Questions

1. Phosphorylation of glucose by hexokinase does not contribute to:-

a) Escaping of glucose molecule out of cell.

b) Binding energy of phosphohexose isomerase.

c) Activation of glucose molecule.

d) Net negative free energy change.

2. Inhibition of Triose phosphate isomerase results in net formation of how many ATP from 1 molecule of glucose in glycol sis:

a) 4 b) 2 c) 0 d) 1

3. During glycolysis, 1 molecule of glucose yield how many molecules of H₂O:

a) 1 b) 2 c) 4 d) 0

4. During vigorous exercise, inhibition of lactate dehydrogenase in muscle does not result in:

a) High [NAD⁺] level b) lowering of pH

[NADH]

c) Inhibition of glycoysis d) shifting of equilibrium of bicarbonate buffer toward left

5. How many steps of glycolysis are endergonic in nature:-

a) 4 b) 6 c) 3 d) 2

6. The methyl group of pyruvate is formed from which carbon of glucose

a) 1 and 6 b) 2 and 5 c) 3 and 4 d) 2 and 4

7. If all the oxygen atoms of glucose were radioactively labeled, how many oxygen atom of pyruvat would be radioactive.

a) 3 b) 2 c) 1 d) None

8. Decyclization occurs in which step of glycolysis.

a) 5 b) 4 c) 3 d) 6

9. The phosphate group of glucose – 6 – phosphate is used in substrate level phosphorylation in step no. :

a) 7 b) 6 c) 10 d) 9

10. Which carbon of glucose occur in reduced state in pyruvate

a) 1 and 6 b) 2 and 5 c) 3 d) 4

11. Mannose enters glycolysis after it is converted to:

a) glycose – 6 – phosphate b) Fructose – 6 – phosphate

c) Fructose 1, 6 bisphosphate d) glucose – 1 – phosphate

12. UMP donor during conversion of galactose 1 – phosphate to UDP – glactose is

a) UTP b) UDP c) UDP – glucose d) UDP – mannose

13. No. of NADH consumed during conversion of 1 molecule of galactose to 2 molecule of pyruvate

a) 2 b) 1 c) 0 d) 3

14. Production of ethanol is inhibited by:

a) High [NADH] ratio b) presence of Mg²⁺

[NAD ⁺]

c) High CO₂ level d) presence of O₂

15. Which carbon of glucose is released as CO₂ during ethanol production?

a) 4 and 3 b) 1 and 6 c) 2 and 5 d) 3 and 5

16. Which enzymes doesn’t require Thiamine pyrophosphate

a) Pyruvate dehydcogenase b) pyruvate decarboxylase

c) Transketolase d) Succinate dehydrogenase

17. No. of ATP equivalents used in formation of 1 molecule of glucose from 2 molecule of pyruvate is

a) 4 b) 5 c) 6 d) 8

18. the most exergonic step during gluconeogenesis is

a) 1^st b) 2^nd c) 5^th d) 9^th

19. After 3 molecules of glucose – 6 – phosphate enter pentose phosphate pathway, how many molecules of CO₂ is liberated

a) 6 b) 3 c) 0 d) None

20. Defect in pentose phosphate pathway causes:-

a) Bromolecules damage by superoxide radical b) Reduced nucleotide, RNA, DNA brosynthesis

c) Both a & b d) Only a

21. Transketolase transfer how many carbon

a) 1 b) 2 c) 3 d) 4

22. Transaldolase transfer how many carbon

a) 1 b) 2 c) 3 d) 4

23. Which ractive species causes maximum damage to biomolecules

a) O₂ b) H₂O₂ c) OH^- d) OH

24. How many net ATP is used in converting glucose to pyruvate and pyruvate black to glucose.

a) 2 b) 4 c) 6 d) 8

25. Significance of lactate formation is/are

a) Prevent halting of glycolysis b) provede substrate for gluconeogenesis in liver

c) Increase [NAD⁺] ratio d) All

[NADH]

26. The final catabolic product of glucose in RBC is:

a) CO2 & H2O b) Pyruvate & lactafe c) Both a & b

27. The energy yielding pathway in RBC is

a) TCA cycle b) glycolysis c) both a & b d) pentose phosphate pathway

28. In cancerous cell much of ATP is formed by

a) TCA cycle b) glycolysis c) electron transport change d) Both a & b

29. The reactive intermediate in thiamine pyrophosphate catalysed reaction is

a) Carbocation b) Carbanion c) free radical d) All

30. In anaerobic process, there is …………………………………..of the carbons of glucose.

a) net oxidation b) net reduction c) no net oxidation or reduction

31. (α 1 → 6) glucosidase activity of debranching enzyme produce

a) glucose 1 – phosphate b) glucose – 6 – phosphate c) glucose d) glucose 1, 6 bisphosphate

32. The active residue in the phosphoglucomutase enzyme that catalyse the reaction is

a) Serine b) Threonine c) phosphorylated serine d) phosphorylated threonine

33. Glucose transporter in liver is

a) GLUT 4 b) GLUT 2 c) GLUT 1 d) All

34. Inhibition of Pi (inorganic phosphate) transporter at Endoplasmic reticulum of liver cell results in

a) Decrease level of glucose transport from liver to blood.

