Question

All living things need energy to perform their life processes. How and where do they get the energy that they need?
A.
the oxidation of food through the process of cellular respiration
B.
the production of carbon dioxide through the process of photosynthesis
C.
the absorption of light that radiates from the Moon
D.
the fixation of nitrogen gas from the atmosphere

Answer 1

A.

Living organisms obtain usable energy by oxidizing food molecules (like glucose) in cellular respiration, which produces ATP to power life processes. The other choices are incorrect: photosynthesis consumes CO2 and produces sugars (not CO2); moonlight is too weak to power most life; nitrogen fixation supplies nitrogen for building molecules, not the primary energy source.