Answer:
Famine.
Explanation:
Famine, a shortage of water or food, will often result in a significant population decrease.
Answer:
False
Explanation:
Sensory neurons send messages to the central nervous system.
Answer:
Active transport: movement against a gradient To move substances against a concentration or electrochemical gradient, a cell must use energy. Active transport mechanisms do just this, expending energy (often in the form of ATP) to maintain the proper concentrations of ions and molecules in living cells.
Cells is a basic unit of life
3,000,000,00 is prolly estimated