1. Photosynthesis in Detail

2. Photosynthesis is…
…the process through which plants convert light energy to chemical energy in order to produce food
The energy involved in photosynthesis is eventually stored in the chemical bonds of molecules like glucose.

3. Question water light energy carbon dioxide all of the above
Which of the following are necessary in order for photosynthesis to occur?
water
light energy
carbon dioxide
all of the above
Water, carbon dioxide, and light
Energy are all needed in order for
photosynthesis to occur.

4. Why are Plants Green?
Objects appear a certain color because they reflect that color.
Plants are filled with chlorophyll, a pigment that reflects green light.
Plants absorb mostly red and blue light and reflect green light.

6. Question
In the simulation on the previous slide, the oxygen meter displays a negative number when the light is off. This is because the plant is
undergoing photosynthesis.
undergoing the Calvin cycle.
undergoing cellular respiration.
undergoing combustion reactions.
Like all organisms that undergo aerobic cellular respiration, plants use oxygen to release the chemical energy stored in glucose and make ATP.

7. Leaves contain chloroplasts.
Chloroplasts are:
capsule-shaped organelles
contained by two membranes
located inside the mesophyll cells of leaves

8. Question
Where in a plant would you expect to find the greatest number of chloroplasts?
root cells
stomata cells
leaf vein cells
mesophyll cells
Within a leaf, the chloroplasts are
concentrated in the inner layer of tissue,
which is known as the mesophyll.

9. Question through simple diffusion through active transport
How do the mesophyll cells exchange gases with the outside environment?
through simple diffusion
through active transport
through endocytosis and exocytosis
through openings in the leaf called “stomata”
Stomata allow carbon dioxide to be
taken in and oxygen and water vapor
to exit. For this reason, most plants
keep their stomata closed for most
of the day, when evaporation is
more likely.

10. Chloroplast Parts
Thylakoids: disk-shaped vesicles stacked inside the chloroplast
Granum: a stack of thylakoids
Stroma: liquid material inside the chloroplast
Chlorophyll: pigment located inside the thylakoid that absorbs light energy; gives plants their green color

11. Chlorophyll

12. mitochondrion : matrix :: chloroplast : _______
Question
Complete the following analogy.
mitochondrion : matrix :: chloroplast : _______
stroma
granum
thylakoid
inner membrane
Both the matrix and the stroma are
metabolically-active, fluid-filled areas
inside the innermost membranes of the
organelle of which they are a part.

13. Light-Dependent Reactions
In this set of reactions, the energy in sunlight is captured and used to make energy-storing compounds. (ATP & NADPH)
These reactions take place inside the thylakoid membranes.
Also known as the “Light Reactions.”

14. Four Processes of the Light-Dependent Reactions
Light Absorption
Electron Transport
Oxygen Production
ATP Formation

17. Question What is the first step in the light-dependent reactions?
formation of ATP
absorption of light
production of oxygen
transport of electrons
Light initiates the process of
photosynthesis by energizing the electrons in the reaction-centers
of photosystems I & II.

18. The Light-Independent Reactions
Includes the Calvin cycle.
Light does not play a role in these reactions; they can take place in the light or the dark.
Sometimes misleadingly called the “dark reactions.”

19. Question
Why is it misleading to call the Calvin cycle reactions the “dark reactions?”
They cannot happen in the dark.
They can only happen in the light.
They can only happen in the dark.
They can happen any time—light or dark.
These reactions are not dependent on light energy. They can occur as long as CO2, ATP, and NADPH are present.

20. The Calvin Cycle
The light independent reactions form a cycle, or circular series of reactions.
This cycle is called the “Calvin Cycle” after the person who first described it, Melvin Calvin.

21. This is as detailed as we’ll get!
The Calvin Cycle uses CO2 along with ATP and NADPH from the light reactions to form the building blocks for glucose (G3P).