Explanation: Rivalry
There is safety in numbers, and with that, they can run together more often without the fear of being attacked, and must push themselves to match others, therefor getting fit
Answer:
i believe the answer is 3
not positive though
Explanation:
The answer is: "sexual dimorphism" .
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Answer:
cellular membranes
Explanation:
Cellular membranes are selectively permeable because they allow only certain molecules to cross into and out of the cell. The phospholipid bilayer is a selectively permeable membrane that surrounds all biological cells. The movement of molecules across the cell membrane bilayer can occur by passive transport (does not require energy) or active transport (requires energy). For example, water molecules pass passively through the cell membrane (passive transport), while other molecules pass through transmembrane proteins against a concentration gradient (active transport).
