bio311c exam 3 - dr. sata

Q8) Select all the answers that describe the process of respiration. Wrong answer choices have negative points.

- Exergonic process - Exothermic process - Catabolic process

Q6) Which of the following mechanisms are used to regulate enzyme activity? Select all that apply.

- Phosphorylation - Feedback regulation - Activators that bind reversibly and stimulate the enzyme activity temporarily - Activators that bind reversibly and block the enzyme activity temporarily

Q20) Which of the following are common properties of C4 and CAM plants? Select all that apply. Wrong answer choices have negative points. Both C4 and CAM plants can ___________.

- perform Calvin/Benson Cycle - use PEP carboxylase to initially fix CO2 - minimize photorespiration

The ∆G for a particular enzyme-catalyzed reaction is -20 kcal/mol. If the amount of enzyme in the reaction is doubled, what will be the ∆G for the new reaction?

-20 kcal/mol

Q9) Understand the given equation and answer the following question. Pyruvate + CoA + NAD+ --> Acetyl CoA + CO2 + NADH This reaction of NAD+ becoming NADH is considered as a/an ____________, and the NAD+ acts as a/an __________ agent.

1) reduction, 2) oxidizing

Q5) Any accidental drinking of methanol can make one blind or cause death. A person who drank methanol by mistake is given ethanol as an antidote. Shown below is the enzyme reaction of Alcohol Dehydrogenase (ADH) on these two substrates. Ethanol + ADH --> Acetaldehyde Methanol + ADH --> Formaldehyde How does this treatment work?

ADH prefers ethanol and acetaldehyde can be converted to a non-toxic molecule.

Q1) Which of the following is an example of an exergonic reaction (1st example) that powers the synthesis of an endergonic reaction (second example)?

ATP Hydrolysis (exergonic) and photosynthesis (endergonic)

Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

ATP and NADPH

Q4) Consider the following graph and conclude the nature of the enzyme. Phosphofructokinase (PFK) is made of 4 subunits and is also a key regulatory enzyme of glycolysis. Shown below is the response of PFK to the substrate concentration (Fructose 6-phosphate). What is the nature of this enzyme and what is the role of ATP in this reaction?

Allosteric enzyme and inhibitor

Q19) Which of the following are inputs of the Calvin-Benson cycle? Select all that apply. Wrong answers will have negative points.

CO2 ATP NADPH

Q14) What is the exergonic process that directly drives the endergonic process of ATP synthesis in oxidative phosphorylation?

Chemiosmosis and proton motive force

Q3) The reactions shown above are two types of enzyme reactions that occur in a cell. Which reaction will require ATP hydrolysis to occur? (Picture 1 is an endergonic reaction and picture 2 is an exergonic reaction)

Endergonic reaction

Q15) Even though oxygen is not an input for glycolysis, acetyl CoA formation, and Krebs cycle, these reactions will come to a grinding halt if oxygen is not present for oxidative phosphorylation, because ________.

NAD+ and FAD are not regenerated for these processes to continue

Which of the following molecules donates electrons directly to the electron transport chain at the highest energy level?

NADH

In addition to ATP, what are the products of glycolysis?

NADH and pyruvate

Q12) Why does Oxidative Phosphorylation make so much more ATP (32-34 ATP/glucose) compared to Substrate Level Phosphorylation (2 + 2 ATP/glucose)?

Oxidative phosphorylation utilizes all the NADH and FADH2 generated in Glycolysis, Acetyl CoA formation and Krebs Cycle to make lot of ATP

Q7) Which output(s) of glycolysis enters mitochondria and is/are used in the acetyl CoA formation?

Pyruvate

Q2) The second law of thermodynamics states that every energy transfer and transformation results in increased randomness in the universe. Living organisms consume energy and release energy. They transfer and transform various forms of energy but they still maintain structure and order. Despite this, living organisms do not become more random or disorganized. This can occur because ___________________.

The randomness happens in their surroundings

Q16) What is the purpose of the electron shuttle in the respiration process?

