ABS - Chapter 11

Each of the following statements accurately describes the Calvin cycle except

*It is confined to the cytoplasm in plants and algae. Calvin Cycle: - Its products enter a variety of metabolic pathways including sugar and starch biosynthesis. - Carbon dioxide is fixed by reduction to form organic sugars. - It involves ribulose-1,5-bisphosphate (RuBP). - It is found in all oxygenic and most anoxygenic phototrophs.

Plastocyanin (PC)

- Is functionally similar to plastoquinol. - Is a mobile electron carrier. - Carries only one electron at a time. - Carries electrons to PSI.

Each of the following is part of the energy transduction from solar energy to chemical energy except

- Light absorption by chlorophyll. - Unidirectional proton pumping across a membrane. - An electrochemical proton gradient. - Electron flow through an electron transport system. *All are involved in the energy transduction.

All of the following are true regarding anoxygenic photosynthesis

- NADPH is regenerated by photoreduction. - Absorbed light energy is typically in the near ultraviolet and far-red ranges of the light spectrum. - It is a light-driven oxidation-reduction process. - Sulfide or thiosulfate can act as electron donors. *Does not split a water molecule.

Accessory pigments that can catch photons not caught by Chlorophyll

- Phycocyanin - A Phycobilin - Lutein - Beta-carotene

Part complete Which of the following statements accurately describes the Calvin cycle?

- The Calvin cycle is a means of carbon fixation. - In this process, carbon dioxide is reduced to organic sugars. - It is a carbon assimilation process. - It occurs in the chloroplast stroma.

For which of the following reasons should glucose NOT be considered a primary product of photosynthesis?

- The first reduced sugar formed is 3-phosphoglyceraldehyde (3 carbons). - Starch is the storage form of fixed carbon. - The carbon fixation reactions fix one CO2 at a time, not six. - All of the answers are correct.

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

3

The plants referred to as C3 and C4 plants get this designation based on the number of carbons in the first detectable product of carbon dioxide fixation. The C3 product is ________, whereas the C4 product is ________.

3-phosphoglycerate; oxaloacetate

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

6

Part complete Which of these equations best summarizes photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Which of the following explains why photosystem units contain a high proportion of antenna pigments compared to reaction centers?

Antenna pigments allow more wavelengths of light and more photons to be captured, increasing the efficiency of light capture.

In a chloroplast, the stroma is the

Central semifluid region

Which of the following initially traps solar energy in the process of photosynthesis?

Chlorophyll

The relationship between photosystem I (PSI) and photosystem II (PSII) is correctly described by which of the following statements?

Chlorophyll molecules in the reaction centers of PSI and PSII are designated P700 and P680, respectively, to reflect the wavelengths of their light absorption maxima.

Which of the following is not an essential feature of electron transfer from water to NADP+?

Coenzyme Q Essential features: Cytochrome b6/f complex. PSI. PSII. plastocyanin (PC).

Biosynthesis of sucrose occurs in the

Cytoplasm

Biosynthesis of sucrose occurs in the

Cytosol

Which of the following minerals are directly involved with light absorption in photosynthesis?

Mg

A house plant seems to be growing slowly and lacks its normal bright green color. You call a botanist for advice. She suggests that the plant may be deficient in magnesium (Mg2+). Why are these symptoms associated with Mg2+ deficiency?

Mg2+ is an important component in chlorophyll.

Which of the following statements correctly characterizes the relationship between NADP+/NADPH and NAD+/NADH?

NADP+/NADPH has an extra phosphate compared to NAD+/NADH.

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

NADPH

Which of the following molecules is the primary product of photosystem I?

NADPH

Which of the following statements is correct regarding cyclic photosynthetic pathways?

No exogenous electron source is required.

The relationship between photosystem I (PSI) and photosystem II (PSII) is correctly described by which of the following statements?

PSI is designated P700, whereas PSII is designated P680.

Which of the following products cannot be used in the Calvin cycle?

Phosphoglycolate

Part complete The process by which photosynthetic organisms use light energy for ATP production is known as

Photophosphorylation

Which process produces oxygen?

Photosynthesis

Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose?

Regeneration of RuBP

The transfer of energy from a photoexcited electron to another electron of an adjacent pigment molecule is known as

Resonance energy transfer

NADPH contains the pentose sugar ________ and the nitrogenous base ______

Ribose, Adenine

Carbon fixation involves the addition of carbon dioxide to _____.

RuBP

Carbon dioxide generally enters the plant through pores called

Stomata

The Calvin cycle occurs in the ________ region of the chloroplast.

Stroma

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 ATP and NADPH, which are most readily available from the light reactions.

Which set of reactions uses H2O and produces O2?

The light-dependent reactions

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?

The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?

The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.

What is the biological significance of the light-independent reactions of photosynthesis?

They convert carbon dioxide to sugar.

In a chloroplast, the stroma is

a gel-like matrix between the inner chloroplast membrane and the thylakoid membrane.

When a photon is absorbed by a pigment (light-absorbing molecule), such as chlorophyll, the energy of the photon is transferred to

an electron to move it from a low to a high energy orbital.

Most reactions involving NADP+ are ________ reactions, whereas most reactions involving NAD+ are ________ reactions.

anabolic; catabolic

NADP+ is the coenzyme of choice in ________ reactions, while NAD+ is the coenzyme of choice in ________ reactions.

anabolic; catabolic

Which two triose phosphates are produced during the Calvin cycle and are the starting points for starch and sucrose synthesis?

dihydroxyacetone phosphate and glyceraldehyde-3-phosphate

Which of the following enzymes represents the link between the light and dark reactions of photosynthesis?

ferredoxin-NADP+ reductase

Photoheterotrophs are best described as organisms that obtain energy to make ATP

from sunlight but cannot make organic compounds from CO2

Which molecule in the Calvin cycle is used to synthesize starch and sucrose?

glyceraldehyde-3-phosphate

The NADPH required for CO2 fixation is produced __________.

in direct proportion to the amount of O2 produced

Plastocyanin (PC)

is a mobile electron carrier and carries only a single electron at a time.

The ATP synthase complex in the thylakoid membrane

performs photophosphorylation in oxygenic phototrophs.

Part complete Based upon the comparisons of anoxygenic and oxygenic photosythesis, the entry of oxygen into the atmosphere is most directly attributed to

photosystem II

Plastoquinol transfers electrons from

photosystem II to photosystem I.

Which is the correct order of flow of electrons through the thylakoid membrane during energy transduction reactions?

photosystem II, cytochrome complex, photosystem I

Which process in photosynthesis will be most directly compromised by inhibition of the cytochrome b6f complex?

proton pumping

The endosymbiotic theory states that mitochondria originated from

purple bacteria entering and remaining in the cytoplasm of another cell.

Part complete In the Calvin cycle, the enzyme that catalyzes the capture of carbon dioxide and the formation of 3-phosphoglycerate is

ribulose bisphosphate carboxylase/oxygenase (rubisco).

The regeneration of what CO2 acceptor molecule allows for continuous carbon assimilation in the Calvin cycle?

ribulose-1,5-bisphosphate

In the Calvin cycle, the enzyme that catalyzes the capture of carbon dioxide and the formation of 3-phosphoglycerate is

ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco).

The light reactions of photosynthesis use _____ and produce _____.

water ... NADPH