b) Lowers ATP concentration in liver cytosol

c) Decrease the activity of glyceraldehye 3 – phosphate dehydrogenase enzyme.

d) All

35. Glucose – 6 – phosphatase of liver is located at

a) cell membrane b) Mitochondrial inner membrane

c) cytosol d) membrane of endoplasmic reticulum

36. Which amino acid catalyse the initial attack reaction in glucogenin

a) Serine b) Threonine c) Tryptophan d) Tyrosine

37. The predominant hexokinase in liver in liver is

a) Hexokinase I b) Hexokinase II c) Hexokinase III d) Hexokinase IV

38. Which of the hexkinase have high Km value

a) Hexokinase I b) Hexokinase II c) Hexokinase III d) Hexokinase IV

39. Activity of hexokinase IV is inhibited by

a) glucose – 6 – phosphate b) glucose 1 – phosphate c) fructose – 6 phosphate d) All

40. Km of phosphofructose kinase I………………………….at high [ATP] ratio.

[ADP]

a) Increases b) Decreases d) Remain same

41. Inactivation of pyrucate kinase by phosphorylation in liver occurs when

a) Blood glucose level is high b) Glucoagon level in blood is high

c) Pyruvate level is high in cytosol d) All

42. Which of the following isn’t allosteric inhibitor of muscle pyruvate kinase?

a) Pyruvate b) Alanine c) ATP d) Acetyl coA

43. Fructose 2, 6 Bisphosphate lowers the Km value of which enzyme

a) phosphofructose kinase I b) Fructose 1, 6 bisphosphatase

c) Fructose 2, 6 bisphosphatase d) Phsphofructose kinase - 2

44. Fructose 2, 6 bisphosphate is formed when

a) Insulin level is high b) Glucose level in blood is low

c) Energy demand in liver cell is low d) TCA cycle intermediate don’t participate in biosynthesis reaction

45. Which of the following isn’t covalently attached with enzyme

a) FAD b) NAD⁺ c) lipoate d) Thiamin pyrophosphate

46. Which carbons of glucose are released as CO₂ when pyruvate is converted to Acetyl CoA.

a) 1 and 6 b)5 and 2 c) 4 and 3 d) 2 and 4

47. Avidin a protein in raw egg binds biotin and inhibits its absorption. Which enzyme activity may be inhibited when Avidin is intake?

a) pyruvate dehydroginase b) pyruvate carboxylase c) succinate dehydrogenase d) All

48. Pyruvate dehydrogenase complex is present in

a) cell membrane b) cytosol c) Mitochondria d) Endoplasmic reticulum

49. Lipoate is attached to with amino acid residue of Dihyropoyl transacetylase

a) His b) Lys c) phe d) Ser

50. No. of total electrons released when 1 molecule of glucose is converted to 2 molecule of Acetyl Coa

a) 2 b) 4 c) 8 d) 10

PHOTOSYNTHESIS REVIEW QUESTIONS FOR BIOLOGY

1. What is the primary function of photosynthesis?

2. (a) Name a gas released as by-product of the light dependent reactions of photosynthesis. (B) Name the molecule that is the source of this gas. (C) Why is oxygen removed from the molecule named in 2B?

3-4. Name two molecules that are produced during the light dependent reactions of photosynthesis and serve as temporary sites for energy storage.

5. When a molecule loses an electron, the molecule has been _?_ (oxidized or reduced or destroyed)

6. When a molecule gains an electron, the molecule has _?_ (gained energy or lost energy)

7. (A) True or False All electrons contain the same amount of energy. (B) If this statement were true, could life (at least as we know it) exist? Why?

8. When chlorophyll P680 absorbs sunlight, what subatomic particle actually has a change in energy content? (electron or proton or neutron)

9. When chlorophyll P680 loses an electron, from what atom does the chlorophyll receive an electron?

10. When chlorophyll P680 loses an electron, from what molecule does the chlorophyll receive an electron?

11. Which contains more energy: one molecule of NADP or one molecule of NADP-H ?

12. What is the name of the three carbon molecule that is a product of the Calvin cycle (= “dark” reactions)?

13. Name the molecule that is taken from the air and that provides the carbon for the production of carbohydrates during the Calvin cycle.

14. Which has the most energy: one photon of green light, one photon of red light, or one photon of blue light ?

15. Chlorophyll is green because it _?_ (absorbs, reflects, or transmits) green wave lengths of light.

16. In eukaryotic cells, photosynthesis occurs in organelles named _?_

17. How many molecules of carbon dioxide must enter the Calvin cycle in order for the plant to produce a sugar containing 24 carbon atoms?

18. The term phosphorylation means:

19. True or False The Calvin cycle (= light-independent reactions) can occur in a plant that is in dark room so long as the materials carbon dioxide, ATP, and NADP-H are present.

20. Which contains more energy: three molecules of carbon dioxide or one molecule of phosphoglyceraldehyde (= PGAL) ?

21. "Packets" or "particles" of light are called ?

