Experiment 11 — Does a Leaf Need Light to Make Food?

Topic: Biology · Classes 6–7 · Nutrition in plants: photosynthesis and the starch test

Aim: Prove that light is needed for a leaf to make starch — with a proper control.

Daily: Every grain of rice and every chapati began as sunlight captured by a leaf. Plants are the only organisms that make food from light, which is why every food chain on Earth starts with them.

Question: Why must the plant be kept in the dark for two days before this experiment?

Exp: Destarching means any starch found afterwards was definitely made during the test.

Question: Photosynthesis needs light, water, chlorophyll and…

Exp: CO₂ from the air supplies the carbon in glucose.

Question: The gas released during photosynthesis is…

Exp: Which is why plants matter so much to every animal.

Question: Iodine turning blue-black on a leaf shows…

Exp: Starch is the stored food, so it shows food was made.

Question: The covered strip in this experiment acts as…

Exp: It is identical except for the one factor being tested.