Bacteria add carbon to the carbon cycle by being consumed by larger organisms, such as plankton.

decomposing dead organisms.

exchanging carbon dioxide and oxygen gases.

performing photosynthesis.

1) (b)

2) (d)

3) (c)

4) (a)

5) (d)

Explanation:

1) (b) carbon sink

2) (d) performing photosynthesis.

3) (c) organisms exhale carbon dioxide.

4) (a) cacti

5) (d) mitochondria

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.