22. What would happen to humans and most other living organisms on Planet Earth if photosynthesis stopped?

23. What is the range of wavelengths of light that are visible to humans?

24. What is the wavelength of UV light? infrared?

25. Which has more energy, short wave lengths of electro-magnetic radiation or long wave lengths of electro-magnetic radiation?

26. Summarize, in one sentence, what happens during the light dependent reactions of photosynthesis.

27. Summarize, in one sentence, what happens during the light independent reactions of photosynthesis.

28. What happens to an electron in an atom if the electron gains energy? loses energy?

29. What happens to an electron in chlorophyll in Photosystem II when the electron absorbs light energy?

30. High energy electrons in Photosystem I are used to manufacture molecules of ?

31. High energy electrons in Photosystem II are used to manufacture molecules of ?

ANSWERS

1. The primary function of photosynthesis is to capture light energy, convert some of this light energy into chemical energy, and store this chemical energy in molecules of carbohydrates (such as phosphoglyceraldehyde, glucose, or starch).

2. (A) Oxygen is released as a by-product (= “waste material”) of photosynthesis. (B) The oxygen atoms are removed from water as the water is broken down during the light reactions. (C) Water is broken down to provide hydrogen atoms (which, in turn, provide electrons to replace electrons that are lost from chlorophyll P680). At this point, oxygen is of no value to the system and, consequently, is released from the chloroplast and from the leaf into the surrounding air.

3-4. Two high-energy molecules that are produced during the light reactions are adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP-H). These two molecules temporarily store energy; they transfer energy into carbohydrates being produced during the light independent reactions (= Calvin cycle). The carbohydrates (PGAL, glucose, starch) can store energy for much longer periods of time.

5. When a molecule loses an electron, the molecule has been oxidized.

6. When a molecule gains an electron, the molecule has been reduced (and has gained energy that the electron brought.)

7. (A) False. Electrons vary tremendously in the amount of energy they contain. In this class, we typically do not use numbers or units to describe the energy levels of electrons. Instead, we simply refer to the electrons as being “low energy” or “high energy.” (B) If all electrons contained the same amount of energy (and could not gain or lose energy) life could not occur because living organisms must have energy available and this energy is captured and released primarily from electrons (in the reactions of photosynthesis and respiration.)

8. When chlorophyll P680 absorbs energy, an electron gains the energy. (Actually a series of electrons, one after the other, gains energy; however, if you understand what happens to one electron, then you understand what happens to each of the millions of other electrons in this series.)

9-10. When chlorophyll P680 loses an electron, the P680 molecule replaces this electron with an electron taken from an atom of hydrogen which has come out of a molecule of water. (Review: a hydrogen atom consists of one proton and one electron. If the electron is removed, only the proton remains. The proton will be used later, in Photosystem I, to join with an electron that is picked up by NADP. The result is the formation of NADP-H, one of products of the light-dependent reactions.)

11. A molecule of NADP-H contains more energy than a molecule of NADP. The NADP picks up a high-energy electron and combines the electron with a proton to form the hydrogen atom that is the “H” of the NADP-H. Compare NADP to an empty Wells Fargo armored delivery truck while NADP-H is the Wells Fargo truck loaded with money (or, in the case of NADP-H, loaded with energy).

12. The name of the 3-carbon product of the Calvin cycle is phosphoglyceraldehyde (which is also called glyceraldehyde phosphate) and is commonly symbolized as PGAL.

13. Carbon dioxide, in the form of a gas, is removed from the environment of a plant (either from the surrounding air or water, depending on whether the plant lives in air or submerged in water), taken into leaves and chloroplasts, and used as a carbon source during the manufacture of carbohydrates (such as PGAL, glucose, and starch) in the Calvin cycle.

14. The shortest wavelengths (such as violet) have more energy than do the longer wavelengths of light such as red. Of the three colors of light listed here (blue, green, red), blue has the shortest wavelength and, consequently, the most energy. If we compare the wavelengths longer than light (such as radio waves) with wavelengths shorter than light (such as X-rays), the differences in energy level are easier to appreciate. X-rays (short wavelengths with high energy levels) are dangerous to living cells because the X-rays can damage DNA in the chromosomes. Conversely, the long wavelengths of radio waves (with their low energy levels) are apparently harmless to cells.

15. Chlorophyll is green because it reflects green wavelengths of light and these are what we see.

16. Photosynthesis occurs in cell parts called chloroplasts that occur primarily in plant cells that are exposed to light. (Would the root cells of a plant be able to use chloroplasts?)

17. For each carbon atom that is released from the Calvin cycle in a high-energy carbohydrate molecule, one carbon dioxide molecule must enter the cycle. To produce one molecule of PGAL (which contains 3 carbon atoms), 3 molecules of carbon dioxide must enter the cycle; to produce one molecule of glucose (with 6 carbon atoms), 6 molecules of carbon dioxide must enter the cycle; to produce a molecule containing 24 carbon atoms, 24 molecules of carbon dioxide must enter the cycle.

18. The term phosphorylation refers to the addition of a phosphate group to an atom or molecule. The addition of the phosphate involves the addition of large amounts of energy. This energy may come from light (as in the light reactions of photosynthesis) or from the breakdown of sugars (as in cellular respiration).

19. True. The Calvin cycle requires the input of carbon dioxide (as a source of carbon for building carbohydrates) and the availability of ATP and NADP-H to provide energy to reduce the carbon dioxides and construct high-energy carbohydrates. If these materials (carbon dioxide, ATP, and NADP-H) are available, the Calvin cycle can occur, even in darkness. Normally, however, what would happen to the quantities of ATP and NADP-H shortly after the plant is placed in darkness? (The light dependent reactions would shut down and no more ATP and NADP-H would be produced. When the available supplies of ATP and NADP-H are used up, the Calvin cycle would stop.)

20. One molecule of phosphoglyceraldehyde (= PGAL) contains more energy than three molecules of carbon dioxide. During the Calvin cycle (the light independent reactions) the low energy carbon atoms in carbon dioxide are reduced (i.e., they gain energy from ATP and NADP-H).

21. Packets or “bundles” of light energy are called photons.

22. If photosynthesis stopped, most living organisms on Planet Earth, including humans, would die due either (A) to a shortage of energy because no food molecules would be available or (B) to a shortage of oxygen for cellular respiration.

23. The wavelengths of light that are visible to humans range from approximately 400 nanometers (violet) to 700 nanometers (red). Some animals can see additional wavelengths. For example, some insects can see ultraviolet light.

24. Ultraviolet light (= UV light) has a shorter wavelength than violet (which has a wavelength of about 400 nanometers; infrared has a longer wavelength than red (which has a wavelength of about 700 nanometers).

25. The shorter wavelengths have more energy; therefore, UV light has more energy per photon than does infrared. One consequence of this is that the shorter wavelengths are more likely to be dangerous to living cells.

26. Light energy is absorbed by electrons that supply energy for the formation of molecules of ATP and NADP-H which are used as temporary energy storing molecules.

27. Molecules of carbon dioxide enter the Calvin cycle where the carbons are reduced by acquiring energy from ATP and NADP-H (from the light dependent reactions) and high energy molecules of PGAL are constructed.

28. If an electron gains energy it moves to an outer shell; if the electron gains enough energy, the electron may be driven out of the atom.

If an electron loses energy it moves to an inner shell (i.e., closer to the nucleus of the atom).

29. The electron gains so much energy (by absorbing photons) that the electron leaves the chlorophyll molecule. The electron is now described as a “high-energy electron” and can provide energy for the formation of molecules of ATP.

30. High energy electrons in Photosystem I are used to manufacture molecules of NADP-H.

31. High energy electrons in Photosystem II are used to manufacture molecules of ATP.

Photosynthesis

1. Excitation of P700

a) greatly reduces its reduction potential c)greatly increases its reduction potential

b) has no effect on the reduction potential d)has effects on oxidation potential only.

2. The energy required to excite PSI is

a) less than that needed to excite PSII c) more than that needed to excite PSII

b) equal to that needed to excite PSII d) it can’t be told

3. Cytochrome b₆f complex is present:

a) in the grand lamellae c) in the stromal lamellae

b) throughout the thyllakoid membrane d) exclusively in stroma

4. Which of the following is not “one electron carrier”?

a) Cytochrome b) Fe-S protein c) Quinone d) None

5. During light reaction, the direction of proton flow is from

a) Stroma to thyllakoid membrane c)Thyllakoid membrane to stroma

b) Stroma to out of chloroplast d) Lamellae to lumen

6. During cyclic electron flow which of the following is produced?

a) ATP b) NADH c) NADPH d)O_{2 e)} all

7. No. of photons required to evolve O2 during oxygenic photosynthesis is

a) 4 b) 6 c) 8 d) 10

8. Which of the following is a soluble-Cu containing electron transfer protein?

a) Cytochrome b) Pheophytin c) Plastoquinone d) Plastocyanin

9. Plastocyanin is present on which side?

a) Stroma b) Lumen c) Lamellae d) All

10. During the electron flow from Cytochrome b₆f to plastocyanine which side has maximum protons?

a) Stroma b) Lumen c) Lamellae d) Grana

11. Cytochrome c₆ in Cyanobacteria is homologous to

a) Mitochondrial cytochrome c b) Plastocyanin as in plants

c) Mitochondrial cytochrome bc₁ d) a & b e) a,b & c

12. How does ATP synthesized in chloroplasts get into the cytosol?
A. It is transported as sucrose.
B. It is transported directly by a membrane transporter.
C. It is transported as triose phosphate.
D. It is transported as inorganic phosphate (P_i).

