General Science MCQ Practice

Correct option: A

• Why correct: Fibrinogen is the plasma protein that is converted into fibrin by thrombin, forming a mesh that clots blood.
• Key concept: Blood coagulation cascade; fibrin formation seals wounds.
• Brief formula/logical note: Fibrinogen --thrombin→ Fibrin (clot).
• Exam tip: If asked about clotting, think fibrinogen → fibrin, not Hb, glucose, or cells.
• Why others are incorrect: Haemoglobin carries oxygen, glucose is an energy sugar, and blood cells themselves are not the clotting protein.

• Key concept: Not all infectious diseases are caused by bacteria. Some are due to parasites or protozoa.
• Correct answer: B. Malaria and trichomoniasis are caused by a protozoan parasites (Plasmodium; Trichomonas vaginalis), not bacteria.
• Why others are incorrect:

Answer: C. Carbon tetrachloride

• Why correct: Pyrene was a trade name for carbon tetrachloride, an extinguishing agent that cools and disrupts the chemical reactions in flame, helping to stop combustion.
• Key concept: Fire suppression by chemical inhibition of radical reactions and cooling.
• Other options: - A) CO2 is used in extinguishers but not linked to Pyrene. - B) Chloroform and D) bleaching powder are not extinguishing agents for fires.
• Exam tip: Remember common extinguishing agents: CO2, H2O, dry chemical; avoid toxic CCl4 references in safety contexts.

The correct option is B. Trichology.

• Why correct: Trichology is the branch of dermatology that studies hair and scalp, including diseases and disorders.
• Key concept: The root "tricho-" means hair in Greek.
• Other options:
  • A/C Penology — study of punishment and prisons.
  • D Pomology — study of fruits.
• Exam tip: Remember "tricho" = hair.

• Correct answer: A — Fractional distillation
• Why: Crude oil is heated and its mixture is passed up a fractionating column; components with different boiling points vaporize and condense at different heights, giving gasoline in a specific boiling-range fraction.
• Key concept: Boiling-point separation of mixtures; fractional distillation separates by boiling range, not by evaporation alone.
• Misleading options: Sublimation and simple evaporation do not separate crude oil into useful fuel fractions; (B) is the same as (A) but redundancy, others are incorrect.
• Exam tip: Remember gasoline corresponds to mid-range distillation fractions (roughly 40–200°C depending on refinery).

Answer: D) Garber method

• The Garber (Gerber) method is a volumetric technique to determine milk fat by separating fat in a butyrometer after acid digestion; fat volume is read directly and converted to % fat.
• Key concept: fat forms a distinct layer whose volume correlates with fat content. A simple conversion factor relates mL of fat to percentage fat.
• Formula/numerical note: % fat ≈ (fat volume in mL) × factor (from calibration).
• Exam tip: distinguish from Soxhlet (solvent extraction) and other methods; Garber is the standard volumetric method for milk fat.
• Why others are incorrect: A, C—not volumetric fat determination; B—Soxhlet is gravimetric, not volumetric.

Explanation

• Correct option: B — Thiamine deficiency is a lack of vitamin B1, known as beriberi.
• Key concept: Thiamine is a coenzyme (thiamine pyrophosphate) essential for carbohydrate metabolism and energy production in cells.
• Why others are incorrect: A is wrong (vitamin K helps blood clotting); C is wrong (vitamin C prevents scurvy); D is wrong (nicotine is a stimulant, not a vitamin).

Exam tip: If a question mentions beriberi, think vitamin B1 and carbohydrate metabolism.

Explanation:

• Correct: A. Photosynthesis is the process by which plants trap light energy to convert carbon dioxide and water into glucose (food).
• Key concept: Chlorophyll captures light; energy drives chemical reactions (CO2 + H2O → C6H12O6 + O2).
• Formula cue: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
• Exam tip: If the question asks “how plants make food,” choose photosynthesis first.
• Why others are incorrect: Carbohydrolysis, metabolic synthesis, and photorespiration are not the food-producing process in plants.

Question: Which of the following animals is carnivorous?

• Correct option: D
• Answer: Tiger

Explanation: Carnivores eat meat. Tigers are obligate carnivores, with sharp teeth and claws for hunting. The key scientific concept is dietary classification: herbivore (plants), carnivore (meat), or omnivore (both). Why others are incorrect: Elephants, horses, and rhinoceroses are herbivores or primarily plant-eaters. Exam tip: Remember: large canines and sharp claws often signal carnivory in mammals. Formula/logic: Carnivore ≈ meat-based diet.