Answer:
C. carrier proteins
Explanation:
The core of the cell membrane is made up of hydrophobic tails of phospholipid. It does not allow the water-soluble material to move across the membrane. Carrier proteins are the membrane proteins that serve as transporters.
The carrier proteins bind the ion or water-soluble molecules and undergo changes in shape. This transports the molecule across the membrane. Carrier proteins serve in passive facilitated diffusion and active transport. The carrier proteins involved in facilitated diffusion transport the molecules down the concentration gradient without any expenditure of energy.
Overpopulation is the overcapacity of people in a community.
It has increasingly got hotter
