Final answer:
The gas needed for the photosynthesis reaction is Carbon dioxide (B). Photosynthesis converts carbon dioxide and water into sugars and oxygen using sunlight, and it takes place in chloroplasts with chlorophyll.
Step-by-step explanation:
Photosynthesis and Its Requirements
The gas needed for the photosynthesis reaction is Carbon dioxide (B). Photosynthesis is a process where plants, algae, and some bacteria convert carbon dioxide and water into sugars/carbohydrates and oxygen using sunlight as an energy source. This process occurs in chloroplasts within plant cells, where a green pigment called chlorophyll captures light energy. The general equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, which shows carbon dioxide and water as reactants and sugars/carbohydrates and oxygen as products.
Thus, without carbon dioxide, the photosynthesis process would be hindered, ultimately affecting the production of essential compounds for plant growth and the release of oxygen, which is crucial for animal and human respiration.