PHOTOSYNTHESIS STUDY GUIDE
For AQA A-Level Biology
The light dependant reaction
The light dependant reaction occurs in the thylakoid membrane and
happens via a series of steps. These occur as follows:
1. Light is absorbed by the chlorophyll and this energy is transferred to a
pair of electrons. These electrons become excited. This process is
called photoionisation.
2. Electrons are then propelled out of the chlorophyll.
3. This movement of electrons through the electron transport chain
releases energy. This energy allows protons to be actively
transported from the stroma to the thylakoid space.
4. Electrons at the end of the electron transport chain react with NADP
and a proton to produce NADPH (also known as reduced NADP).
5. Protons move back into the stroma through the enzyme ATP
synthase via the process of chemiosmosis. This process occurs as
the protons are moving down their concentration gradient.
This diagram depicts the process of the light dependent reaction:
For AQA A-Level Biology
The light dependant reaction
The light dependant reaction occurs in the thylakoid membrane and
happens via a series of steps. These occur as follows:
1. Light is absorbed by the chlorophyll and this energy is transferred to a
pair of electrons. These electrons become excited. This process is
called photoionisation.
2. Electrons are then propelled out of the chlorophyll.
3. This movement of electrons through the electron transport chain
releases energy. This energy allows protons to be actively
transported from the stroma to the thylakoid space.
4. Electrons at the end of the electron transport chain react with NADP
and a proton to produce NADPH (also known as reduced NADP).
5. Protons move back into the stroma through the enzyme ATP
synthase via the process of chemiosmosis. This process occurs as
the protons are moving down their concentration gradient.
This diagram depicts the process of the light dependent reaction:
