q: Male dogs use what in their urine to mark their territory?
Options:
- (A) hydrocarbons
- (B) volatile substances
- (C) kinetic energy
- (D) an area swollen with pus
- (E) Chemical energy
- (F) competing for resources
- (G) add a solute
- (H) Positive charges
a: (B)... Explanation: Male dogs use pheromones in urine to mark their territory. Generally, pheromones are volatile substances. Male dogs use volatile substances in urine to mark their territory. That's why the answer is (B).

q: What uses food for energy?
Options:
- (A) Most plants
- (B) no organisms
- (C) agriculture
- (D) the Moon
- (E) animals
- (F) athletes
- (G) most organisms
- (H) the Sun
a: (G)... Explanation: Glucose is used for energy by the cells of most organisms. Food is converted into glucose. Food is used for energy by most organisms. That's why the answer is (G).

q: What enables bones to perform movement?
Options:
- (A) contraction
- (B) Energy
- (C) sensory neurons
- (D) looseness
- (E) Chemical energy
- (F) Vibrates
- (G) fur and fat
- (H) layers of fat
a: (A)... Explanation: Muscles can only contract. Bones work with muscles to perform movement. Contraction enables bones to perform movement. That's why the answer is (A).

q: Most ecosystems get energy from what in the atmosphere?
Options:
- (A) fires
- (B) Sun
- (C) wind
- (D) summer
- (E) oxygen
- (F) Light
- (G) heat
- (H) H20
a:
(G)... Explanation: Most ecosystems get energy from sunlight. On Earth, energy from sunlight heats the atmosphere more at the equator than at the poles. Most ecosystems get energy from heat in the atmosphere. That's why the answer is (G).