bio practice questions for exam 3

1. Energy is neither created nor destroyed: This is the ______st law of thermodynamics.

1st

2. The enzyme binds to the substrate at its ________ site.

active

3. An enzyme can be denatured if its optimal ______ and optimal ______ are not maintained.

temperature, pH

An enzyme speeds up the rate of a reactions by decreasing the amount of _______ energy required for that reaction to take place.

activation energy, Ea

A competitive inhibitor binds to the _______________ of the enzyme and prevents the ________ from binding.

active site, substrate

6. A non competitive inhibitor binds to a ______ _______ of the enzyme.

separate site (anywhere other than the active site)

7. A reaction in which energy is released is ____________gonic

exergonic

8. After a chemical reaction the enzyme shape remains ____________.

the same

9. Starch is broken down into glucose. This is an example of _____________lism

catabolism

10. A protein is made using amino acids. This an example of ____________lism

anabolism

11. Usually, a chemical reaction is designated as exergonic rather than endergonic when:
a. activation energy is required
b. the products are less complex than the reactants
c. activation energy exceeds net energy release
d. it absorbs more energy

B - since the reaction is releasing energy

12. The first law of thermodynamics :
a. deals with entropy
b. states that energy is neither created nor destroyed
c. deals with heat content
d. states that entropy spontaneously increases
e. predicts the direction of a reaction

B

13. If enzyme is saturated with substrate, what happens?

Reaction rate increases since there is more substrate to react with the enzyme

14. Why do enzymes act on specific substrates?

Enzymes have active sites that will only accept substrates its shaped for

A(n) _____ reaction occurs spontaneously.
Anabolic;
endergonic;
chemical;
exergonic;
kinetic

Exergonic

Which of these reactions requires a net input of energy from its surroundings?
Exergonic;
endergonic;
ATP --> ADP + P;
catabolic

Endergonic - since they are reactions that require energy

The reaction ADP + P --> ATP is a(n) _____ reaction.
exergonic ;
endergonic;
non spontaneous;
catabolic

Endergonic

The energy for an endergonic reaction comes from a(n) _____ reaction.

a. exergonic
b. synthesis
c. spontaneous
d. anabolic

Exergonic

What is energy coupling?
A. a description of the energetic relationship between the reactants and products in an exergonic reaction
B. the use of an enzyme to reduce EA
C. a barrier to the initiation of a reaction
D. the use of energy released from an exergonic reaction to drive an endergonic reaction

D

What is a catalyst? An enzyme is a ____________ catalyst

Protein/Biological

What is activation energy?

The amount of energy needed to start a chemical reaction

Nearly all enzymes are _____
a. carbohydrates;
b. minerals;
c. lipids;
d. nucleic acids;
e. proteins

Proteins

Enzymes work by _____.
a. adding a phosphate group to a reactant
b. decreasing the potential energy difference between reactant and product
c. adding energy to a reaction
d. reducing Activation energy (EA)

D

State whether the following enzyme facts are true or false. An enzyme:
A. is a source of energy for endergonic reactions:
B. increases the EA of a reaction:
C. is a inorganic catalyst:
D. can bind to nearly any molecule :
E. remains unchanged at the end of a reaction:
F. binds to the substrate at its active site.
G. Is not affected by environmental or chemical factors : pH, temp, salt
H. Is used up in a reaction:

A: False
B: False
C: False
D: False
E: True
F: True
G: False
H: False

The reactants in cellular respiration are ______________________________ and the products are _______________________________.

Glucose and Oxygen, ATP, Co2 and H20

How many ATP is the cell producing per glucose molecule during
a. aerobic respiration? ____
b. anaerobic respiration?___________

38 - the whole cellular respiration cycle
2 - processes like glycolysis, the citric acid cycle because they use no oxygen

Stage of respiration in which ATP is produced from NADH and FADH2: _________

Oxidative phosphorylation

How many ATPS generated per NADH molecule? ___________ per FADHs molecule? ______

2-3, 2-3

Write the location in the eykaryotic cell (specific location in the organelle)where these stages of respiration take place.
a. Glycolysis: ________________
b. Transition reaction: _____________
c. Krebs cycle: ____________
d. Electron transport chain:______________

A: in the cytosol of the cell
B: mitochondrial matrix
C: mitochondrial matrix
D: inner mitochondrial membrane

Where in the cell does fermentation take place? _____

in the cytosol of BOTH prokaryotic and eukaryotic cells

(fermentation is basically just the single process of glycolysis)

Will Kreb's cycle take place in the absence of oxygen? ___________

yes, it is an anaerobic and does not require oxygen to function

If oxygen is depleted, what alternate path would the respiration process take?

fermentation

Why is oxygen called the final electron acceptor?

because of its very high electronegativity and its presence at the end of the electron transport chain

*once electrons pass through the electron transport chain, they have lower energy and oxygen can pick them up easily

The transition reaction involves conversion of pyruvate to ____________

Acetyl CoA (oxidized)

CO2 is produced during the ________________ reaction and the ____________cycle

transition reaction/pyruvate oxidization, citric acid cycle

The invaginations (infoldings) of the inner mitochondrial membrane are called the _______.