To carry electrons from cytoplasmic NADH to mitochondrial FAD or NAD+

A reduction in the amount of NADP+ available in plant cells in the light will ultimately result in which of the following effects?

a decrease in the rate of linear electron flow

The oxygen consumed during cellular respiration is involved directly in which process or event?

accepting electrons at the end of the electron transport chain

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?

as a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth

Which of the following statements is true of enzymes?

enzymes generally increase the rate of chemical reactions by lowering activation energy barriers

The cellular process of breaking down large molecules into smaller ones is defined as?

catabolism

Zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. The zinc most likely functions as a(n)

cofactor necessary for enzyme activity

Where does glycolysis occur in animal cells?

cytosol

Which of the following is a statement of the first law of thermodynamics?

energy cannot be created or destroyed

The mechanism by which the end product of a metabolic pathway inhibits an enzyme that catalyzes an earlier step in the pathway is most precisely described as

feedback inhibition

In chemiosmosis in mitochondria, protons flow from the intermembrane space into the matrix. In what direction do protons flow during chemiosmosis in chloroplasts?

from the thylakoid space to into the stroma

Which of the following indicates a primary path by which electrons travel downhill energetically during aerobic respiration?

glucose → NADH → electron transport chain → oxygen

An aminoacyl-tRNA synthetase is the enzyme that catalyzes the attachment of a particular amino acid to its corresponding tRNA. This reaction requires energy from ATP. The enzyme initially binds the amino acid and ATP, but it is unable to bind the tRNA at this point. Which of the following would be a likely next step in the reaction by which the enzyme ultimately binds the tRNA and attaches the amino acid?

hydrolysis of ATP phosphorylates the amino acid, which results in a conformational change in the active site that allows the tRNA to bind

As a result of an oxidation-reduction reaction, how is the oxidizing agent changed?

it gains electrons and gains potential energy

Q18) Even though the light is not an input in the Calvin-Benson cycle, CAM plants fix CO2 in the night time by PEP Carboxylase and wait until daytime to perform the Calvin-Benson cycle because__________.

it needs ATP and NADPH from the light reactions

The complete reactions of cellular respiration in the presence of oxygen (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy) result in which of the following?

oxidation of C6H12O6 and reduction of O2

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

What is the source of the energy used to generate the proton gradient across the inner mitochondrial membrane?

redox reactions in the electron transport chain

Q10) Krebs cycle makes only 2 ATP per glucose. Most of the energy used in the oxidation of acetyl CoA is used to ___________.

reduce NAD+ and FAD

Q13) The main purpose of alcohol fermentation is to ___________ to continue make ATP without any oxygen.

regenerate NAD+

Which of the following reactions produces the oxygen released by photosynthesis?

splitting of water molecules

Q17) Photorespiration occurs during hot and dry weather conditions. During this time plants must conserve water by closing their _________.

stomates

Where does the Calvin cycle take place?

stroma of the chloroplast

Q11) Creatine phosphate is used as a supplement during intense workouts. The reaction shown below illustrates what happens in the muscle cell deprived of oxygen. This reaction is a/an ________ and it is catalyzed by _______. Creatine phosphate + ADP --> Creatine + ATP

substrate level phosphorylation... kinase

Which chemical process generates the ATP produced in the citric acid cycle?

substrate-level phosphorylation

Which of the following statements best describes the induced fit model of enzyme activity?

the binding of substrate changes the conformation of the active site to bind substrate more tightly

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask.

the concentration of dissolved oxygen in the flask with algae will be higher in the light but lower in the dark

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

the light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP, ℗i, and NADP+ to the light reactions

Which of the following statements is true for all exergonic reactions?

the reaction proceeds with a net release of free energy

How would you predict that doubling the atmospheric CO2 concentration would affect C3 plants?

they will experience increased rates of photosynthesis and growth

Where are ATP synthase complexes located in a plant cell?

thylakoid membranes and inner mitochondrial membranes

What is the primary function of the Calvin cycle?

to produce simple sugars from carbon dioxide