BIO104 - Fotosyntese

What are the two photosystems involved in photosynthetic electron transport?

Question

Photosystem II and Photosystem I

Answer

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Mariel

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Questions in this set (96)

What are the two photosystems involved in photosynthetic electron transport?

Photosystem II and Photosystem I

What is the reaction center of Photosystem II?

P680

What is the first learning outcome for students regarding photosynthesis?

Understand physical principles behind photosynthetic energy storage

What is the reaction center of Photosystem I?

P700

What is the second learning outcome for students regarding photosynthesis?

Good understanding of the structure and function of the photosynthetic apparatus

What is the role of the primary electron acceptor?

Accepts electrons

What is the third learning outcome for students regarding photosynthesis?

Use light energy to drive synthesis of carbohydrates and oxygen

Which complex facilitates electron transfer between Photosystem II and Photosystem I?

Cytochrome complex

What is Pq?

Plastoquinone

What is Fd?

Ferredoxin

What is the fourth learning outcome for students regarding photosynthesis?

Explain the structural difference between photosynthetic apparatus

In what part of the leaf does photosynthesis occur?

Mesophyll

What is Pc?

Plastocyanin

What organelle performs photosynthesis?

Chloroplast

What structure allows CO2 and O2 to enter/exit the leaf?

Stomata

Which enzyme catalyzes the transfer of electrons to NADP+?

NADP+ reductase

What is the final electron acceptor in the electron transport chain?

NADPH

What molecule is split to replenish electrons in Photosystem II?

Water is split

What are the three main membrane structures of the chloroplast?

Outer membrane, intermembrane space, inner membrane

What gas is produced during the splitting of water in photosynthesis?

Oxygen

What type of light is used for photosynthesis?

Absorbed light

In cyclic electron flow, where do electrons cycle back from?

Fd to PS I via Pc

Name three chloroplast pigments.

Chlorophyll a, Chlorophyll b, Carotenoids

Which photosystem is used in cyclic electron flow?

Photosystem I

What is the light-absorbing head of a chlorophyll molecule called?

Porphyrin ring

What energy molecule is produced in cyclic electron flow?

ATP

What atom is at the center of the porphyrin ring?

Magnesium

Is oxygen released during cyclic electron flow?

No

What part of the chlorophyll interacts with hydrophobic regions of proteins?

Hydrocarbon tail

When is cyclic electron flow thought to have evolved?

Before linear electron flow

Where are the hydrophobic regions of proteins located?

Thylakoid membranes

What does cyclic electron flow protect cells from?

Light-induced damage

What cycle does NADPH feed into?

Calvin cycle

What is the emission of light by a substance that has absorbed light or other electromagnetic radiation called?

Fluorescence

Where are the protein subunits located?

Stroma

Where is the high H+ concentration during ATP production?

Thylakoid space

What complex contains a special pair of chlorophyll a molecules?

Reaction-center complex

Where is the low H+ concentration during ATP production?

Stroma

What photosystem is associated with P680?

Photosystem II

Which enzyme uses the H+ gradient to produce ATP?

ATP synthase

What photosystem is associated with P700?

Photosystem I

From which photosystem to which does electron flow pump H+ into the thylakoid space?

PSII to PSI

What process does ATP synthase drive using the energy in the H+ gradient?

Phosphorylation of ADP

What reactions produce ATP and NADPH?

Light reactions

What cycle uses ATP and NADPH?

Calvin cycle

How many CO2 molecules enter the Calvin cycle per cycle?

3

Which enzyme is involved in carbon fixation in the Calvin cycle?

Rubisco

What are the three phases of the Calvin cycle?

Carbon fixation, reduction, regeneration

What molecule is regenerated in the third phase of the Calvin cycle?

RuBP

What is the output of the reduction phase of the Calvin cycle?

G3P

What is G3P used to produce?

Glucose and other organic compounds

Which enzyme initially fixes CO2 in C4 and CAM plants?

PEP carboxylase

What sugar does carbon leave the Calvin cycle as?

Glyceraldehyde 3-phosphate (G3P)

What are the CO2 and O2 affinities of PEP carboxylase?

High affinity to CO2, none to O2

In which types of plants is CO2 re-fixed by Rubisco after initial fixation?

C4 and CAM plants

How many times must the Calvin cycle take place for net synthesis of one G3P?

Three

How many molecules of CO2 are fixed during the Calvin cycle for net synthesis of one G3P?

Three

Is the Calvin cycle anabolic or catabolic?

Anabolic

What benefit do C4 and CAM pathways provide to plants in terms of water conservation?

Close stomata and avoid photorespiration

What does the Calvin cycle build from smaller molecules?

Builds sugar from smaller molecules

In C4 plants, where does the initial fixation of CO2 by PEP carboxylase occur?

Mesophyll cells

What two energy-carrying molecules are used by the Calvin cycle to build sugar?

ATP and NADPH

What can Rubisco add instead of CO2?

Adds O2 instead of CO2

In C4 plants, where is CO2 released and re-fixed by Rubisco?

Bundle sheath cells

Give examples of C4 plants.

Maize, sugar cane, many grasses

What percentage of flowering plant species are C4 plants?

3%

What process occurs when Rubisco adds O2 instead of CO2?

Photorespiration

What percentage of global primary production is attributed to C4 plants?

23%

How many times has the C4 pathway evolved?

Multiple times

What are the products and energy usage of photorespiration?

CO2 and ammonia released, ATP used, no sugar produced

What do plants do on hot, dry days to conserve H2O, which also reduces access to CO2?

Close stomata

What does CAM stand for?

Crassulacean acid metabolism

What do warmer chloroplasts dissolve less of?

Less CO2

During which part of the day do CAM plants open their stomata?

Night

Where are organic acids stored in CAM plants?

Vacuoles

During which part of the day do CAM plants close their stomata?

Day

What were the atmospheric conditions when Rubisco first evolved?

Less O2, more CO2

Give examples of CAM plants.

Pineapple, cacti, orchids

What does photorespiration limit in the absence of the Calvin cycle?

Limits damaging products of light reactions

How much of the carbon fixed by the Calvin cycle can photorespiration drain on a hot, dry day?

50%

In what types of environments are CAM plants often found?

Epiphytes and succulent xerophytes

What percentage of flowering plant species are CAM plants?

7%

How many times has the CAM pathway evolved?

Multiple times

What are the two stages of photosynthesis?

Light reactions and Calvin cycle

Where do the light reactions of photosynthesis take place?

Thylakoids

Where does the Calvin cycle take place?

Stroma

What are the four major events of the light reactions?

Split H2O, release O2, reduce NADP+ to NADPH, generate ATP from ADP

What are the two main functions of the Calvin cycle?

Incorporates CO2 into organic molecules and forms sugar from CO2

In photosynthesis, is H2O oxidized or reduced?

Oxidized

In photosynthesis, is CO2 oxidized or reduced?

Reduced

Is photosynthesis an endergonic or exergonic process?

Endergonic

What provides the energy boost for photosynthesis?

Light

In the photosynthesis reaction, is water oxidized or reduced?

Oxidized

In photosynthesis, where does the oxygen come from?

Water (H2O)

What adaptation do C4 plants like sugarcane use to minimize photorespiration?

Spatial separation of steps

What is the name of the photosynthetic adaptation used by pineapples?

CAM