Question

in 1977, a soviet research vessel deployed the mir-1 submersible to investigate lake baikal’s hydrothermal vents, located more than a kilometer below the surface. the team documented mineral chimneys composed primarily of barite and silica, structures that supported dense colonies of a very rare type of life: chemoautotrophic bacteria deriving energy from hydrogen sulfide rather than sunlight. because these microbial communities thrived in an isolated, oxygen - poor environment, they offered a rare analogue for hypothesizing life’s potential adaptations on icy moons such as europa.
6
mark for review
what is the main purpose of the text?
a to argue that lake baikal’s vent systems directly confirm the presence of similar ecosystems beyond earth.
b to emphasize the role of hydrothermal mineral deposits in shaping the chemical composition of the lake’s overall food web.
c to describe an effort that found a group of uncommon life forms whose energy sources inform theories about extraterrestrial life.
d to present the mir - 1 mission as the first instance of using submersible technology to explore aquatic bacterial colonies.

Explanation:

• Option A: The text doesn't argue that Lake Baikal's vents confirm ecosystems beyond Earth, but uses the life there to hypothesize about extraterrestrial life adaptations, so A is incorrect.
• Option B: The text's focus isn't on the role of hydrothermal deposits in the lake's food web, but on the microbial communities and their relevance to extraterrestrial life theories, so B is incorrect.
• Option C: The text describes the MIR - 1 mission's discovery of rare chemoautotrophic bacteria (uncommon life forms) and how their energy source (from hydrogen sulfide) informs theories about life on icy moons (extraterrestrial life), which matches this option.
• Option D: The text doesn't claim the MIR - 1 mission was the first to use submersible tech for aquatic bacterial colonies exploration, so D is incorrect.

Answer:

C. To describe an effort that found a group of uncommon life forms whose energy sources inform theories about extraterrestrial life.