Why do plants and animals need nitrogen

Where is the energy wasted in the system, and explain how

What is the purpose of a membrane on the mitochondria?

There is a population of bear that has declined. New neighborhoods are being build, as such the bear no longer have a place to live. WHich type of limiting factor is this situation?

Explain how the passage of food through the digestive tract is regulated

Which best describes the theory of evolution? A. a theory supported by evidence B. an educated guess C. a hunch made by scientists D. a hypothesis with no evidence

Since mature red blood cells do not contain a nucleus, more room is available for what?

What does a cladogram show about organisms?

What is the most efficient enzyme known that can catalyze hydrogen?

The process where sediments turn into a sedimentary rock through compaction or cementation is called

Muscles in animals are often found in pairs, because A. muscles need to be able to both push and pull. B. muscles can only push. C. muscles can only produce a force as they relax. D. muscles can only pull.