Pea plants disperse their seeds through a mechanical “explosion” mechanism; when the pods dry out, they suddenly burst open with force, scattering the peas away from the parent plant.
42. Which of these forces makes an object come down on the surface of the earth?
(A) Gravity
(B) Friction
(C) Buoyancy
(D) Magnetism
Answer:
(A) Gravity
Explanation:
Gravity is the invisible physical force by which a planet or other body draws objects toward its center, keeping everything anchored to the ground.
43. Which of the following forms a layer of sediment in water?
(A) Sand
(B) Sugar
(C) Salt
(D) Oil
Answer:
(A) Sand
Explanation:
Sand particles are heavier and denser than water and are completely insoluble. Therefore, when mixed into water, they sink and form a layer of sediment at the bottom.
44. Disease spread from one person to another person is
(A) deficiency disease
(B) communicable disease
(C) non-communicable disease
(D) none of these
Answer:
(B) communicable disease
Explanation:
Diseases that can be transmitted from an infected person to a healthy person (via touch, air, bodily fluids, etc.) are known as infectious or communicable diseases.
45. Donating old toys and books is a way to _______ waste.
(A) reduce
(B) reuse
(C) dispose
(D) recycle
Answer:
(B) reuse
Explanation:
Donating items passes them on to others so they can be utilized again in their current form without requiring industrial reprocessing, which perfectly exemplifies “reusing” in waste management.
