Biologist ___________________________
Date ______________
8-2 PowerPoint Notes – Photosynthesis Overview
Light
____________ from the sun travels to Earth in the form of light.
Sunlight is a mixture of different wavelengths, many of which are ____________ to our eyes
and make up the visible spectrum.
Pigments
Plants gather the sun’s energy with light-___________ molecules called pigments.
The plants’ principal pigment is ___________.
Chloroplasts
Chloroplasts contain saclike photosynthetic membranes called ___________, which are
interconnected and arranged in stacks known as ___________.
The fluid portion outside of the thylakoids is known as the ___________.
Energy Collection
When chlorophyll absorbs light, a large fraction of the light energy is transferred to
electrons. These high-energy ___________ make photosynthesis work.
High-Energy Electrons
The high-energy electrons produced by ___________ are highly reactive and require a special
“carrier.”
Think of a high-energy electron as being similar to a hot potato. If you wanted to move the
potato from one place to another, you would use an oven mitt —a carrier—to transport it.
Plants use electron carriers to transport high-energy ___________ from chlorophyll to other
molecules.
NADP+ (nicotinamide adenine dinucleotide phosphate) is a ___________ molecule.
NADP+ accepts and holds two high-energy ___________, along with a ___________ ion (H+). In
this way, it is converted into ___________.
The NADPH can then carry the high-energy electrons to chemical reactions elsewhere in
the cell.
An Overview of Photosynthesis
Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into highenergy sugars and oxygen.
In symbols:
6 ____ + 6 _____  ____________ + 6 _____
In words:
____________ + ____________  ____________ + ____________
Plants use the sugars generated by photosynthesis to produce complex carbohydrates
such as starches, and to provide ____________ for the synthesis of other ____________,
including proteins and lipids.
Light-Dependent Reactions
Photosynthesis involves two sets of reactions.
The first set of reactions is known as the light-dependent reactions because they require
the direct involvement of ____________ and light-absorbing pigments.
The light-dependent reactions use energy from sunlight to produce _______and _________.
These reactions take place within the ____________ membranes of the chloroplast.
_____ is required as a source of electrons and hydrogen ions. _____ is released as a
byproduct.
Light-Independent Reactions
During light-independent reactions, ATP and NADPH molecules produced in the lightdependent reactions are used to produce high-energy ________ from ____________.
_____ light is required to power the light-independent reactions.
The light-independent reactions take place outside the thylakoids, in the ____________.
Questions
1. In the process of photosynthesis, plants convert the energy of sunlight into chemical energy
stored in the bonds of _________.
2. Photosynthetic organisms capture energy from sunlight with ________.
3. The plant’s principal pigment is _______.
4. Photosynthesis takes place in ___________.
5. T or F - Chloroplasts contain an abundance of saclike photosynthetic membranes called
thylakoids.
6. T or F - The fluid portion of the chloroplast, outside of the thylakoids, is known as the
matirx.
7. Raising the energy levels of electrons on the chlorophyll molecule, light energy can produce a
steady supply of _______________electrons, which is what makes photosynthesis work.
8. An electron _________is a compound that can accept a pair of high-energy electrons and
transfer them, along with most of their energy, to another molecule.
9. NADP+ is converted to ______________as it accepts and transfers electrons to chemical
reactions elsewhere in the cell.
10. What is the overall equation of photosynthesis?
11. The light- ______________reactions produce ATP and NADPH from sunlight in the
thylakoid membranes.
12. The light-______________t reaction in the stroma, sugars are created from carbon dioxide
using the ATP and NAPH from the light-dependent reactions.