Microbiology

Chapter 8

1. What statement regarding enzymes is incorrect?

A) They can be recycled

B) They are not permanently changed by a chemical reaction

C) They increase the activation energy required for a chemical reaction to occur

D) They are composed of protein and may require cofactors

E) They act as organic catalysts

2. Which of the following is the substrate for ribozymes?

A) Proteins

B) Metal ions

C) Ribosomes

D) RNA

E) DNA

3. Metallic cofactors perform what function in enzymatic reactions?

A) They are involved in self splicing of RNA

B) They activate enzymes

C) They speed up chemical reactions

D) They perform necessary alterations to a substrate molecule

E) They serve as transient carriers of vitamins

4. What enzymes are always present in a cell at relatively constant amounts?

A) Induced enzymes

B) Exoenzymes

C) Coenzymes

D) Endoenzymes

E) Constitutive enzymes

5. What enzymes help pathogens avoid host defenses or promote their multiplication in tissue?

A) Induced enzymes

B) Exoenzymes

C) Coenzymes

D) Endoenzymes

E) Constitutive enzymes

6. Denaturation of enzymes can occur under all but which of the following conditions?

A) Low temperatures

B) High temperatures

C) Low pH

D) High pH

E) Presence of heavy metals or alcohols

7. Which molecule reacts with acetyl CoA, therefore starting the TCA cycle?

A) Alpha-ketoglutaric acid

B) Succinyl CoA

C) Oxaloacetic acid

D) Pyruvic acid

E) ATP

8. What often controls enzyme repression?

A) End-products

B) Molecular mimics

C) Substrates

D) Reactants

E) Bioenergetics

9. For the most part, what type of energy operates cell transactions?

A) Thermal

B) Electrical

C) Atomic

D) Chemical

E) Radiant

10. What is the most common electron carrier in biological systems?

A) FAD

B) Coenzyme A

C) NAD

D) NADP

E) Compounds of the respiratory chain

11. Which statement describes why ATP is an unstable high-energy molecule?

A) The purine base adenine repels the ribose

B) B- Ribose contains four carbons

C) The bond that joins the phosphate groups releases energy when it is broken

D) The absence of a hydroxyl group on the 2' carbon of the ribose allows for higher energy potential

E) The presence of a ringed sugar causes the bond between it and the phosphates to be unstable

12. What is the process by which ATP is formed through a series of oxidation-reduction reactions that occur during the final phase of respiration?

A) Photophosphorylation

B) Substrate-level phosphorylation

C) Phosphorylation

D) Oxidative phosphorylation

E) Fermentation

13. During the process of group translocation, glucose is brought into the cell and is chemically modified into what compound, which prevents it from leaving the cell?

A) Pyruvate

B) Carbon dioxide

C) ATP

D) Acetyl-CoA

E) Glucose-6-phosphate

14. The NADH molecules generated during the single oxidation-reduction reaction in glycolysis will undergo further reactions in what pathway?

A) Electron transport chain

B) The conversion step

C) Pentose phosphate pathway

D) The TCA cycle

E) Fermentation

15. In glycolysis a net gain of two ATPs are generated by what process?

A) Chemiosmosis

B) ADP processing

C) Substrate level phosphorylation

D) Electron transport

E) The splitting of a 6-carbon sugar to two 3-carbon sugars

16. Where does the TCA cycle take place in bacteria?

A) Mitochondrial matrix

B) Cytoplasm

C) Mitochondrial membrane

D) Cytoplasmic membrane

E) Nucleus

17. In aerobic respiration when is the first molecule of carbon dioxide released?

A) During chemiosmosis

B) When pyruvic acid is reduced to lactic acid

C) When glucose is phosphorylated in glycolysis

D) Following the first turn of the TCA cycle

E) During the conversion step when pyruvic acid is converted to acetyl-CoA

18. For each molecule of glucose that undergoes aerobic respiration, how many carbon dioxide molecules are released?

A) One

B) Three

C) Four

D) Six

E) Twelve

19. What is not a compound in the electron transport system?

A) NADH dehydrogenase

B) Flavoproteins

C) Coenzyme Q

D) NADPH dehydrogenase

E) Cytochromes

20. The coupling of ATP synthesis to electron transport is known as what?

A) Oxidative phosphorylation

B) Chemiosmosis

C) ATP synthesis

D) Substrate level phosphorylation

E) Proton motive force

21. Which of the following drives the synthesis of ATP by ATP synthase in oxidative phosphorylation?

A) NADH

B) Distribution of electric potential across a membrane

C) FADH

D) Cytochrome oxidase

E) Intermediate space of the mitochondria

22. What pathway is a significant intermediate source of pentoses for nucleic acid synthesis?

A) Glycolysis

B) TCA cycle

C) Electron transport chain

D) Fermentation

E) Hexose monophosphate shunt

23. Which statement regarding fermentation is incorrect?

A) Glucose is completely oxidized

B) It does not require oxygen

C) Organic compounds serve as the terminal electron acceptors

D) Only a small amount of ATP is generated

E) It yields the most varied products of the metabolism of Pyruvate

24. The souring of milk is due to the production of what compound during fermentation?

A) Ethanol

B) Lactic acid

C) Acetic acid

D) Carbon dioxide

E) Propionic acid

25. Which is not a metabolic intermediate used in amphibolic pathways?

A) Glyceraldehyde-3-phosphate

B) Acetyl CoA

C) Fructose-1,6-bisphosphate

D) Pyruvic acid

E) Oxaloacetic acid