Synechococcus, a cyanobacterium, is a free-living marine organism that fixes CO₂ into biomass while producing molecular oxygen utilized by swarms of heterotrophic bacteria. Which of the following is the most likely habitat of this bacterium?
A) euphotic zone of the pelagic environment
B) the benthos
C) the littoral zone
D) lake sediments
E) aphotic zone

Question

Quizplus · Accepted Answer

Synechococcus is a free-living marine organism, suggesting that it inhabits the pelagic environment rather than the benthos or lake sediments. It also fixes CO₂ and performs photosynthesis, which requires light, making the euphotic zone, where enough light penetrates for photosynthesis to occur, the most likely habitat for Synechococcus. The littoral zone is a transition zone between land and water, which may not support a large population of Synechococcus, while the aphotic zone lacks sufficient light for photosynthesis to occur.

Synechococcus, a Cyanobacterium, Is a Free-Living Marine Organism That Fixes