chapter 42 - circulation and gas exchange

Question 1

small molecules can move between cells andtheir surroundings by (spell)

Answer 1

diffusion; only efficient over small distances

Question 2

in most animals, cells exchange materials with the environment via a _______ _____ ______ ______

Answer 2

fluid-filled circulatory system

Question 3

gastrovascular cavities

Answer 3

• function in the digestion and distribution of substances throughout the body
• helpful in animals that don’t have a circulatory system (cnidarians, flatworms)