Biology · KS3 Y8 · Cells & Organisation

Testing a leaf for starch

Testing a leaf for starchFree5:49Heddy Score 3 of 7, below the standard

What you need to know

  • Boil the leaf in water for about 20 seconds to kill it, stopping its reactions and softening it.
  • Turn off the flame, then warm the leaf in ethanol in a hot-water bath to remove the chlorophyll, because ethanol is highly flammable.
  • Rinse the brittle leaf in warm water to soften it, then spread it on a white tile.
  • Add iodine solution: areas with starch turn blue-black, while areas without starch stay orange-brown.
  • In a variegated leaf only the parts that were green turn blue-black, which is evidence that chlorophyll is needed for photosynthesis.

In this clip

Runs 5:49, from 0:13 to 6:02 of the full video.

Heddy Score3/7, Below the standard
See the seven stars
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · passed. One idea, short enough to watch in one go.
  • Accessible · passed. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
On YouTube

344K views · 3.52K likes · Tom Dare 7.06K subscribers

As reported by YouTube on 2026-11-02. Not part of the Heddy Score.
How the Heddy Score works

Why we picked it

A real practical demonstration of every step of the starch test, with clear safety reasons and a striking variegated-leaf result.

Tom Dare on YouTubechecked 2026-10-22

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