Final answer:
Carbon dioxide and water, byproducts of cellular respiration, are used by chloroplasts in plants to synthesize carbohydrates through photosynthesis, demonstrating the cyclical nature of matter and energy in biological systems.
Step-by-step explanation:
The byproducts from cellular respiration, carbon dioxide and water, are the very molecules that the chloroplasts require to build carbohydrates during photosynthesis. This is part of a broader biological cycle where, during photosynthesis, plants convert carbon dioxide and water into carbohydrates, such as glucose, using sunlight as the energy source.
The equation for photosynthesis is 6CO2 + 6H2O + energy → C6H12O6 + 6O2. Conversely, during cellular respiration, organisms break down carbohydrates to produce energy, carbon dioxide, and water. This cycle is a prime example of the conservation of matter and energy in biological systems, with neither truly going to waste but rather being continuously recycled.