The diatoms A) are a paraphyletic group. B) form cell walls containing CaCO₃. C) would likely be found in the deep ocean. D) are primary producers. E) are responsible for a small fraction of photosynthetic CO₂ fixation.

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Quizplus · Accepted Answer

The diatoms are primary producers, meaning that they are able to fix carbon through photosynthesis and form the base of many aquatic food webs. Answer: B Diatoms are known for their intricate silica cell walls, which contain the compound CaCO₃. Note: Option A is incorrect because recent genetic studies suggest that diatoms are a monophyletic group, meaning they share a common ancestor and all of its descendants. Option C is incorrect because while some diatoms may be found in the deep ocean, they can also be found in a variety of aquatic environments. Option E is incorrect because diatoms are responsible for a significant portion of photosynthetic carbon fixation in aquatic environments.

The Diatoms