Answer:
Explanation:Population genetics is the field of biology that studies allele frequencies in populations and how they change over time.
When an ecosystem has a scarce nutrient, that is when there is a nutrient limitation.
So the answer is C. <span>Nitrogen is typically the limiting nutrient in freshwater environments.
This is because Nitrogen is the "scarce" nutrient </span>
Answer: B. They allow for specific substance to travel throughout the cell.
Explanation: I know this because carrier proteins and channel proteins are some types of embedded proteins.
From what i have read up on in the past, They can but they don't really think with a "voice" in their head if that makes sense.
