I believe it is option A. that is what I would go with.
It's the first option for both questions i think
Answer:
Gas
carbon
dioxide
Relative Abundance
trace gas
Description
required for photosynthesis
Gas
nitrogen
Relative Abundance
most abundant gas in the atmosphere
Description
incorporated as a major component of proteins and DNA
Gas
oxygen
Relative Abundance
second most abundant gas in the atmosphere
Description
required for aerobic cellular respiration
Explanation:
Carbon dioxide (CO2) gas is only 0.04% by volume of the atmosphere. So, it is found in trace. It is used by plants and some cyanobacteria and algae in photosynthesis for preparing food in the presence of light/
Nitrogen (N2) gas is about 78% by volume of the atmosphere, and hence it is the most abundant gas in the atmosphere. It is a major component of proteins (as amino acids) and DNA (as nucleic acids).
Oxygen gas (O2) is about 28% by volume of the atmosphere; hence it is second most abundant gas after nitrogen gas.
Aerobic cellular respiration is a process in which food particles are broken down by oxygen for the release of energy in the form of ATP (adenosine triphosphate)
