(A) Water vapor is evaporated at body temperature.
(B) Water forms the basis of sweat when it comes in contact with nerve endings.
(C) Sweat percolates through capillaries into the tissues, where it cools in a series of cooler and cooler spaces in which water molecules are removed from solution by evaporation or condensation reactions. The process continues until all the free water has been removed, leaving what is called an ice crystal, which conducts heat away more slowly than liquid water would do because of its high density (specific heat). Other minerals or ions may be added to make up for the missing components; thus salt-free sweat contains little sodium chloride but substantial potassium chloride and calcium sulfate. When most of these salts have dissolved, there remains only about 0 percent moisture—a fairly dry “dew” that then evaporates completely to leave nothing behind except some large amounts of solids left over from crystallization that can irritate skin if not washed off quickly enough.
Possible Answers: B
21—Correct Answer: D This question requires us to know something about how plants use light energy for photosynthesis . Photosynthesis occurs when light strikes chlorophyll molecules on plant cells so they absorb visible wavelengths while reflecting invisible ones out again as infrared radiation , producing usable chemical energy for growth and development . A leaf absorbs visible blue light , converting some green wavelengths into red pigments used mainly for making