Photosynthesis

Describe a chlorophyll molecule

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Carbon Fixation

(Calvin Cycle) The initial incorporation of carbon from CO2 into an organic compound. RuBisCO takes RuBP and CO2 and forms an intermediate molecule The intermediate molecule is separated into two 3-carbon molecules called 3-phosphoglycerate (3PG). RuBP + CO2 = 2(3PG).

10.3 The Calvin Cycle uses the chemical energy of ATP and NADPH to reduce CO2 to sugar

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Photosynthesis converts light energy to the chemical energy of food

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Which of the following equations represents photosynthesis? 6CO2 + 6O2 → C6H12O6 + 6H2O 6H2O + 6O2 → C6H12O6 + 6CO2 C6H12O6 + 6O2 → 6CO2 + 6H2O C6H12O6 + 6CO2 → 6O2 + 6H2O 6CO2 + 6H2O → C6H12O6 + 6O2

6CO2 + 6H2O → C6H12O6 + 6O2 Photosynthesis requires carbon dioxide and water for the production of sugar and oxygen.

Thylakoids

A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy.

Light harvesting complex

A complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reaction-center pigments in a photosystem.

Chlorophyll

A green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll a participates directly in the light reactions, which convert solar energy to chemical energy.

Photosystem I

A light-capturing unit in a chloroplast's thylakoid membrane or in the membrane of some prokaryotes

Photosystem

A light-capturing unit located in the thylakoid membrane of the chloroplast There are two types of photosystems, I and II; they absorb light best at different wavelengths.

What is photorespiration?

A respiratory process by which /some/ plants take up oxygen in the light and give out some carbon dioxide, contrary to the general pattern of photosynthesis.

Glyceraldehyde 3-phosphate (G3P)

A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis.

What two molecules are produced by the light reactions and used to power the Calvin cycle? CO2 and O2 C6H12O6 and O2 C6H12O6 and RuBP ATP and NADPH G3P and H2O

ATP and NADPH ATP and NADPH are both products of the light reactions and are used to power the Calvin cycle.

The light reactions of photosynthesis supply the Calvin cycle with

ATP and NADPH.

What connects the two photosystems in the light reactions? Chlorophyll A thylakoid An electron transport chain A chain of glucose molecules The Calvin cycle

An electron transport chain

Heterotrophs

An organism that obtains organic food molecules by eating other organisms or substances derived from them.

Which of the following statements is a correct distinction between autotrophs and heterotrophs? Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic. Only heterotrophs require oxygen. Cellular respiration is unique to heterotrophs. Only heterotrophs have mitochondria. Only heterotrophs require chemical compounds from the environment.

Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

Photorespiration

C6H12O6 + 6O2 --> 6CO2 + 6H2O Generally occurs on hot, dry, bright days, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco.

What are the three phases of The Calvin cycle?

Carbon Fixation Energy Consumption and Redox Release of G3P; Regeneration of RuBP

What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle? What happens? Sucrose (C12H22O11) RuBP Carbon dioxide (CO2) Glucose (C6H12O6) G3P (C3H6O3)

Carbon dioxide (CO2) Carbon dioxide provides the carbon atoms that are incorporated into sugars in photosynthesis. Carbon dioxide initially combines with RuBP, and RuBP is regenerated to continue the Calvin cycle.

In which of the following organelles does photosynthesis take place? Chloroplast Mitochondrion Ribosome Central vacuole Nucleus

Chloroplast Chloroplasts use energy from light to transform carbon dioxide and water into sugar and oxygen.

Where does photosystem II take place?

Chloroplast's thylakoid membrane or in the membrane of some prokaryotes

What provides electrons for the light reactions? CO2 The Calvin cycle H2O Light O2

H2O Electrons are stripped from water in the light reactions of photosynthesis. Light provides the energy to excite electrons.

Which of the following sequences correctly represents the flow of electrons during photosynthesis? NADPH → chlorophyll → Calvin cycle H2O → NADPH → Calvin cycle NADPH → O2 → CO2 NADPH → electron transport chain → O2 H2O → photosystem I → photosystem II

H2O → NADPH → Calvin cycle

How is photosynthesis similar in C4 plants and CAM plants?

