Photosynthesis

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.

Reaction-center complex

A complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this 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.

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.

Thylakoids

A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy. The reactions take place in the thylakoid membrane.

Thylakoids

A flattened, membranous sac inside a chloroplast. Thylakoids often exist in stacks called grana that are interconnected; their membranes contain molecular "machinery" used to convert light energy to chemical energy.

Chlorophyll

A green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll 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; it has two molecules of P700 chlorophyll a at its reaction center.

Photosystems

A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes. There are two types of photosystems, I and II; they absorb light best at different wavelengths.

C4 Plants

A plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle.

CAM plants

A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions. In this process, carbon dioxide entering open stomata during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed.

C3 plants

A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.

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.

Carotenoids

An accessory pigment, either yellow or orange, in the chloroplasts of plants and in some prokaryotes. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis.

What connects the two photosystems ( I and II) 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.

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.

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

NADPH NADPH is an electron carrier that picks up electrons and hydrogen ions 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 and hydrogens produced during the light reactions.

Photo system II

One of two light-capturing units in a chloroplast's thylakoid membrane or in the membrane of some prokaryotes; it has two molecules of P680 chlorophyll a at its reaction center.

Photorespiration

Photorespiration 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. In short the oxygen binds to the enzyme that CO2 would to make the 6 carbon molecule. So, oxygen gets int he way and the Calvin cycle is short circuited.

What colors of wavelengths do the chlorophyll normally absorb

Red, Blue, and violet

Photophosphorylation

The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis. In short the hydrogen ions moving through ATP synthase helps create ATP.

Calvin cycle / Light Independent

The second of two major stages in photosynthesis (following the light reactions), involving fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate.

Describe Carbon Fixation in the Calvin Cycle(light independent)

Three molecules of carbon dioxide are added to three molecules of a five-carbon sugar abbreviated RuBP. These molecules are then rearranged to form six molecules called 3-PGA, which have three carbons each.

Chloroplasts

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

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

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

H2O Electrons are stripped from water (photolysis) 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(splits) = e- → photosystem II -ETC- photosystem I - NADPH → Calvin cycle The electron really traveled

How is photosynthesis similar in C4 plants and CAM plants?

In both cases, rubisco is not used to fix carbon initially. This means that the carbons in carbon dioxide are stored at a 4-carbon molecule. That way CO2 is available during the day so they do not have to open their stomatas during the day.

What are the two stages of photosynthesis

light dependent and light independent (Calvin)

What colors of wavelengths do the carotenoids normally absorb

Blue, Greens, and Violet

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? 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.

Where does the Calvin Cycle / light independent take place?

The Calvin cycle/ light independent 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.

Light Reactions

The first of two major stages in photosynthesis (preceding the Calvin cycle/ light independent). These reactions, which occur on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes, convert solar energy to the chemical energy of 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 (Calvin Cycle).

Carbon Fixation

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).

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

release of oxygen

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

removal of electrons from chlorophyll molecules

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

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