General Science MCQ Practice

• Reason: A concave mirror can form a magnified (larger) image when the object is placed between the focal point (F) and the mirror. The magnification |m| > 1 in this region occurs because the image is real, inverted, and larger than the object.
• Key concept: Magnification m = hi/ho = -v/u. For large image, |v| > |u| in the F–to–mirror region.
• Other options: - Convex mirror (A) always gives smaller, virtual, upright images. - Plane mirror (C) gives same size image. - Plano-convex (D) can behave like a convex/concave surface depending on setup, but in standard use it does not reliably produce a larger image as a simple concave mirror does.
• Exam tip: Place object between F and the concave mirror to get a magnified real image.

• Correct answer: B — Agent Orange is a herbicide.
• It was a defoliant used to kill vegetation in forests and crops; its active components are auxin-like herbicides (2,4-D and 2,4,5-T).
• Key concept: herbicides destroy plant growth, not insects (insecticides) or nutrients (fertilisers).
• Formula/logic: not a nutrient; its effect is hormonal disruption in plants, leading to uncontrolled growth and death.
• Exam tip: remember “orange” defoliant = herbicide; never confuse with insecticides or fertilisers.
• Why others are incorrect: A insecticide targets insects; C fertiliser supplies nutrients; D biofertiliser contains living microbes.

• Key concept: Pathogenic parasites trigger the host’s immune system to produce antibodies.
• Why correct: “Pathogenic” means disease-causing; such parasites elicit an antibody response in the host.
• Other options:
  • Homoparasites: parasites of the same species, not a standard term for antibody induction.
  • Zooparasites: animal parasites, not specifically about antibody production.
  • Endoparasies: parasites living inside, not about immune response.

Exam tip: link “pathogenic” with disease and antibody response for quick recall.

• Why correct: Asbestos exposure is the well-established cause of mesothelioma.
• Why others are incorrect: Arsenic, Lead, and Mercury cause other toxicities (cancers at different sites, organ damage) but not mesothelioma.

• Intestinal (gut) bacteria synthesize vitamin K, mainly menaquinone, which aids blood clotting.
• Key concept: gut microbiota provide essential cofactors for the coagulation cascade, not required from diet alone.
• Why others are incorrect: Vitamins A, C, and D are not primarily produced by gut bacteria; they come from diet and sunlight (D) or are fat-soluble/dietary (A, C).
• Exam tip: Remember “K” stands for coagulation; gut bacteria help clotting factors.

• The cerebrum is the largest part of the human brain, forming the major bulk with two hemispheres and a folded cortex.
• It handles higher functions like thinking, learning, memory, voluntary movement, and perception.
• Key concept: brain parts have hierarchies in size; thalamus and pons are smaller, while the ribs are not part of the brain.
• Tip: Remember the letter “C” for Cerebrum as the largest brain region.
• Why others are incorrect: Thalamus and Pons are smaller brain structures; Ribs are part of the skeleton, not the brain.

• Reason: Sugarcane is a perennial grass in the family Poaceae. It has characteristics of grasses: hollow, jointed stems; long, slender leaves; and monocotyledonous seeds.
• Key concept: Belongs to grasses (Poaceae); all grasses are monocots with parallel leaf veins and fibrous root systems.
• Formula/numeric logic: Not needed here.
• Exam tip: If a plant has hollow stem and sheathes around a jointed stalk, classify as grass unless evidence shows a different family.
• Why others are incorrect: Creeper, shrub, and tree describe woody or sprawling forms, not typical of sugarcane’s grass-like habit.

• Reason: Common TV remotes use infrared (IR) light emitted by an LED and detected by an IR receiver. IR lies just beyond visible red light, not visible to humans.
• Key concept: Electromagnetic spectrum; line-of-sight communication with short-range, non-ionizing IR radiation.
• Tip: In exams, remember “Remote controls use infrared, not radio/microwave.”
• Why other options are incorrect:
  • A) Radio waves – typically for wireless data, not standard TV remotes.
  • B) Micro waves – used in microwave ovens and some communication, not remotes.
  • D) Ultrasonic waves – sound waves, not electromagnetic.