Biology · Photosynthesis · Need for chlorophyll

The variegated leaf test for chlorophyll

A variegated leaf has green chlorophyll-containing regions and pale regions without chlorophyll. After the standard starch test, only the green regions go blue-black — showing chlorophyll is needed for photosynthesis.

Step 1

Leave in bright light for 6 h

Step 2

Boil leaf in water for 1 minute

Step 3

Boil in ethanol (water bath) 3 min

Step 4

Rinse leaf in warm water

Step 5

Add iodine solution

Exam-style questions

1. Why boil the leaf in water first?

2. Why boil in ethanol?

3. After iodine: GREEN regions go blue-black; WHITE stay orange. What does this show?

4. Why rinse in warm water after ethanol?