13. The net outcome of light reaction in green plant is:

a)3ATP & 3NADPH b)2NADPH & 2ATP c)3ATP & 2NADPH d)2ATP & 3 NADPH

14. The large and small subunits of Rubisco are encoded respectively in the

a) Chloroplast and nuclear genome b) nuclear and chlorophyll genome

c) both in nuclear genome d) Bone in chlorophyll genome

15. Chlorophyll contains all glycolytic enzymes except

a) Phosphoglycerate mutase b) Phosphoglycerate isomerase c) Triose –P- mutase d) Triose – P – isomerase

16. Glycine decarboxylase is present at very high levels in mitochondria of:-

a) C₄ plants b) CAM plants c) C₃ plants d) None

17. 11. Which of the following reactions is catalyzed by transketolase?
A. glyceraldehyde 3-phosphate + dihydroxyacetone phosphate fructose 1,6-bisphosphate
B. ribose 5-phosphate ribulose 5-phosphate
C. ribulose 5-phosphate ribulose 1,5-bisphosphate
D. fructose 6-phosphate + glyceraldehyde 3-phosphate erythrose 4-phosphate + xylulose 5-phosphate

18. CO₂ fixed by mesophyll cells gets transported to neighboring bundle-sheath cells by
A. the movement of oxaloacetate that diffuses between the neighboring cell membranes.
B. the movement of oxaloacetate that passes through channels that connect the cells.
C. the movement of malate that passes through channels that connect the cells.
D. the movement of pyruvate that passes through channels that connect the cells.

19. “Nocturnal inhibitor” 2-carboxyarabinitol1-phosphate is a structural analog of

a) Ribulose 1,5-bisphosphate b) Enediolate intermediate

c) Beta ketoacid intermediate d) Hydrated intermediate.

20. Central to the rubisco activity is the carbamoylated ____ residue

a) Lys201 b) lys 175 c) His 294 d) Leu 101.

21. Which of the following represents the sequence of electron flow in the light reactions of photosynthesis in higher plants?

(A) H2O → photosystem I → photosystem II → NADP

(B) H2O → photosystem II → photosystem I → NADP

(C) H2O → photosystem II → photosystem I → ATP

(D) NADPH → photosystem I → photosystem II → O2

(E) Photosystem I → photosystem II → NADPH → O₂

Enzyme kinetics

A catalyst alters the rate of a chemical reaction by:

A) always providing a surface on which molecules react

B) changing the products formed in the reaction

C) inducing an alternate pathway for the reaction with generallylower activation energy

D) changing the frequency of collisions between molecules

ANSWER: C

Choose the INCORRECT answer. The rate of a chemical reaction:

A) usually is increased when the concentration of one of the reactants is increased

B) is dependent on temperature

C) may be inhibited sometimes by certain catalytic agents

D) will be very rapid if the activation energy is large

ANSWER: D

If a reaction is first order with a rate constant of 5.48 x 10^-2 sec^-1, how long is required for 3/4 of the initial concentration of reactant to be used up?

A) 25.3 sec

B) 36.5 sec

C) 6.3 sec

D) 18.2 sec

E) none of these

ANSWER: A

The rate constant at 160 ^oC for the first order decomposition of ore is 0.032/min. The half-life of the reaction is:

A) 62.5 sec

B) 31.25 sec

C) 5000 sec

D) 111 sec

E) none of these

ANSWER: E

A reaction is first order. If its initial rate is 0.0200 M/sec and 25.0 days later its reaction is 6.25 x 10^-4 m/sec, then its half-life is:

A) 12.5 days

B) 5.0 days

C) 25.0 days

D) 50.0 days

E) none of these

ANSWER: B

For 2NO + O₂ --> 2NO₂ , initial rate data are:

[NO]	0.010	0.010	0.030 M
[O2 ]	0.010	0.020	0.020 M
rate	2.5	5.0	45.0 mM/sec

The rate law is Rate = k[O₂ ]^y and

A) x = 1 y = 2

B) x = 2 y = 1

C) x = 1 y = 1

D) x = 2 y = 2

E) none of these

ANSWER: B

A and B are mixed and the reaction is timed until a color change occurs. The data are:

[A]	0.100	0.050	0.100M
[B]	0.140	0.140	0.070M
time	25 sec	50 sec	100 sec

The order of the reaction in terms of [A] is:

A) second

B) half

C) zero

D) first

E) none of these

ANSWER: D

For the reaction 2HgCl₂ + C₂O₄^2- --> products, data are:

[HgCl2 ], M	0.0836	0.0836	0.0418
[C2O42- ] ,M	0.202	0.404	0.404
Init. rate, M/hr	0.26	1.04	0.53

The rate law is Rate = [HgCl ] ^x [C₂O₄^2-] ^y . Thus

A) x = 2 y = 1

B) x = 2 y = 2

C) x = 1 y = 2

D) x = 1 y = 1

E) none of these

ANSWER: C

The correct units of the specific rate constant for a zero order reaction are:

A) L/mol-sec

B) sec^-1

C) sec

D) L² /mol^{2 .}sec

E) none of these

ANSWER: E

If the half-life of a reaction depends on the concentration of the reactant, then the reaction cannot be __________ order.

A) second

B) zero

C) first

D) third

E) none of these

ANSWER: C

The reaction has the rate law Rate = k[A][B]². Which will cause the rate to increase the most?

A) doubling [A]

B) lowering temperature

C) tripling [B]

D) quadrupling [A]

E) doubling [B]

ANSWER: C

The reaction 2 H₂ + NO ---> H₂O + 1/2 N₂ is first order in H₂ and second order in NO. The rate law is:

A) k[H₂]² [NO]

B) k[H₂][NO]²

C) k[H₂]

D) k[H₂][NO]

E) none of these

ANSWER: B

For a reaction Rate = k[A][B]², what factor will NOT change k?

A) raising temperature

B) adding inhibitor

C) increasing [A]

D) adding catalyst

E) none of these

ANSWER: C

A variable that has NO EFFECT on reaction rate is:

A) energy of activation

B) temperature

C) catalyst

D) concentration

E) none of these

ANSWER: E

What is the main difference between a Pt catalyst and an enzyme catalyst?

ANSWER: enzyme has greater substrate specificity

What is the order of reaction for the following reaction. Rate = k[A]^-1/2[B]^1/2 ?

ANSWER: zero order overall

Substance A decomposes by a first-order reaction. Starting initially with [A] = 2.00 M, after 150 min [A] = 0.50 M. For this reaction what is t_1/2 ?

ANSWER: 75.0 min

For the above reaction, what is k?

ANSWER: 9.24 x 10^-3 min^-1

-------------------------------------

In the first order reaction A ---> products, [A] = 0.400 M initially and 0.250 M after 15.0 min.

What is the value of the rate constant, k?

ANSWER: 0.034 min^-1

What is the half-life of the reaction?

ANSWER: 20.4 min

At what time will [A] = 0.200 M?

ANSWER: 20.4 min

What will [A] be after 175 min.?

ANSWER: 1.04 x 10^-3 M

-------------------

The reaction A + B --> C + D is second order in A and zero order in B. The value of k is 0.012 M^-1 min^-1 . What is the rate of this reaction when [A] = 0.125 M and [B] = 0.435 M?

ANSWER: 1.88 x 10^-4 M min^-1

Which of the following statements is true about the reaction 2A --->B + C which is first order in A and first order overall:

A) The rate of the reaction will decrease at higher concentrations of B and C.

B) The time required for one half of A to react is directly proportional to the quantity of A.

C) The rate of formation of C is twice the rate of reaction of A.

D) The rate of formation of B is the same as the rate of reaction of A.

E) none of these

ANSWER: E

A catalyst

A) takes part in a reaction and speeds it up

B) appears in the rate equation of a chemical reaction

C) provides an alternate reaction pathway

D) raises the activation energy of a reaction

E) none of the above

ANSWER: C

Define heterogeneous catalysis.

ANSWER: The catalyst is present in a different phase of matter than are the reactants and products.

The rate of a specific chemical reaction is independent of the

concentrations of the reactants. Thus the reaction is

A) first order

B) second order

C) exothermic

D) catalyzed

E) none of these

ANSWER: E

Which of the following does not determine the rate of a reaction?

A) value of DELTA H⁰

B) activation energy

C) presence of a catalyst

D) temperature of reactants

E) none of these

ANSWER: A

Which of the following lowers the activation energy of a reaction?

A) adding reactants

B) lowering the temperature

C) removing products

D) adding a catalyst

E) raising the temperature

ANSWER: D

If a reaction has a rate equation of rate = k[A][B][C] then it is

A) second order

B) first order

C) third order

D) zero order

E) cannot be determined

ANSWER: C

The first-order reaction A --> Products has a half-life, t_1/2, of 55.0 min at 25 ^oC and 6.8 min at 100 ^oC. What is the activation energy for this reaction?

ANSWER: 25.8 kJ/mol

Which of the following statements is CORRECT

A) A zero order reaction depends on the concentration ofreactants.

B) A reaction rate cannot be calculated from the collision frequency alone.

C) A commonly stated rule of thumb is that reaction rates triple for a temperature increase of about 10 ^oC.

D) none of these

ANSWER: B

The first order reaction A---> products has t_1/2 = 150 sec. What percent of the sample remains unreacted after 300 sec?

ANSWER: 25%

Define rate law.

ANSWER: An experimentally determined equation that describes how the rate of reaction depends on the concentration of reactants

Define activation energy.

ANSWER: The minimum total kinetic energy that molecules must bring to their collisions for a chemical reaction to occur.

The rate constant for a first-order reaction is k = 0.00073 s^-1.

Determine the percent of reactant that has decomposed after 500 s.

ANSWER: 30.6%

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For the reaction A---> products, the following data are obtained:

First Experiment		Second Experiment
[A] = 1.512 M	t = 0 min	[A] = 3.024 M	t = 0 min
[A] = 1.490 M	t = 1.0 min	[A] = 2.935 M	t = 1.0 min
[A] = 1.469 M	t = 2.0 min	[A] = 2.852 M	t = 2.0 min

Determine the order of the above reaction.

ANSWER: second order

What is the rate constant, k?

ANSWER: 9.62 x 10^-3 mol^-1 min^-1

What is the concentration of [A] in the first experiment after 4.0 min?

ANSWER: 1.429 M

What is the initial rate of the reaction in each experiment?

