Question

Photosynthesis is the process by which a plant makes food. What does this process produce?
A. Glucose and oxygen
B. Water, carbon dioxide and sugar
C. Carbon dioxide and sugar
D. Oxygen and proteins

Answer 1

Plants convert solar energy into chemical energy through a concerted process of photosynthesis, which is then released to power the organism's metabolic processes through cellular respiration. Photosynthesis is a process in which producers use the sun's energy to create food, i.e. chemical energy, which is subsequently transmitted to consumers in every ecosystem. Organisms who can perform photosynthesis are called photoautotrophs.

Complete solution:
Option (A): In the process of photosynthesis performed by plants, water molecules are at first split into molecular oxygen and ATP, NADH are produced, in a light dependent reaction. This ATP and NADH are then utilized to produce glucose in a light independent reaction, also called dark reaction. Thus, ultimately in photosynthesis performed by plants glucose and oxygen are produced.
Thus, Option (A) is correct.

Additional information:
Option (B): Water is the electron donor in oxygenic photosynthesis performed by plants while carbon dioxide acts as a carbon source in the production of sugars. Thus, Water and Carbon dioxide are reactants in photosynthesis and not products.
Thus, Option (B) is incorrect.
Option (C): Carbon dioxide is the carbon source in photosynthetic dark reactions which is used to produce sugars.
Thus, Option (C) is incorrect.
Option (D) Proteins are not produced in the process of photosynthesis.
Thus, Option (D) is also incorrect.

Note:
In oxygenic photosynthesis oxygen is evolved after splitting of water molecules which serves as an electron donor. Carbon fixation is the process of converting carbon dioxide into sugars. Because carbon fixation is a redox reaction, photosynthesis must provide both a source of energy and the electrons required for the reduction reaction of carbon dioxide into a carbohydrate.