Answer:
Since the cell membrane is semi-permeable, the likelihood of substance L entering the cell attached to a large protein is lower than that of substance L free in the culture. Substance L enters the cell membrane through active transport, but the cell membrane may block the larger protein, thus blocking substance L, if it is attached to the large protein.
Explanation:
A positive control is when you test your experiment against something where you know what the effects will be, whereas a negative control would be when you test the experiment with something you know will have no effect.
Answer: B. Semicircular canals
Explanation: Receptors of equilibrium are located in the middle part of the oval-shaped bone labyrinth located in the inner ear. This membrane labyrinth has three bony channels that contain perilymph in it. In them again lie the semicircular membrane channels and contain endolymph and containing receptors for equilibrium. Thus the purpose of the ear is not only good hearing but also a sense of balance.