A variegated leaf is tested for starch. Only the green parts turn blue-black. This shows that

  1. light is needed
  2. carbon dioxide is needed
  3. chlorophyll is needed for photosynthesis
  4. water is needed
Answer

C) chlorophyll is needed for photosynthesis

White parts lack chlorophyll and made no starch. O Level Biology · Topic 6 Plant Nutrition · 6.1 Photosynthesis

Biology MCQ · More O Level Biology: Plant Nutrition MCQs · Practise