Question

Construct an explanation to describe the cycling of matter and energy that occurs during photosynthesis. Use the chemical equation to provide evidence.

Answer 1

Photosynthesis reaction using chemical equation

light energy + 6CO₂ + 6H₂0 → C₆H₁₂0₆ + 6O₂

Explanation:  

• Photosynthesis is the process by which plants use sunlight to convert water and carbon dioxide into glucose and oxygen.

• Plants absorb carbon dioxide from the atmosphere via stomata, which are small openings in their leaves.

• Plants obtain water from the soil surrounding their roots, and water travels to the leaves via the xylem.

• The carbon dioxide and water molecules move into the cells of the mesophyll, the layer of ground tissue between the upper and lower epidermis, once inside the leaf. Photosynthesis is carried out within these cells by organelles known as chloroplasts, which use carbon dioxide and water.

• Their thylakoid membranes contain chlorophyll, a pigment that absorbs photons (light energy) from the sun and initiates the light-dependent reactions that occur within the thylakoids.

• Water molecules (H₂O) are broken down during these reactions. During light-dependent reactions, NADPH and ATP—high-energy molecules that power the production of glucose—are also produced. NADPH is formed by combining electrons and hydrogen ions from water. Hydrogen ions are also responsible for the conversion of ADP to ATP.

• The light-independent reactions of photosynthesis, also known as the Calvin cycle, break down carbon dioxide molecules (CO₂) into a form that may be used to generate glucose using enzymes in the stroma and energy-carrying molecules (ATP and NADPH) from the light-dependent reactions.
• In plants, mitochondria use cellular respiration to break down glucose to produce ATP. After a light-dependent reaction, glucose is converted into sugars like sucrose or carbohydrates like starch or cellulose.

• Phloem leaves the leaf and carries sugars to the root, storing them there for later use, or to other parts of the plant, where they provide energy for the plant's activities.