General Science MCQ Practice

• Why: A microscope uses convex (converging) lenses to collect and focus light, creating a magnified real or virtual image of the specimen.
• Key concept: Convex lenses converge rays to a focal point; the lens formula 1/f = 1/v − 1/u governs image formation.
• Tip: For magnification, use short focal length convex lenses in the objective.
• Why others are wrong: Concave lenses diverge rays (not suitable for high magnification); biconvex/biconcave options are not standard single-lens configurations for basic microscopes as given.

• Why: Cholera, Tuberculosis, and Typhoid are caused by bacteria. Smallpox is caused by Variola virus (not bacteria).
• Key concept: Disease causation depends on the pathogen type (bacteria vs. virus).
• Quick logic: If a disease is bacterial, antibiotics may help; viral diseases require different strategies (immune response, antivirals).
• Exam tip: Remember “smallpox is viral” to distinguish it from bacterial diseases.
• Incorrect options: A excludes Typhoid; B excludes Cholera and Smallpox; C excludes Typhoid.

• The threat of global warming rises with higher CO₂—a long‑lived greenhouse gas that traps infrared radiation in the lower atmosphere and at the surface.
• Key concept: Greenhouse effect—certain gases absorb heat re-radiated from Earth, warming the planet.
• Why others are less dominant: O₃, SO₂, NO₂ are pollutants and secondary effects; they are less persistent greenhouse gases compared to CO₂.

Exam tip: Remember CO₂ is the primary long‑lived greenhouse gas driving recent warming.

• Why correct: Barron is credited with conceptualizing and promoting the idea of an automated teller machine, laying the groundwork for modern ATMs.
• Key concept: Inventions often evolve from an idea prototype to a widely deployed system; early prototypes precede the commercial version.
• Other options:
  • A. Luther George Simjian – built an early prototype, but not the final concept widely adopted.
  • C. Douglas Brown – not associated with ATM invention.
  • D. None of these – incorrect since Barron is the credited figure here.
• Exam tip: Know the sequence: early prototype (Simjian) → conceptual idea (Barron) → modern ATM systems.

• Correct answer: A – Wrist
• Explanation: Carpal bones form the carpal (wrist) region, comprising eight small bones arranged in two rows. They connect the forearm to the hand and allow wrist movements.
• Key concept: Anatomy of the upper limb; carpal bones = wrist bones.
• Why others are wrong: Femur = thigh bone; Neck = part of the vertebral column or bone region; None of these = incorrect since wrist is correct.
• Exam tip: Remember “carpal” sounds like “carpenter’s” work at the wrist; helps recall location.

• Key concept: Genetic modification inserts or edits genes to give desired traits (pest resistance, yield, etc.).
• Why correct: Option B directly matches the standard definition used in science and policy.
• Other options: A and C are incorrect terms; D is false as GM is defined.

Exam tip: Remember common prefixes—“Genetically” indicates inheritance/change at the gene level, not traditional breeding.

• Correct answer: C Henri Becquerel discovered radioactivity in 1896 by observing spontaneous emission from uranium salts.
• Key concept: Radioactivity is the spontaneous emission of radiation from unstable atomic nuclei.
• Why others are incorrect: Marie Curie and Pierre Curie identified radioactive elements (polonium, radium) but did not discover the phenomenon. J J Thomson discovered the electron, not radioactivity.
• Tip: Remember Becquerel’s discovery preceded the Curie’s work on isolating radioactive elements.