Chapter 6

6.1  Overview of Photosynthesis

Photosynthesis transforms solar energy into the chemical energy of carbohydrates (sugars).


Photosynthetic organisms include plants, algae, and cyanobacteria


The products of photosynthesis provide both food and fuel (coal, oil, wood) to humans.


Plants and Photosynthesis

The green portions of plants, such as leaves and pine needles, carry out photosynthesis, using carbon dioxide and water as reactants.

Carbon dioxide enters leaves through openings called stomata.

The carbon dioxide and water diffuse into the chloroplast, the site of photosynthesis. 


Photosynthesis in leaves


The equation for photosynthesis can also be written in another form to show the formation of the product, glucose.

In the equation below, CH2O is the general formula for a sugar like glucose.


Photosynthesis chemical equation

Toggle open/close quiz question

Which statement best describes the function of stomata?
    a.the light reactions occur here
    b.they allow gases into and out of the leaves
    c.the Calvin Cycle occurs here
    d.It holds the chlorophyll



Photosynthesis has two sets of reactions

1. The light dependent reactions (or light reactions)

Use light and water to make ATP and NADPH

 2. The Calvin Cycle (light independent reactions or dark reactions)

The ATP and NADPH from the light reactions are used to convert carbon dioxide into sugar.


 Toggle open/close quiz question

The light dpendent reactions make sugar.



Extra Help


More on photosynthesis