How does the structure of the alveoli allow for its function of gas exchange? Alveolar sacs have space to hold mucus that makes gas exchange easier.
Alveolar sacs rely on valves to ensure that air flows only in one direction.
Alveolar sacs are located within muscles that contract, which increases gas exchange.
Alveolar sacs are surrounded by thin capillaries where gases can be exchanged.

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.

Always use significant figure rules. remember that these rules apply to all numbers that are measurements. a car travels 6 miles north, 3 miles east, and then 2 miles south. what is the distance traveled? a.7 b.11

The diagram shows the layers of earth. convection currents in which region influence the movement of tectonic plates