ANSWER: First experiment = 0.022 mol/min Second experiment = 0.089 mol/min

sources: http://itl.chem.ufl.edu/2041_f97/kinetics_quiz.html

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more question for bioenergetics and oxidative phosphorylation

1. Which one of the following statements is most correct?
A Oxidation of pyruvate to carbon dioxide and water does not involve the TCA cycle.
B The major pathway for electron transfer to oxygen in the electron transport system does not involve pyridine nucleotides.
C An adequate supply of ADP is required for maximal respiration by mitochondria.
D Coenzyme Q is a prosthetic group of a flavoprotein.
E Substrate level phosphorylation cannot occur in the absence of oxygen

2.	Which one of the following enzyme systems may be used as a marker enzyme for mitochondrial electron transport system?
A	Glucose 6-phosphate dehydrogenase
B	Succinate dehydrogenase (succinate-cytochrome c reductase)
C	Phosphoenolpyruvate carboxykinase
D	Lactate dehydrogenase
E	Acetyl-CoA carboxylase 3. Rotenone inhibits malate oxidation but not succinate oxidation because A it is a competitive inhibitor of malate dehydrogenase. B it does not react with flavoprotein enzymes. C it inhibits at the NADH dehydrogenase while succinate dehydrogenase interacts with the respiratory chain at ubiquinone, bypassing this site of inhibition. D it inhibits at cytochrome b while succinate dehydrogenase interacts with the respiratory chain at cytochrome c. E it inhibits at the cytochrome oxidase but succinate is oxidized by a flavin oxidase. 4. Cyanide is a deadly poison because it A binds to myoglobin. B interferes with respiratory control. C forms addition compounds with important aldehydes such as pyridoxal. D reacts with cytochrome oxidase. E inhibits the cytochrome P-450 monooxygenases. 5. The main function of the mitochondrial electron transport chain is to A generate a P/O ratio of 2.5. B recycle NAD for glycolysis. C provide reducing equivalents. D lower the oxidation state of the cell. E generate energy for ATP formation. 7. Which of the following tissues has the lowest respiratory rate? A adipose tissue B brain C liver D red blood cell E skeletal muscle sources: https://med-eval.med.uiuc.edu/cgi-bin/exam/practicefeedback.p

question for oxidative phosphorylation

1. Which of the following is true about the difference between oxidative phosphorylation and photophosphorylation?
A. Photophosphorylation occurs only in photosynthetic organisms and oxidative phosphorylation occurs only in non-photosynthetic organisms.
B. In oxidative phosphorylation, NADH donates electrons; in photophosphorylation NADPH donates electrons.
C. Photophosphorylation occurs only in light; oxidative phosphorylation occurs only in darkness.
D. In oxidative phosphorylation, O2 is reduced to H2O; in photophosphorylation, H2O is oxidized to O2.


2. Which of the following processes takes place in the mitochondrial matrix?
A. cellular respiration
B. glycolysis
C. fatty acid oxidation
D. photosynthesis


3. Which of the following is true about the expression of mitochondrial genes?
A. Mitochondria encode all of the proteins needed to make new mitochondria.
B. Mitochondria can translate their own genes.
C. Mitochondria import all of their proteins from the cytoplasm.
D. Mitochondrially-encoded genes are expressed in the cytoplasm.


4. Diseases caused by mutations in mitochondrial genes are invariably inherited from the mother because
A. mitochondrial genes are encoded on the X chromosome.
B. males do not have mitochondrial DNA.
C. all of the mitochondria of a developing embryo are derived from the mother's egg.
D. mitochondrial genes of males are turned off.


5. How do mitochondria eliminate the harmful superoxide free radical ·O2- that is generated with low frequency during oxidative phosphorylation?
A. Glutathione reductase reduces ·O2- to H2O.
B. Superoxide dismutase converts ·O2- to H2O2.
C. Glutathione peroxidase converts ·O2- to O2.
D. ·O2- is transported out of mitochondria.


6. Which of the following processes yields the greatest number of ATP molecules when a molecule of glucose is completely oxidized?
A. lactate fermentation
B. pyruvate oxidation
C. glycolysis
D. the citric acid cycle


7. How does thermogenin keep newborn mammals warm?
A. It makes oxidative phosphorylation more efficient.
B. It causes the transfer of electrons from ubiquinone directly to oxygen.
C. It uncouples electron transport from ATP synthesis.
D. It stimulates the accumulation of brown fat.


8. The light-dependent and carbon-assimilation reactions of photosynthesis are linked in that
A. the light-dependent reactions generate the chemical energy needed for carbon-assimilation.
B. the oxidation of carbohydrates from the carbon-assimilation reactions drives the synthesis of ATP in the light-dependent reactions.
C. carbon dioxide generated in the light-driven reactions is converted to triose phosphates in the carbon-assimilation reactions.
D. NADPH generated in the carbon-assimilation reactions drives the synthesis of ATP in the light-dependent reactions.


9. In which part of the chloroplast do the light-dependent reactions of photosynthesis take place?
A. in the thylakoid lumen
B. in the thylakoid membrane
C. in the stroma
D. in the inner membrane


10. What is the role of antenna molecules in photosynthesis?
A. to donate their electrons for use in oxidation-reduction reactions
B. to release absorbed energy as fluorescence
C. to transmit light energy to reaction centers
D. to transduce light energy into chemical energy


11. The F0 complex of mitochondrial ATP synthase
A. is inhibited by oligomycin.
B. synthesizes ATP.
C. pumps protons into the mitochondrial matrix.
D. is a peripheral membrane protein.


12. Which complex of the respiratory chain is inhibited by cyanide?
A. Complex IV
B. ATP synthase
C. Complex I
D. Complex III


13. How will oxidative phosphorylation be affected by placing intact mitochondria in a weak acid that can readily diffuse across the mitochondrial membranes?
A. Electron transfer reactions will be inhibited.
B. No H2O will be generated.
C. ATP will be able to be synthesized in the absence of an oxidizable substrate.
D. ATP synthesis will be inhibited.


14. Complexes I and II of the mitochondrial respiratory chain
A. have heme prosthetic groups.
B. transfer electrons directly to ubiquinone.
C. pump protons from the matrix to the intermembrane space.
D. transfer electrons from NADH.


15. How does NADH generated by glycolysis in the cytosol get conveyed into mitochondria for oxidation in the respiratory chain?
A. It diffuses through the inner mitochondrial membrane.
B. Its reducing equivalents are transported across the inner mitochondrial membrane.
C. It is transported across the inner mitochondrial membrane as aspartate.
D. It is transported directly across the inner mitochondrial membrane by an NADH transporter.


sources: http://bcs.whfreeman.com/lehninger/pages/bcs-main.asp?v=chapter&i=19070.01&s=19000&n=00070&o=|00510|00520|0

Lehninger Principles of Biochemistry

questions for amino acids and nucleotide biosynthesis

1. Which chemical reaction depicts nitrification?
A. N₂ ® NH₄⁺
B. NO₃^- ® NH₄⁺
C. NO₂^-® NO₃^-
D. NO₃^- ® N₂

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2. Glutamine is derived from which glycolysis or citric acid cycle intermediate?
A. pyruvate
B. a-ketoglutarate
C. oxaloacetate
D. 3-phosphoglycerate

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3. Newborn infants sometimes develop jaundice because of an accumulation of
A. heme.
B. biliverdin.
C. urobilin.
D. bilirubin.

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4. In the de novo pathway, what is the immediate precursor to dTMP?
A. dUMP
B. TMP
C. thymidine
D. dCMP

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5. Which of the following is true about the de novo synthesis of nucleotides?
A. Deoxyribonucleotides are precursors of ribonucleotides.
B. Pyrimidines are precursors of purines.
C. Bases are synthesized then attached to ribose or deoxyribose.
D. Amino acids are precursors of nucleotides.

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6. Plants carry out
A. reduction of nitrate.
B. denitrification.
C. nitrification.
D. nitrogen fixation.

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7. Which of the following molecules is not derived from glycine?
A. glutathione (GSH)
B. heme
C. serotonin
D. phosphocreatine

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8. The conversion of serine to glycine requires which of the following?
A. S-adenosylmethionine (adoMet)
B. 5-phosphoribosyl-1-pyrophosphate (PRPP)
C. NADH
D. tetrahydrofolate (H₄ folate)

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9. Nucleoside diphosphate kinase catalyzes which reaction?
A. ATP + AMP 2 ADP
B. ATP + dCDP ADP + dCTP
C. ATP + dGMP ADP + dGDP
D. ATP + UMP ADP + UDP

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10. Adenosine deaminase deficiency leads to
A. gout.
B. Lesch-Nyhan syndrome.
C. severe immunodeficiency disease.
D. porphyria.

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11. Which of the following molecules does not result from decarboxylation of an amino acid?
A. histamine
B. spermidine
C. g-aminobutyrate (GABA)
D. dopa

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12. Which of the following is true about the symbiotic relationship between leguminous plants and nitrogen-fixing bacteria?
A. Leguminous plants produce leghemoglobin to prevent oxygen from interfering with the bacterial electron-transfer system.
B. Nitrogen-fixing bacteria obtain citric acid intermediates from the leguminous plants.
C. Nitrogen-fixing bacteria are present on the leaves of the leguminous plants.
D. Leguminous plants produce the nitrogenase complex used by the bacteria to fix nitrogen.

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13. Chorismate is an intermediate in the synthesis of which amino acid?
A. phenylalanine
B. proline
C. serine
D. cysteine

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14. In the salvage pathway, how are nucleotides generated?
A. Free bases are attached to ribose, which is then phosphorylated to generate the corresponding NMPs.
B. Free bases exchange with the bases on NMPs.
C. Free bases react with 5-phosphoribosyl-1-pyrophosphate (PRPP) to generate the corresponding NMPs.
D. Purine and pyrimidine bases are built up while attached to ribose throughout the process.

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15. Parkinson's disease is associated with
A. an underproduction of dopamine.
B. an underproduction of g-aminobutyrate (GABA).
C. an overproduction of histamine.
D. an overproduction of dopamine.

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16. AMP is converted to adenosine by what enzyme?
A. nucleotidase
B. 5'-nucleotidase
C. adenosine deaminase
D. ribonucleotide reductase

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17. Which of the following occurs in the degradation pathway of AMP?
A. Adenine is converted to hypoxanthine.
B. The end product is urea.
C. AMP is converted to adenosine.
D. Adenosine is converted to adenine.

sources: http://bcs.whfreeman.com/lehninger/pages/bcs-main.asp?v=chapter&s=22000&n=00070&i=22070.01&o=|00510|00520|00530|00540|00550|00PRS