Cold packs are designed to become very cold when activated. when the pack is activated, a chemical reaction occurs to make the temperature of the cold pack decrease. what must be true of this chemical reaction? a. the reaction releases energy to its surroundings. b. the products and reactants have the same amount of energy. c. the products have less energy than the reactants. d. the reaction absorbs energy from its surroundings.

Alichen is an organism that structurally appears to be a single organism. but a lichen is actually two different organisms—a fungus and green algae—living together as one organism. the fungal partner derives its nutrition from the photosynthesizing algae. how does a lichen differ in its photosynthetic activity from elysia chlorotica, the sea slug that’s considered to be a photosynthesizing animal? a. in lichens, the fungi photosynthesize on their own, while elysia chlorotica forms a relationship with a photosynthesizing plant. b. in lichens, the relationship with the algae lasts throughout the life cycle, but in elysia chlorotica, the relationship occurs only during the immature juvenile stage of the slug’s life cycle. c. lichens can photosynthesize only because of the living algal partner, while elysia chlorotica incorporates chloroplasts from algae into its cells. d. in lichens, the association between the fungi and algae is permanent, while elysia chlorotica associates with a photosynthesizing organism only when it requires food.

When the oxygen produced by photosynthetic plants in the water dissolves in the water, which of these is being formed?

In which part of the body is a ball-and-socket joint found?