B1.4.2 Flashcards
What is the test for starch in a leaf
Take leaf place it in boiling water to kill it then place it into boiling ethanol to remove all chlorophyll. Wash leaf to remove ethanol spread it out on a white tile. Add a few drops of iodine solution onto leaf is starch is present it will go from yellow brown to blue black.
If a plant can’t photosynthesise what can’t be produced
Starch can’t be produced
How can you de-starch plants
Done by keeping plants in dark for 24 hours
How to prove chlorophyll is needed
Variegated leaves only have chlorophyll in certain areas. This means that after de-starched you can test for starch and only the green plants will turn blue-black
How to prove carbon dioxide is needed
Take plant and place it in a polythene bag. Add a pot of soda lime which absorbs CO2 and water vapour. Place in sunlight for several hours. Then test for presence of starch. should be yellow-orange.
How to prove oxygen is given off
Place upturned test tube over aquatic plant. Put the apparatus for max photosynthesis. When collected tube of gas hold a glowing splint inside the tube and it’ll relight as oxygen is present.
How to prove light is needed
Take de starched plant and cover part of one of its leaves with black card or tin foil. Light can’t reach the covered area. Place it in sunlight then test for the presence of starch and the covered part should turn yellow-black.
