Chapter 20 Multiple Choice

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 reaction

A) are driven ultimately by the energy of sunlight.

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.

B) 12 mol of NADPH and 18 mol of ATP.

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

B) UDP-glucose and fructose 6-phosphate

The assimilation of CO2 into organic compounds (triose phosphates) in green plants: A) involves condensation of the two-carbon compound acetate with CO2 to form 3-phosphoglycerate. B) requires NADPH. C) results in the production of ATP. D) takes place at equal rates in light and darkness. E) takes place in the cytosol.

B) requires NADPH.

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.

C) It produces O2.

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

C) Mannose 6-phosphate

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

C) Phosphofructokinase-1

Penicillin inhibits the synthesis of peptidoglycan: A) branches. B) chains. C) crosslinks. D) precursors. E) all of the above.

C) crosslinks.

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.

C) ribulose 1,5-bisphosphate.

When transketolase acts on fructose 6-phosphate and glyceraldehyde 3-phosphate, the products are: A) 3-phosphoglycerate and glyceraldehyde 3-phosphate. B) 3-phosphoglycerate and two molecules of glyceraldehyde 3-phosphate. C) dihydroxyacetone phosphate and glucose 6-phosphate. D) xylulose 5-phosphate and erythrose 4-phosphate. E) xylulose 5-phosphate and ribose 5-phosphate.

D) xylulose 5-phosphate and erythrose 4-phosphate.

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

E) The urea cycle

The synthesis of glycogen and sucrose uses _________ as the substrate, rather than _________, which is used in the synthesis of starch. A) ADP-fructose; UDP-glucose B) ADP-glucose; UDP-glucose C) fructose 1-phosphate; glucose 1-phosphate D) glucose 1-phosphate; glucose 6-phosphate E) UDP-glucose; ADP-glucose

E) UDP-glucose; ADP-glucose

Transketolase requires the coenzyme: A) cobalamin (vitamin B12). B) lipoic acid C) pyridoxal phosphate. D) tetrahydrofolic acid. E) thiamine pyrophosphate.

E) thiamine pyrophosphate.