Ch. 14 Smartwork (Exam 3)

The generation of ATP by oxidative phosphorylation differs from the way ATP is produced during

glycolysis in that it requires a membrane-bound compartment (like mitochondria)

What processes require a membrane?

• generation of ATP by photosynthesis in plants

• generation of ATP by oxidative phosphorylation

• generation of ATP by photosynthesis in bacteria

• generation of energy by mitochondria

In the ETC, as electrons move along a series of carriers, they release energy that is used to do what?

pump protons across a membrane

Electrons from plastoquinone enter the ETC, which pumps protons into

the thylakoid lumen. The proton gradient is used to produce ATP via chemiosmosis

What is true of the organelles that produce ATP in eukaryotic animal cells?

they evolved from bacteria engulfed by ancestral cells billions of years ago

The absorbance range of B-carotene has the greatest overlap with the short-wavelength peak of

chlorophyll a

In stage 1 of photosyntehsis,

the movement of electrons along an ETC is used to generate a proton gradient that can be used by ATP synthase to produce ATP

Stage 1 of photosynthesis is for the most part equivalent to what process?

oxidative phosphorylation

In the ETC in chloroplasts, which molecule serves as the final electron acceptor?

NADP+

What is able to boost electrons to the very high energy level needed to make NADPH from NADP+?

photosystem I

Light absorbed by the second photosystem in the ETC (called photosystem I) boosts an

electron to the very high energy level needed to produce NADPH from NADP+

In photosynthesis, what drives the generation of ATP by ATP synthase?

a proton gradient across the thylakoid membrane

The movement of electrons along the photosynthetic ETC pumps protons across the

thylakoid membrane; this proton gradient drives the production of ATP by ATP synthase

Electrons that are excited within photosystem I are ultimately passed to

NADP+ to form NADPH

During stage I of photosynthesis, excited electrons move in which direction?

from the chlorophyll special pair to an electron carrier to NADP+

Photosystem II passes electrons to the mobile carrier

plastoquinone, which transfers them to the only proton pump involved in the photosynthetic ETC

Photosystem I boosts electrons to the

very high energy level needed to reduce NADP+ to NADPH

The water-splitting enzyme contains a cluster of

manganese atoms that holds onto two water molecules from which electrons are extracted one at a time

• once four electrons have been removed from these H2O molecules, O2 is released

During photosynthesis, what happens in the water-splitting step?

it generates essentially all of the O2 in the Earth’s atmosphere

The water-splitting enzyme that generates essentially all of the O2 in our atmosphere is associated ith

photosystem II

The enzyme ribulose bisphosphate carboxylase (Rubisco) catalyzes the carbon fixation step of the

Calvin cycle, covalently attaching carbon dioxide to ribulose 1,5-bisphosphate

What is true of the process of combining CO2 and H2O to make a carbohydrate?

it’s energetically unfavorable

What provides the fuel to convert CO2 into sugars in chloroplasts?

ATP and NADPH generated in the photosynthetic light reactions

What is true of the carbon-fixation (Calvin) cycle?

• it requires CO2

• it requires NADPH and ATP

• it requires energy-rich ribulose 1,5-bisphosphate

• it regenerates energy-rich ribulose 1,5-bisphosphate

ATP and NADPH provide the energy and reducing power needed to regenerate

ribulose 1,5-bisphosphate (the energy-rich moplecule with which CO2 is combined in the 1st step of the Calvin cycle)

For every 3 molecules of CO2 that enter the carbon-fixation cycle, what is produced and what is consumed?

1 molecule of glyceraldehyde 3-phosphate is produced, and 9 molecules of ATP + 6 molecules of NADPH are consumed

Starch is a storage polymer of glucose that is stored in

granules within the chloroplast and is broken down into fats and sugars as needed by the plant

During very active periods of photosynthesis, the glyceraldehyde 3-phosphate generated by carbon fixation in the chloroplast stroma is stored as which molecule?

starch

How can the glyceraldehyde 3-phosphate produced in the carbon fixation cycle be used?

• it can be converted into fat and stored in the chloroplast stroma

• it can be consumed by the carbon-fixation cycle to produce ribulose 1,5-bisphosphate

• it can be converted into starch and stored in the chloroplast stroma

When a chlorophyll molecule captures light energy, what form does the energy take?

excitation of electrons in the porphyrin ring

When light energy is absorbed, it excites electrons in the

bond network within the porphyrin ring of chlorophyll

During photosynthesis, charge separation takes place when what occurs?

the special pair passes an electron to an electron carrier in the reaction center, leaving behind a positive charge

In an anetenna complexc, hundreds of chlorophyll molecules are arranged so that the light energy captured by one chlorophyll molecule can jump from

one chlorophyll molecule to another within the network

What is true of the antenna complex of a photosystem?

it captures light energy

Once excited by sunlight, chlorophylls in the antenna complex do what?

transfer the energy to the chlorophyll special pair

In stage 2 of photosynthesis, which begins in the stroma, the ATP and NADPH produced in stage 1 are used to

drive the manufacture of glyceraldehyde 3-phosphate from CO2

What is true of stage 2 photosynthesis?

it produces glyceraldehyde 3-phosphate in the stroma

The enzymes that carry out the carbon-fixation cycle are located in

the chloroplast stroma

• this process does NOT require use of a membrane

In eukaryotic cells, where does the conversion of CO2 and H2O to sugar take place?

chloroplast stroma

Photosynthesis allows plants to capture energy from sunlight to produce what?

sugars

• process occurs in chloroplasts

In chloroplasts, the pigment chlorophyll donates electrons to an ETC in which cellular compartment?

thylakoid membrane

Chlorophyll molecules absorb which color of light most strongly?

red and blue

• absorb green light poorly

During Earth’s history, with the rise of cyanobacteria, what molecule began accumulating in the atmosphere for the first time?

O2

Oxygen is the final electron acceptor in

aerobic cell respiration

• the process that allows the complete breakdown of organic molecules into CO2 and H2O

What electron acceptor allows an organism to completely breakdown organic molecules into CO2 and H2O and thereby release a large amount of energy that can be harnessed by the cell to do work?

O2

What is true of nitrogen fixation?

it reduces N2 to ammonia (NH3)

The first stage of photosynthesis produces

ATP and NADPH using an ETC, proton pumping, and ATP synthesis just as in oxidative phosphorylation

The high energy electrons come from the chlorophyll special pair that has captured

energy from sunlight and transfers it via electron carrier to the ETC