LI :To investigate the presence of starch in leaves Testing leaves for Starch LI :To investigate the presence of starch in leaves

What is photosynthesis?

Photosynthesis is the process by which green plants produce their own food

Photosynthesis Equation Light energy Carbon Dioxide Water GLUCOSE Oxygen

Plants make their own food - Glucose Glucose is a simple sugar made during photosynthesis in green plants Glucose can be stored or used by the plant as an energy source

Glucose Used up by the plant to grow Stored as Starch

We can test leaves for the presence of starch using iodine solution… Starch absent Starch present

Stage 1 Boil water in the beaker using the bunsen and collect leaf disc to put into boiling water Leave to boil for 5 minutes While you are waiting…… Fill in worksheet

Stage 2 Turn off the Bunsen – IMPORTANT Bring your boiling tube to the front and collect ethanol Remove leaf from water and put it in the ethanol. Put the boiling tube back into the beaker of hot water and leave for 5 minutes While you are waiting…. continue to fill in the worksheet

Stage 3 Remove leaf disc from the ethanol Rinse the leaf disc in the beaker of hot water Place the leaf disc on the dimple tray Test for starch using iodine solution Record results on the worksheet

Discussion of the results What colour did the leaf go? What did this tell us? Has photosynthesis occurred in the leaf?

Teacher demo

No starch present Plant kept in the dark Plants need sunlight for photosynthesis to occur

Plant starved of carbon dioxide No starch present Plants need carbon dioxide for photosynthesis to occur

Variegated leaf Plants need chlorophyll for photosynthesis to occur

What have we learned today? Success Criteria: I can state that green plants make their own food which may be stored as starch. I can successfully carry out an experiment to test leaves for starch I can name the limiting factors in the process of photosynthesis.