Class F have been studying leaves and photosynthesis. Photosynthesis is the chemical reaction that plants use to transform carbon dioxide and water into glucose and oxygen.

                       Sunlight energy

6CO₂  + 6H₂O ————> C₆H₁₂O₆  + 6O₂

Chlorophyll (the green pigment in plants) transforms the Sun’s energy into chemical energy which powers this chemical reaction. If the glucose produced by the plant is not used immediately, it is transformed into starch and stored in the leaves.

Class F tested leaves for photosynthesis using iodine which undergoes a colour change in the presence of starch. The black parts in the leaves show that starch is present, therefore the leaf has been photosynthesising in the past 24 hours.

Students also looked at the underside of leaves to see if we could identify the stomata (pores) of the leaf. This is where carbon dioxide enters the leaf and also where oxygen leaves the leaf. Using our microscope with the USB camera, we were able to take a photo of the stomata. We were able to clearly identify the stomata and the guard cells around them which control whether the stomata are open or closed. This is part of the ecosystem processes topic.