A direct observation usually refers to observing a behavior and knowing exactly what is happening. For example, if I see a pigeon peck at some bread, I have observed it pecking. With direct observation, I cannot assume it is eating, that it is hungry, that it has any intention whatsoever. All I know is that it pecks.
<span>Cannot carry normal levels of oxygen to cells :)</span>
Answer: Membrane transport proteins are specific and selective for the molecules they move, and they often use energy to catalyze passage. Also, these proteins transport some nutrients against the concentration gradient, which requires additional energy.
Explanation:
