Question 1

Which statement best describes the first law of thermodynamics as it applies to biological systems?

Accepted Answer

Energy is transferred and transformed, but the total amount of energy in the universe remains constant.

Question 2

A cell breaks down glucose in a series of steps, releasing energy. Which type of reaction is this, and what is the sign of $$\Delta G$$?

Accepted Answer

Exergonic; $$\Delta G is $$negative

Question 3

Which of the following best explains why ATP hydrolysis is often coupled to endergonic reactions in cells?

Accepted Answer

ATP hydrolysis provides energy that can make endergonic reactions spontaneous by making the overall $$\Delta G$$ negative.

Question 4

Which of the following is NOT a way enzymes lower the activation energy ($$E_a) of a $$reaction?

Accepted Answer

Increasing the temperature of the cell

Question 5

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and blocking substrate binding

Question 6

Which of the following statements about allosteric regulation is TRUE?

Accepted Answer

Allosteric regulation involves molecules binding to sites other than the active site, which can either activate or inhibit enzyme activity.

Question 7

During cellular respiration, the breakdown of glucose is an example of which type of metabolic pathway?

Accepted Answer

Catabolic

Question 8

Which of the following best describes the second law of thermodynamics in the context of metabolism?

Accepted Answer

Every energy transfer or transformation increases the entropy (disorder) of the universe.

Question 9

If a reaction has $$\Delta G = +3.5$$ kcal/mol, which of the following is TRUE?

Accepted Answer

The reaction is endergonic and requires energy input to proceed.

Question 10

Which of the following is an example of energy coupling in a cell?

Accepted Answer

Using ATP hydrolysis to drive the active transport of ions against their concentration gradient

Question 11

Which of the following factors can denature an enzyme and reduce its activity?

Accepted Answer

Extremely high temperature

Question 12

A graph shows the progress of a reaction with and without an enzyme. What effect does the enzyme have on the activation energy ($$E_a$$)?

Accepted Answer

The enzyme decreases $$E_a$$

Question 13

Which of the following is TRUE about noncompetitive inhibitors?

Accepted Answer

They bind to a site other than the active site and change the enzyme's shape, reducing activity.

Question 14

Which molecule is most likely to function as a coenzyme?

Accepted Answer

Vitamin B6

Question 15

Which of the following best describes induced fit in enzyme action?

Accepted Answer

The enzyme changes shape slightly to better fit the substrate upon binding.

Question 16

Which of the following is a real-world example of enzyme specificity?

Accepted Answer

Trypsin only cleaves peptide bonds next to lysine or arginine residues.

Question 17

Which of the following statements about ATP is correct?

Accepted Answer

ATP hydrolysis releases energy that can be used for cellular work.

Question 18

Which of the following is an example of feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway binds to an enzyme early in the pathway and inhibits its activity.

Question 19

Which of the following is TRUE about the effect of pH on enzyme activity?

Accepted Answer

Each enzyme has an optimal pH, and extremes of pH can denature the enzyme.

Question 20

Which of the following best describes the role of hemoglobin cooperativity in oxygen binding?

Accepted Answer

Binding of one O$$_2$$ molecule increases the affinity of hemoglobin for additional O$$_2$$ molecules.

Metabolism and Enzyme Function: Study Notes for General Biology

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