<span> MitochondriaMitochondria are rod-shaped organelles that can be considered the power generators of the cell, converting oxygen and nutrients into adenosine triphosphate (ATP). ATP is the chemical energy "currency" of the cell that powers the cell's metabolic activities. This process is called aerobic respiration and is the reason animals breathe oxygen. Without mitochondria (singular, mitochondrion), higher animals would likely not exist because their cells would only be able to obtain energy from anaerobic respiration (in the absence of oxygen), a process much less efficient than aerobic respiration. In fact, mitochondria enable cells to produce 15 times more ATP than they could otherwise, and complex animals, like humans, need large amounts of energy in order to survive.</span>
The best possible scenario for the giraffes with longer necks to survive would be one in which all the lower leaves somehow disappear! This would mean only giraffes with longer necks can eat therefore those will have a better chance of surviving. Luckily the answer that fits that perfectly would be...
D. Monkeys swarm in and tear off all of the lower leaves to use for shelters.
Answer:1 : substratum. 2 : the base on which an organism lives the soil is the substrate of most seed plants. 3 : a substance acted upon (as by an enzyme)