In both cases, rubisco is not used to fix carbon initially.

C3 plants

In the Calvin cycle, the first product that results from carbon fixation is 3-phosphoglycerate. C3 plants close their stomata on hot, dry days to limit water loss, making the concentration of CO2 in the leaf fall, which causes the Calvin cycle to slow down

Primary electron acceptor

In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecules and that accepts an electron from them.

What transports electrons from the light reactions to the Calvin cycle? NADH NADPH An electron transport chain FADH2 Chlorophyll

NADPH NADPH is an electron carrier that picks up electrons in the light reactions and releases them in the Calvin cycle. An electron transport chain conveys electrons from one photosystem to the other within the light reactions.

NADP

Nicotinamide adenine dinucleotide phosphate, an electron acceptor that, as NADPH, temporarily stores energized electrons produced during the light reactions.

What is the difference between photoautotrophs, chemoautotrophs, and heterotrophs?

Photo and chemo are producers, which get their energy from the environment, but photo releases O2 while chemo doesn't Heterotrophs are consumers

What are the two stages of photosynthesis

light dependent and light independent

CAM plants

SUCCULENT PLANTS IN ARID CONDITIONS CAM plants open their stomata during the night. Perform the reverse of regular plants for photosynthesis - light reactions are performed during the night while the dark reactions are carried out during the day. During the night, CO2 entering open stomata is converted to organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed.

C4 Plants

TROPICAL PLANTS Incorporates CO2 into a four-carbon compound. Open their stomata during the day. The end product supplies CO2 for the Calvin cycle.

Where does the Calvin Cycle take place?

The Calvin cycle is a complex series of chemical reactions carried out in the stroma.

Photosynthesis

The conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes. 6 H2O + 6 CO2 + solar energy --> 6 O2 + C6H12O6

Light Reactions

The first of two major stages in photosynthesis (preceding the Calvin cycle). occur on the thylakoid membranes of the chloroplast convert solar energy to ATP and NADPH, releasing oxygen in the process.

Stroma

The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.

Photophosphorylation

The process of generating ATP from ADP and phosphate using a proton concentration gradient across the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.

Calvin cycle

The second of two major stages in photosynthesis (following the light reactions) Occurs in the stroma NADPH and ATP from the light reactions fix CO2 to create a new glucose molecule ADP and NADP+ get recycled

Describe Carbon Fixation in the Calvin Cycle

Three molecules of carbon dioxide are added to three molecules of the five-carbon sugar RuBP. These molecules are then rearranged to form six molecules of three-carbon 3-PGA

Reaction-center complex

Triggers the light reactions of photosynthesis. Excited by light energy, the pair of chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain.

Chloroplasts

absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water.

Which process is most directly driven by light energy? a. creation of a pH gradient by pumping protons across the thylakoid membrane b. removal of electrons from chlorophyll molecules c. reduction of NADP+ molecules d. ATP synthesis e. carbon fixation in the stroma

b. removal of electrons from chlorophyll molecules

Thylakoids

folded membrane within the stroma Contains pigments that absorb light Light-dependent reactions occur here (ATP, NADPH formed)

In mechanism, photophosphorylation is most similar to

oxidative phosphorylation in cellular respiration.

Stomata

pores on the leaf where O2 exits and CO2 enters

Autotrophic

produce their organic molecules from CO2 and other raw material from the environment.

Autotrophs

produce their own organic molecules from CO2

Which of the following does not occur during the Calvin cycle? release of oxygen regeneration of the CO2 acceptor oxidation of NADPH consumption of ATP carbon fixation

release of oxygen

The light reactions take place in the _________ and the Calvin cycle takes place in the _________. stroma; thylakoids thylakoids; stroma inner membrane; outer membrane chloroplasts; mitochondria mitochondria; chloroplasts

thylakoids; stroma Within the chloroplast, the light reactions take place in the flattened sacs called thylakoids and the Calvin cycle takes place in the thick fluid called the stroma.