How can marine animals such as sharks live in a salt water?
A) They increase or decrease the amount of urea in their blood until the blood is isotonic with the environment.
B) They increase the amount of urea in their blood until the blood is hypertonic with the environment.
C) They decrease the amount of urea in their blood until the blood is hypotonic with the environment.
D) They contain impermeable membranes which do not allow the salt water to cross into their cells.
E) They contain blood that has the same salt concentration as is present in salt water.

Question

Quizplus · Accepted Answer

Sharks increase or decrease the urea in their blood until it is isotonic with the salt water. Their cell membranes are permeable to the water and only by making their blood isotonic can they prevent their cells from shrinking.

How Can Marine Animals Such as Sharks Live in a Salt