cristae

In the absence of oxygen, muscle cells convert pyruvate to ______________

lactate

. In the reaction C6H12O6 + O2 + H2O CO2 + H2O + ATP + Heat
a. The reactant molecule that has a loss of electrons is __________
b. The reactant molecule that gets reduced is____ ____

C6H12O6, O2

. A molecule becomes more oxidized when it _____.
a. changes shape
b. gains a n electron
c. loses a n electron gains a water molecule

C

In the overall process of glycolysis and cellular respiration, ___ is oxidized and ___ is reduced.
a. oxygen; ATP
b. ATP; oxygen
c. glucose; oxygen
d. carbon dioxide; water
e. glucose; ATP

C, because glucose being oxidized is literally all glycolysis is, and oxygen is reduced at the end of the electron transport chain where it gains the electrons and becomes water

Most of the ATP produced in cellular respiration comes from which of the following processes?
a. Glycolysis
b. oxidative phosphorylation
c. reduction of NADH
d. substrate-level phosphorylation
e. the citric acid cycle

B

If the cell makes 4 NADH and 3 FADH2 molecules, the amount of energy available is used to make _______________ ATP (number).
a. 7
b. 18
c. 17
d. hard to determine that

D, because the number of ATP produced can vary from 2-3

The function of cellular respiration is to _____.
a. reduce CO2
b. extract CO2 from the atmosphere
c. extract usable energy from glucose
d. synthesize macromolecules from monomers
e. produce carbohydrates

C

Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 38 ATP from one glucose molecule. What happens to the rest of the energy in glucose?
a. It is stored as fat.
b. It is converted to heat.
c. It is used to make water from hydrogen ions and oxygen.
d. It is released as carbon dioxide and water
e. It is converted to starch.

B, 2nd law of thermodynamics because the energy is being converted so entropy increases

A small amount of ATP is made in glycolysis by which of the following processes?
a. transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
b. harnessing energy from the sun
c. transport of electrons through a series of carriers
d. transfer of electrons and hydrogen atoms to NAD+

A

During respiration in a eukaryotic cell, reactions of glycolysis occur _____.
a. in the cytosol
b. in the matrix of the mitochondrion
c. in the inner membrane of the mitochondrion
d. in the intermembrane space of the mitochondrion

A

What is the name of the process in which glucose is converted to pyruvate with the production of ATP and NADH?
a. Chemiosmosis
b. fermentation
c. glycolysis
d. citric acid cycle

C

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following?
a. oxidative phosphorylation
b. substrate-level phosphorylation
c. glycolysis
d. anabolic pathways
e. the citric acid cycle

E

In preparing pyruvate to enter the citric acid cycle, which of the following steps does occur?
a. A carbon atom is released in carbon dioxide.
b. A compound called coenzyme A binds to a two-carbon fragment. c. It is oxidized, and the resulting electrons reduce an NAD+ to an NADH.
d. None of the above are steps in the metabolism of pyruvate before its entry into the citric acid cycle.
e. The three steps above are all involved in the metabolism of pyruvate before its entry into the citric acid cycle.

E

In the citric acid cycle, for each pyruvate that enters the cycle, 1 ATP, 3 NADH, and 1 FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle?
a. 2 ATP, 6 NADH, 2 FADH2
b. 4 ATP, 6 NADH, 2 FADH2
c. 3 ATP, 3 NADH, 1 FADH2
d. 1 ATP, 3 NADH, 1 FADH2

A, the citric acid cycle runs twice, doubling everything

During respiration in eukaryotic cells, reactions of the citric acid cycle occur _____.
a. in the cytosol
b. in the matrix of the mitochondrion
c. in the cristae of the mitochondrion
d. in the intermembrane space of the mitochondrion
e. across the inner membrane of the mitochondrion

B

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?
a. at the end of the citric acid cycle to regenerate citric acid
b. between glycolysis and the citric acid cycle to split a carbon from pyruvate, producing CO2
c. as a source of O2 in every reaction that produces CO2
d. at the end of the electron transport chain to accept electrons and form H2O

D

Which one of the following best describes the electron transport chain?
a. Electrons are pumped across a membrane by active transport.
b. Acetyl CoA is fully oxidized to CO2.
c. Hydrogen atoms are added to CO2 to make an energy-rich compound.
d. Electrons are passed from one carrier to another, releasing a little energy at each step.
e. Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle

D

Which one of the following is the source of the energy that produces the chemiosmotic gradient
in mitochondria?
a. ATP
b. an ATP-dependent proton pump
c. the production of NADH
d. the components of the electron transport chain
e. electrons moving down the electron transport chain

E

During respiration in eukaryotic cells, the electron transport chain is located in or on the _____.
a. cytosol
b. matrix of the mitochondrion
c. inner membrane of the mitochondrion
d. intermembrane space of the mitochondrion
e. none of the above

C

The overall efficiency of respiration (the percentage of the energy released that is saved in ATP) is approximately _____.
a. 0.5%
b. 2%
c. 40%
d. 100%

C

Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds?
a. ATP
b. lactate
c. carbon dioxide
d. ADP

B, since lactate is formed from fermentation which is an anaerobic process

In brewing beer, maltose (a disaccharide of glucose) is _____.
a. a flavoring ingredient
b. the substrate for aerobic respiration
c. the substrate for alcoholic fermentation
d. one of the enzymes for alcoholic fermentation
e. a substitute for pyruvate that cannot be made in yeast

C

If muscle cells in the human body consume O2 faster than it can be supplied, which of the
following is likely to result?
a. The muscle cells will have more trouble making enough ATP to meet their energy
requirements.
b. The cells will not be able to carry out oxidative phosphorylation.
c. The cells will consume glucose at an increased rate.
d. Only the first two answers are correct.
e. The first three answers are correct.

E

How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?
a. 2
b. 4
c. 3
d. about 38 ATP

B

Which of the following accompanies the conversion of pyruvate to acetyl CoA in the transition reaction?
a. formation of CO2 and ATP
b. formation of CO2 and NADH
c. formation of CO2 and coenzyme A
d. regeneration of NAD+

B

The energy given up by electrons as they move through the electron transport chain is used in which of the following processes?
a. the breakdown of glucose
b. the oxidation of water
c. pumping H+ across a membrane
d. the production of NADH and FADH2

C

41. The reactants in photosynthesis are _______________ and ____________.

sunlight, carbon dioxide and water

glucose and oxygen

42. Non Cyclic electron flow in photosynthesis produces _______________

ATP, NAPDH, Oxygen

43. The product of cyclic flow in photosynthesis is _____________________

G3P (glucose)

44. In green plants, the primary function of the Calvin cycle is to: ______________

create 3 carbon sugars (G3P) 1 to be used outside of the cell and make glucose and 5 to regenerate RuBP to continue the Calvin cycle

In a plant cell, where do the following take place (give specific location in the organelle)
a. Calvin cycle:_________________
b. Light reaction:_____________

A: in the stroma (cytosol) of chloroplasts
B: in the thylakoid membrane (innermost membrane)

46. The waste product of photosynthesis is ___________

oxygen

What is the role of the following in respiration / photosynthesis? Choose from the following
Electron carrier, CO2 acceptor; final electron acceptor; source of electrons
i. NADH:
ii. Rubisco:
iii. Oxygen in respiration:
iv. Water in photosynthesis:

1) NADH is found in the cellular respiration process where it's used to carry electrons to the electron transport chain
2) Rubisco is an enzyme in the calvin cycle which fixates carbon dioxide by incorporating it with other organic molecules
3) oxygen in respiration is found at the end of the ECT, where is picks up the now low energy electrons from the oxidization reactions from the ETC and creates water
4)water is photosynthesis is used to create an electrochemical gradient across the thylakoid membrane and in between the ETC so ATP can be made

48. Name two products of fermentation used commercially.

Ethanol and alcohol.

The ATP synthase in a cell obtains energy for making ATP directly from the flow of H+ across a membrane. This is known as
a. chemiosmosis
b. facilitated diffusion
c. electron transport
d. phosphorylation

chemiosmosis

All the following are required at some stage of photosynthesis, EXCEPT
a. ATP
b. NADPH
c. water
d. oxygen
e. carbon dioxide

oxygen

How many ATP is the cell producing per glucose molecule during
a. aerobic respiration? ____​​​
b. anaerobic respiration?___________

A) 36-38
B) 2

Stage of respiration in which ATP is produced from NADH and FADH2: _________

Oxidative phosphorylation

How many ATPS generated per NADH molecule? ___________ per FADH2 molecule? ______

Per NADH: 2-3
Per FADH2: 1-2

Write the location in the eykaryotic cell (specific location in the organelle)where these stages of respiration take place.

a. Glycolysis: ________________​​
b. Transition reaction: _____________
c. ​Krebs cycle: ____________​​
d. Electron transport chain:______________

A) in the cytoplasm of the cell
B)in the matrix of the mitochondria
C) in the stroma of the chloroplasts
D) in cellular respiration: inner mitochondrial membrane.
in photosynthesis: inner thylakoid membrane

Where in the cell does fermentation take place? ____

In the cytoplasm of the cell (since it is glycolysis)

Will Kreb's cycle take place in the absence of oxygen? ___________

Yes because this step by itself does not require O2

If oxygen is depleted, what alternate path would the respiration process take?

Fermentation

10. The transition reaction involves conversion of pyruvate to ____________

Acetyl CoA

12. The invaginations (infoldings) of the inner mitochondrial membrane are called the _______.

Cristae

11. CO2 is produced during the ________________ reaction and the ____________cycle.

pyruvate oxidation, citric acid cycle

Of the following molecules in the glycolytic pathway (the process of glycolysis), the one with the most chemical energy is _____.
a. pyruvate
b. glucose
c. fructose-6-phosphate
d. fructose-1,6-bisphosphate
e. glyceraldehyde-3-phosphate

D

How many ATP is the cell producing per glucose molecule during
a. aerobic respiration? ____
b. anaerobic respiration?___________

A) 36-38
B) 2-3