Teach This To Me

Photosynthesis — What You Need to Know

The One-Sentence Version: Plants use sunlight, water, and carbon dioxide to make glucose (food) and release oxygen.

The Formula: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

Where It Happens: Inside chloroplasts — specifically in structures called thylakoids (light reactions) and the stroma (Calvin cycle). Chlorophyll is the green pigment that captures light energy.

Two Main Stages:

1. Light-dependent reactions: Happen in thylakoid membranes. Sunlight splits water molecules, producing ATP and NADPH (energy carriers) and releasing oxygen as a byproduct.

2. Calvin Cycle (light-independent): Uses ATP and NADPH to convert CO₂ into glucose. Doesn't need light directly but depends on products from stage 1.

Common Misconception: Plants don't “breathe in” CO₂ the way animals breathe. Gas exchange happens through tiny pores called stomata on the undersides of leaves.

Why Students Care: Without photosynthesis, there's no oxygen and no food chain. It's the foundation of nearly all life on Earth.