Photosynthesis is… …the process through which plants convert light energy to chemical energy in order to produce food The energy involved in photosynthesis.

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.

Question

Which of the following are necessary in order for photosynthesis to occur?

A. water

B. light energy

C. carbon dioxide

D. all of the above

Water, carbon dioxide, and lightEnergy are all needed in order forphotosynthesis to occur.

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.

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

A. undergoing photosynthesis.

B. undergoing the Calvin cycle.

C. undergoing cellular respiration.

D. 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.

Leaves contain chloroplasts.

Chloroplasts are:– capsule-shaped organelles– contained by two membranes– located inside the mesophyll cells of leaves

Question

Where in a plant would you expect to find the greatest number of chloroplasts?

A. root cells

B. stomata cells

C. leaf vein cells

D. mesophyll cells

Within a leaf, the chloroplasts are concentrated in the inner layer of tissue,which is known as the mesophyll.

Question

How do the mesophyll cells exchange gases with the outside environment?

A. through simple diffusionB. through active transportC. through endocytosis and exocytosisD. through openings in the leaf called “stomata”

Stomata allow carbon dioxide to betaken in and oxygen and water vapor to exit. For this reason, most plants keep their stomata closed for most of the day, when evaporation ismore likely.

Chloroplast Parts

Thylakoids: disk-shaped vesicles stacked inside the chloroplast

Granum: a stack of thylakoidsStroma: liquid material inside the

chloroplastChlorophyll: pigment located inside the

thylakoid that absorbs light energy; gives plants their green color

ChlorophyllChlorophyll

Question

Complete the following analogy.

mitochondrion : matrix :: chloroplast : _______

A. stroma

B. granum

C. thylakoid

D. inner membrane

Both the matrix and the stroma are metabolically-active, fluid-filled areasinside the innermost membranes of theorganelle of which they are a part.

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.”

Four Processes of the Light-Dependent Reactions

1. Light Absorption

2. Electron Transport

3. Oxygen Production

4. ATP Formation

Question

What is the first step in the light-dependent reactions?

A. formation of ATP

B. absorption of light

C. production of oxygen

D. transport of electrons

Light initiates the process of photosynthesis by energizing the electrons in the reaction-centers of photosystems I & II.

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.”

Question

Why is it misleading to call the Calvin cycle reactions the “dark reactions?”

A. They cannot happen in the dark.

B. They can only happen in the light.

C. They can only happen in the dark.

D. 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.

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.

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.