Question

Use a diagram to model the relationship
between photosynthesis and cellular
respiration

Answer 1

Here is a clear diagram (ASCII) showing how photosynthesis and cellular respiration are linked, followed by brief notes.

Sunlight
↓
[Chloroplast]
(Photosynthesis)
Inputs: 6 CO2 + 6 H2O + light
Outputs: C6H12O6 + 6 O2
Equation: 6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
↓
Glucose + O2
↓
[Mitochondrion]
(Cellular respiration)
Inputs: C6H12O6 + 6 O2
Outputs: 6 CO2 + 6 H2O + ATP + heat
Equation: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ~30–32 ATP + heat
↓
CO2 + H2O (returned to air/water)
↺ (used again by chloroplasts)

Key points:
- Photosynthesis (in chloroplasts of plants, algae, some bacteria) captures light energy and stores it as chemical energy in glucose; it is endergonic (energy‑requiring).
- Cellular respiration (in mitochondria of eukaryotes and in many bacteria) breaks glucose down to release energy stored as ATP; it is exergonic (energy‑releasing).
- The products of photosynthesis (glucose and O2) are the reactants for respiration; the products of respiration (CO2 and H2O) are reactants for photosynthesis—forming a biological cycle of matter.
- Energy flow is one‑way: light → chemical energy (glucose) → ATP → cellular work + heat.