An isotonic solution is a solution in which the amount of dissolved material is equal both inside and outside of the cell. Water still flows in both directions, but an equal amount enters and leaves the cell. Hope this helps. :)
Answer:
"U"-shaped, with peaks at the low and high extremes of beak size; disruptive selection
Unfortunately this question is incomplete as no options are provided. IN actual fact,<span> four muscles are involved in mastication. Three of these are responsible for biting down, namely the masseter, the temporalis and the medial pterygoid, whereas one, the lateral pterygoid, is responsible for opening of the jaw</span><span>. All four muscles help to move the jaw laterally.</span>
They are variables that cannot be changed or are purposefully not changed in an experiment.