also known as blue-green bacteria, or blue-green algae) can also photosynthesize. Algae and
cyanobacteria are important in aquatic environments as sources of food for larger organisms.
Photosynthesis mostly takes place in the leaves of a plant. The green pigment in leaves,
chlorophyll,helps to capture solar energy. And special structures within the leaves provide
water and carbon dioxide, which are the raw materials for photosynthesis. The veins within
a leaf carry water which originates from the roots, and carbon dioxide enters the leaf from
the air through special pores calledstomata(Figure4.7).
Figure 4.7: Stomata are special pores that allow gasses to enter and exit the leaf. ( 4 )The water and carbon dioxide are transported within the leaf to thechloroplast(Figure
4.8), the organelle in which photosynthesis takes place. The chloroplast has two distinct
membrane systems; an outer membrane surrounds the chloroplast and an inner membrane
system forms flattened sacs calledthylakoids. As a result, there are two separate spaces
within the chloroplast. The interior space that surrounds the thylakoids is filled with a fluid
calledstroma.The inner compartments formed by the thylakoid membranes are called the
thylakoid space.
The overall chemical reaction for photosynthesis is 6 molecules of carbon dioxide (CO 2 )
and 6 molecules of water (H 2 0), with the addition of solar energy, yields 1 molecule of
glucose (C 6 H 12 O 6 ) and 6 molecules of oxygen (O 2 ). Using chemical symbols the equation is
represented as follows:
6CO 2 + 6H 2 O!C 6 H 12 O 6 + 6O 2