Question

hydrothermal vents are located
a) in shallow ocean waters
b) on mountain tops
c) on the deep ocean floor
d) in underground caves
what was notably absent from earths early atmosphere?
a) methane
b) oxygen
c) ammonia
d) toxic gases
organisms that get energy from chemicals instead of sunlight are called
a) phototrophs
b) chemotrophs
c) cyanobacteria
d) stromatolites

Explanation:

Hydrothermal vents are found on the deep - ocean floor where hot water rich in minerals gushes out. Earth's early atmosphere had little to no free - oxygen as there were no significant oxygen - producing organisms like plants at that time. Chemotrophs are organisms that obtain energy from chemicals rather than sunlight.

Answer:

1. c) On the deep ocean floor
2. b) Oxygen
3. b) Chemotrophs