Question

The carbon that plants need for photosynthesis comes from
A.
carbon molecules dissolved in water.
B.
carbon molecules that the plant produces.
C.
carbon atoms from the breakdown of food.
D.
carbon dioxide gas in the atmosphere.

Answer 1

D. Carbon dioxide gas in the atmosphere.

Plants take in CO2 through stomata (or dissolved CO2/bicarbonate in water) and use the carbon atoms from CO2 to build sugars during photosynthesis.