Consider this living plant a system. To be alive, the plant needs energy. As a plant, it produces its own usable chemical energy by photosynthesis and uses that same energy through cellular respiration. One output of photosynthesis is a critical reactant or input for respiration. That is
Responses
A water.water.
B oxygen.oxygen.
C sunlight.sunlight.
D carbon dioxide.
D carbon dioxide.
The correct answer is D: carbon dioxide.
The correct answer is D) carbon dioxide.
To understand why carbon dioxide is the critical reactant or input for respiration, let's break down the processes of photosynthesis and cellular respiration in a plant:
Photosynthesis: In the presence of sunlight, plants use chlorophyll (pigment) in their leaves to convert carbon dioxide and water into glucose (a type of sugar) and oxygen. This process is carried out in special structures called chloroplasts.
6CO2 + 6H2O + sunlight → C6H12O6 (glucose) + 6O2
Cellular Respiration: Plants, like other living organisms, require energy for their metabolic processes. They obtain this energy by breaking down glucose through a process called cellular respiration. Oxygen is required for this process.
C6H12O6 (glucose) + 6O2 → 6CO2 + 6H2O + energy (ATP)
As you can see, the output of photosynthesis (oxygen) becomes an input for cellular respiration, while the input for photosynthesis (carbon dioxide) becomes an output for cellular respiration.
Therefore, carbon dioxide is a critical reactant or input for respiration - without it, plants would not be able to carry out cellular respiration and produce the necessary energy for their survival.