Answer:
The source of the elements that make up glucose in a plant is primarily carbon dioxide (CO2) from the air, water (H2O) from the soil through the roots, and energy from sunlight.
During photosynthesis, chlorophyll in the plant's leaves absorbs light energy and uses it to convert carbon dioxide and water into glucose and oxygen. This process involves a series of complex chemical reactions, collectively called the Calvin cycle, that occur within specialized structures in plant cells called chloroplasts.
In the first stage of the Calvin cycle, carbon dioxide molecules in the air are captured by an enzyme called rubisco and combined with a molecule called ribulose bisphosphate (RuBP). This results in the formation of an unstable molecule that quickly breaks down into two molecules of a three-carbon compound called 3-phosphoglycerate (3PG).
Next, the energy from sunlight is used to convert the 3PG molecules into a different three-carbon compound called glyceraldehyde 3-phosphate (G3P). Some of the G3P molecules are used to make glucose, while others are used to regenerate the original RuBP molecule that can be used in the next cycle.
Finally, the glucose molecules are transported throughout the plant and used as a source of energy for cellular respiration, which releases the stored energy in the glucose molecules to power various cellular processes in the plant. The oxygen produced during photosynthesis is released into the air as a byproduct of the process.
In summary, the source of the elements for the glucose that the plant makes is carbon dioxide from the air, water from the soil, and energy from sunlight.
Step-by-step explanation: