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converts solar energy into chemical energy


sustain themselves


uses the energy of sunlight to make organic molecules from H2O and CO2


where CO2 enters and O2 exits the leaf


the interior tissue of the leaf, chloroplasts are found here

How many chloroplasts are in a mesophyll cell



dense fluid in chloroplast

Photosynthesis Redox Process

H2O is oxized, CO2 is reduced

What two reactions are part of Photosynthesis

Light reactions and the Calvin Cycle

Light Reactions

split H2O, release O2, reduce NADP to NADPH, generate ATP from ADP by photophosphorylation

The Calvin Cycle (stroma) forms sugars from

CO2 usng ATP and NADPH

The carbon cycle begins with

Carbon fixation

Carbon fixation

changes CO2 into organic molecules

What are solar powered chemical factories


Chloroplasts transform light into chemical energy by using


Electromagnetic Radiation


Light travels in

Rhythmic Waves

What determines the type of electromagnetic energy?


What is the entire range of electromagnetic energy

Electromagnetic Spectrum

Visible Light

Wavelengths that produce the color we see


Light particles


substances that absorb visible light

Different pigments absorb different


Why do leaves appear green?

Chlorophyll reflects and transmits green

A spectrophotometer can be used to measure

the absorption spectrum of a substance

Absorption Spectrum

Graph plotting a pigments light absorption versus wavelengths


Relative effectiveness of different wavelengths of radiation in driving a process

When a pigment absorbs light

it goes from ground state to excited state

When excited electrons fall back to the ground state

photons are given off (fluorescence)


Reaction center complex surrounded by light-harvesting complexes

Light Harvesting Complex

pigment molecules bound to proteins

What funnels the energy of photons to the reaction center?

Light Harvesting Complex

Primary Electron Acceptor

Accepts an excited electron from Chlorophyll A

What is the first step in Light Reactions?

Electron transfer from Chlorophyll A to primary electron acceptor

Which Photosystem absorbs a wavelength at 689 nm

Photosystem II

PS II reaction center chloropyhll A is called


Which Photosystem absorbs a wavelength at 700 nm

Photosystem I

Two routes for electron flow during light reactions

Cyclic and Linear

Linear Electron Flow

Primary Pathway: involves both photosystems and produces ATP and NADPH using light energy

Cyclic Electron Flow

uses only Photosystem I and produces ATP (but NOT NADPH)


Generate ATP in Mitochondria and Chloroplast

Chemiosmosis in the Mitochondria, chemical energy is transferred from what to what?

Food to ATP

Chemiosmosis in the Chloroplast, chemical energy is transferred from what to what?

Light to ATP

What does the Calvin Cycle use to convert CO2 to Sugar


What are the three phases in the Calvin Cycle?

1. Carbon Fixation 2. Reduction 3. Regeneration of the CO2 acceptor

On hot and dry days, what part of the Plant closes to conserve Water?


Plants are


The photosynthetic mMembranes are found in the _____ in plant cells.


In the electromagnetic spectrum, the type of radiation that we call visible light occurs between _____.

ultraviolet radiation and infrared radiation

What is the product of light reactions during photosynthesis?

NADPH, high energy electrons, oxygen, ATP

When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____.

Splitting Water

Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is_ _____ during the Calvin Cycle.

oxidized, reduced

What product is consumed during the Calvin Cycle of photosynthesis??


What is the overall function of the Calvin Cycle

Make Sugar

C4 plants occur more commonly in desert conditions because _____

they can fix carbon at the lower CO2 concentrations that develop when the stomata are closed

The Carbon fixation involves the addition of carbon dioxide to _____.


After 3-PGA is phosphorylated, it is reduced by _____.


How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?


In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?


Energized electrons from photosystem I are used to reduce what?


What part of the plant contains chlorophyll?


Stacked thylakoids are called?


Where does light reactions occur?


Where does the Calvin Cycle occur?


The light reactions of photosynthesis use _____ and produce _____.

water, NADPH

What type of plants are found in tropical grasses?


Where s CAM found


In C3 plants the conservation of water promotes _____.


In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.


C4 plants differ from C3 and CAM plants in that C4 plants _____.

transfer fixed carbon dioxide to cells in which the Calvin cycle occurs

Accessory pigments within chloroplasts are responsible for

absoring photons of different wavelengths of light and passing that energy to P680 or P700

Linear Electron flow along with chemiosmosis in the chloroplast results in the production of

ATP, NADPH, and O2

CAM plants avod photorespiration by

fixing CO2 into organic acids during the night; these acids then release CO2 during the day

What are the final electron acceptors for the ETC in the light reactions of photosynthesis and in cellular respiration?

NADP+ in light reactions, O2 in respiration

Chloroplasts can make carbs in the dark if provided with


What does the rubisco do

adds CO2 to RuBP in the carbon fixation stage

In photosynthesis, plants use carbon from _____ to make sugar and other organic molecules.

Carbon Dioxide

How does carbon dioxide enter the leaf?

Through the Stomata

In a rosebush, chlorophyll is located in _____.

thylakoids, which are in chloroplasts in the mesophyll cells of a leaf

Chlorophyll molecules are in which part of the chloroplast?


The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from _____.


In photosynthesis, what is the fate of the oxygen atoms present in CO2? They end up ______.

in sugar molecules and in water

Molecular oxygen is produced during _____.

the light reactions of photosynthesis

The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why?

The Calvin cycle depends on products of the light reactions.

The photosynthetic event known as the Calvin cycle occurs in the _____.


the wavelengths of light most effective in driving photosynthesis are referred to as _____.

The action Spectrum

Where do the electrons needed by photosystem II originate?


During photosynthesis in chloroplasts, O2 is produced from ______ via a series of reactions associated with ______.

H2O; photosystem II

Which one of the following is cycled in the cyclic part of light reactions?


Both mitochondria and chloroplasts _____.

use a hydrogen ion (proton) gradient to produce ATP

During photosynthesis in a eukaryotic cell, a high proton concentration accumulates or is formed in the ______.

(inner) thylakoid space

The light reactions of photosynthesis generate high-energy electrons, which end up in ____. The light reactions also produce ____ and ____.

NADPH ... ATP ... oxygen

The energy used to produce ATP in the light reactions of photosynthesis comes from _____.

movement of H+ through a membrane

What is the role of NADP+ in photosynthesis?

It is reduced and then carries electrons to the Calvin cycle.

In the Calvin cycle, CO2 is combined _____.

with a 5-carbon compound to form an unstable 6-carbon compound, which decomposes into two 3-carbon compounds

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