals.
Q8Science·General Science Mixed ConceptsPYQ 2010
From the point of view of evolution of living organisms, which one of the following is the correct sequence of evolution?
- AOtter — Tortoise — Shark
- BShark — Tortoise — OtterCorrect
- CTortoise — Shark — Otter
- DShark — Otter — Tortoise
Explanation
Correct. Fish (shark) evolved first, followed by reptiles (tortoise), and then mammals (otter) — matching the progression of vertebrate evolution.
Why the other options are incorrect
- Option A
This reverses the evolutionary sequence; fish evolved before reptiles, which evolved before mammals.
- Option C
Sharks (cartilaginous fish) appeared in the fossil record before reptiles like tortoises.
- Option D
Mammals evolved after reptiles, not before them.
Q9Science·General Science Mixed ConceptsPYQ 2008
Assertion (A): In the human body, the liver has an important role in fat digestion.
Reason (R): Liver produces two important fat-digesting enzymes.
Select the correct answer.
- ABoth A and R are individually true and R is the correct explanation of A
- BBoth A and R are individually true but R is not the correct explanation of A
- CA is true but R is falseCorrect
- DA is false but R is true
Explanation
Correct. The liver aids fat digestion by producing bile which emulsifies fats, making A true. However, the liver does not produce fat-digesting enzymes (lipases come from the pancreas), making R false.
Why the other options are incorrect
- Option A
R is incorrect because the liver does not produce fat-digesting enzymes; it produces bile salts which emulsify fats.
- Option B
R is factually wrong; bile is not an enzyme.
- Option D
The assertion is true; the liver does play a role in fat digestion through bile production.
Q10Science·General Science Mixed ConceptsPYQ 2007
How do most insects respire?
- AThrough skin
- BThrough gills
- CBy lungs
- DBy tracheal systemCorrect
Explanation
Correct. Insects respire through a network of tracheae — tiny tubes that open at spiracles on the body surface and deliver oxygen directly to tissues.
Why the other options are incorrect
- Option A
Cutaneous respiration is characteristic of some amphibians, not insects.
- Option B
Gills are used by aquatic organisms like fish and some larval insects, not adult insects generally.
- Option C
Lungs are characteristic of vertebrates such as mammals, birds and reptiles, not insects.
Q11Science·General Science Mixed ConceptsPYQ 2007
Which one of the following is the correct sequence in the order of decreasing length of the three structural parts of the small intestine in the human body?
- AJejunum — Duodenum — Ileum
- BIleum — Duodenum — Jejunum
- CIleum — Jejunum — DuodenumCorrect
- DJejunum — Ileum — Duodenum
Explanation
Correct. The ileum (~3.5 m) is the longest, followed by the jejunum (~2.5 m), and the duodenum (~25 cm) is the shortest part of the small intestine.
Why the other options are incorrect
- Option A
The duodenum is the shortest segment, not intermediate; and the ileum is the longest.
- Option B
The duodenum is the shortest, not the second longest.
- Option D
The ileum is longer than the jejunum, so this order is incorrect.
Q12Science·General Science Mixed ConceptsPYQ 2007
In human beings, normally in which one of the following parts does the sperm fertilize the ovum?
- ACervix
- BFallopian tubeCorrect
- CLower part of uterus
- DUpper part of uterus
Explanation
Correct. Fertilization typically occurs in the ampulla of the fallopian tube (oviduct), where the sperm meets the ovum after ovulation.
Why the other options are incorrect
- Option A
The cervix is the passage between the vagina and uterus; fertilization does not normally occur here.
- Option C
The uterus is where the fertilized egg implants, but fertilization itself happens in the fallopian tube.
- Option D
The upper uterus receives the embryo for implantation, but the actual union of sperm and egg occurs in the oviduct.