Photosynthesis: quick revision, 12 bites

Photosynthesis: Turning Light Into Food

Sunlight becomes your food. Literally.

Photosynthesis is the process where green plants use **light energy** to convert **carbon dioxide** and **water** into **glucose** and **oxygen**.

Takeaway. Photosynthesis stores solar energy as chemical energy in glucose — the base of almost every food chain.

Key Terms You Must Know

Four words unlock the whole chapter.

Takeaway. Chlorophyll traps light; chloroplasts host the reaction; stomata let gases in and out.

How Photosynthesis Happens: Step by Step

From sunlight to sugar in four moves.

The overall reaction needs **light**, **chlorophyll**, **CO₂**, and **water** — remove any one and photosynthesis stops.

Takeaway. Light splits water, CO₂ is fixed into glucose, and oxygen is released.

Where Photosynthesis Happens

The leaf is a solar-powered factory.

Takeaway. Leaves are built for photosynthesis: chloroplasts capture light, stomata handle gases, veins supply water.

Why Photosynthesis Keeps You Alive

Every breath you take starts here.

Takeaway. No photosynthesis = no oxygen, no food, no life as we know it.

Plants Don't 'Eat' Soil — They Make Food

Soil isn't food. It's raw material.

Takeaway. Soil provides water and minerals; food is made in the leaves using sunlight.

Photosynthesis vs Respiration

Opposite reactions, same planet.

Takeaway. Photosynthesis stores energy; respiration releases it — they are complementary, not the same.

Exam Tip: Nail the Equation

One equation, many marks.

Takeaway. Write the equation with light and chlorophyll above the arrow to score full marks.

Remember the Inputs: 'CLW'

Three letters, one reaction.

Takeaway. CLW — Carbon dioxide, Light, Water — are the three inputs plants need.

Oxygen Is Just a By-Product

Plants don't make oxygen for us.

Oxygen is released as a **waste product** of photosynthesis — plants don't make it on purpose. The oxygen comes from **splitting water molecules**, not from carbon dioxide.

Takeaway. The oxygen we breathe is a leftover from water being split during photosynthesis.

Real Application: Why Farmers Use Greenhouses

Control the inputs, boost the output.

Takeaway. Greenhouses work because they optimise the conditions photosynthesis needs.

Don't Confuse Chlorophyll and Chloroplast

One is the pigment, one is the room.

Takeaway. Chloroplast = the site; chlorophyll = the pigment inside it.