Chapter 20 Carbohydrate Biosynthesis in Plants and Bacteria and 19 B (Biochem) Flashcards

The compound that condenses with CO2 in the first reaction of carbon dioxide assimilation is:

A) 3-phosphoglycerate.
B) ribose 1,5-bisphosphate.
C) ribulose 1,5-bisphosphate.
D) ribulose 5-phosphate.
E) rubisco.

Which of these enzymes is not part of the Calvin cycle?

A) Aldolase
B) Glyceraldehyde 3-phosphate dehydrogenase
C) Phosphofructokinase-1
D) Ribulose-5-phosphate kinase
E) Transketolase

Which of these compounds is not directly involved in the Calvin cycle?

A) Erythrose 4-phosphate
B) Glyceraldehyde 3-phosphate
C) Mannose 6-phosphate
D) Ribulose 5-phosphate
E) Sedoheptulose 7-phosphate

In the carbon assimilation (“dark”) reactions of photosynthesis, the biosynthesis of 1 mol of hexose
from 6 mol of carbon dioxide requires:

A) 12 mol of NADPH and 12 mol of ATP.
B) 12 mol of NADPH and 18 mol of ATP.
C) 18 mol of NADPH and 12 mol of ATP.
D) 18 mol of NADPH and 18 mol of ATP.
E) no NADPH and 12 mol of ATP.

The known mechanisms of activation of rubisco or of other enzymes of the Calvin cycle during illumination include all of the following except:

A) increased stromal pH.
B) light-driven entry of Mg2+ into the stroma.
C) phosphorylation by cAMP-dependent protein kinase.
D) phosphorylation of phosphoenolpyruvate carboxylase.
E) reduction of a disulfide bridge by thioredoxin.

The carbon assimilation (“dark”) reactions of photosynthetic plants:

A) are driven ultimately by the energy of sunlight.
B) are important to plants, but ultimately of little significance for bacteria and animals.
C) cannot occur in the light.
D) yield (reduced) NADH.
E) yield ATP, which is required for the light reactions.

All are true of photorespiration except:

A) It is driven by light.
B) It oxidizes substrates to CO2.
C) It produces O2.
D) It results from a lack of specificity of the enzyme rubisco.
E) It results in no fixation of carbon.

The three subcellular organelles involved in the phosphoglycolate salvage pathway are:

A) endoplasmic reticulum, chloroplast, and mitochondrion.
B) nucleus, endoplasmic reticulum, and chloroplast.
C) golgi apparatus, chloroplast, and mitochondrion.
D) mitochondrion, peroxisome, and chloroplast.
E) peroxisome, endoplasmic reticulum, and chloroplast.

In “C4” plants of tropical origin, the first intermediate into which 14CO2 is fixed is:

A) aspartate.
B) phosphoenolpyruvate.
C) oxaloacetate.
D) malate.
E) 3-phosphoglycerate.

The synthesis of glycogen, starch, and sucrose all:

A) involve addition of a sugar residue at the reducing end of the growing polymer.
B) take place in liver and muscle of mammals.
C) use a sugar nucleotide as substrate.
D) use glucose 1-phosphate as the only substrate.
E) use glucose-6-phosphate as substrate.

The precursors for sucrose biosynthesis are:

A) glucose and fructose
B) UDP-glucose and fructose 6-phosphate
C) UDP-fructose and glucose 6-phosphate
D) UDP-glucose and fructose
E) UDP-glucose and UDP-fructose

Which one of the following reactions, cycles, or pathways is not found in plant systems?

A) The Calvin cycle
B) The gluconeogenesis pathway
C) The glyoxalate cycle
D) The rubisco reaction
E) The urea cycle

When glycerol is converted to glucose via gluconeogenesis in germinating seeds, the first glycolytic
intermediate formed is:

A) 1,3-bisphosphoglycerate.
B) dihydroxyacetone phosphate.
C) glycerol 1,3-bisphosphate.
D) glycerol 3-phosphate.
E) ribulose 1,5-bisphosphate.

Oxidative phosphorylation and photophosphorylation share all of the following except:

A) chlorophyll.
B) involvement of cytochromes.
C) participation of quinones.
D) proton pumping across a membrane to create electrochemical potential.
E) use of iron-sulfur proteins.

The experimental determination of the effectiveness of light of different colors in promoting
photosynthesis is called the:

A)absorption spectrum.
B) action spectrum.
C) difference spectrum.
D)reflectance spectrum.
E) refraction spectrum.

In what order do the following five steps occur in the photochemical reaction centers?

1) Excitation of the chlorophyll a molecule at the reaction center
2) Replacement of the electron in the reaction center chlorophyll
3) Light excitation of antenna chlorophyll molecule
4) Passage of excited electron to electron-transfer chain
5) Exiton transfer to neighboring chlorophyll

A) 1-2-3-4-5
B) 3-2-5-4-1
C) 3-5-1-4-2
D) 4-2-3-5-1
E) 5-4-3-2-1

Which one of the following is true about reaction centers?

A) Cyanobacteria and plants have two reaction centers arranged in tandem.
B) Cyanobacteria contain a single reaction center of the Fe-S type.
C) Plant photosystems have a single reaction center of the FeS type.

In the photolytic cleavage of water by the oxygen-evolving complex [2H2O  4 H+ + 4e– + O2], how many photons of light at a wavelength of 680 nm are required?

A) 1
B) 2
C) 4
D) 6
E) 8

Photosynthetic phosphorylation and oxidative phosphorylation appear to be generally similar
processes, both consisting of ATP synthesis coupled to the transfer of electrons along an
electron carrier chain. Which of the following is not true of both processes?

A) Both contain cytochromes in their electron carrier chains.
B) Both processes are associated with membranous elements of the cell.
C) Both use oxygen as a terminal electron acceptor.
D) Both produce ATP by ATP synthase.
E) Protons are pumped from the inside to the outside of both mitochondria and chloroplast
membranes

The light reactions in photosynthetic higher plants:

A) do not require chlorophyll.
B) produce ATP and consume NADH.
C) require the action of a single reaction center.
D) result in the splitting of H2O, yielding O2.
E) produce secondary light emission so that plants can grow underground.

Which of the following statements about the light reactions in photosynthetic plants is false?

A) A membrane-bound ATPase couples ATP synthesis to electron transfer-mediated proton
trasnport.
B) (Plasto)quinones, hemes and iron-sulfur cluster mediate electron transport.
C) O2 is consumed.
D) The ultimate source of electrons for the process is H2O.
E) There are two distinct photosystems, linked together by an electron transfer chain.

Absorption of light energy in chloroplast “light reactions” leads to:

A) collapse of a proton gradient.
B) absorption of O2 and release of CO2.
C) hydrolysis of ATP and reduction of NADP+
D) production of a proton concentration gradient across thylakoid membrane
E) release of phosphate.