Question 1

Which statement best describes the 1st Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy can be transformed from one form to another, but cannot be created or destroyed.

Question 2

A cell is synthesizing a complex molecule from simpler reactants. According to the 2nd Law of Thermodynamics, which of the following is true about this process?

Accepted Answer

The process decreases the entropy of the system and requires energy input.

Question 3

Which of the following reactions is most likely to occur spontaneously?

Accepted Answer

A reaction where the reactants have higher free energy than the products.

Question 4

Which equation correctly represents the change in Gibbs free energy for a reaction?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 5

During cellular respiration, glucose is oxidized. Which statement best describes what happens in this redox reaction?

Accepted Answer

Glucose loses electrons and is oxidized; oxygen gains electrons and is reduced.

Question 6

Why are organic molecules with many C-H bonds considered good sources of energy?

Accepted Answer

C-H bonds have high potential energy due to shared electrons being equally distributed.

Question 7

What is the energy input required to initiate a chemical reaction called?

Accepted Answer

Activation energy ($$E_A)$$

Question 8

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The enzyme's active site has a unique three-dimensional shape that only fits specific substrates.

Question 9

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and blocking substrate binding.

Question 10

Which of the following transport processes moves molecules UP their concentration gradient and requires ATP?

Accepted Answer

Active transport (e.g., sodium/potassium pump)

Question 11

Which process increases entropy in a cell membrane system?

Accepted Answer

Passive diffusion of molecules down their concentration gradient

Question 12

A cell is placed in a solution with a high concentration of sodium ions. Which transport protein would help move sodium ions into the cell against their concentration gradient?

Accepted Answer

Carrier protein involved in active transport

Question 13

Which of the following best describes the function of the sodium/potassium pump?

Accepted Answer

It uses ATP to move sodium out of the cell and potassium into the cell, creating an electrochemical gradient.

Question 14

Which of the following statements about exergonic and endergonic reactions is correct?

Accepted Answer

Exergonic reactions have a negative $$\Delta G$$ and can occur spontaneously.

Question 15

Which of the following is NOT a function of ATP in cellular metabolism?

Accepted Answer

Storing genetic information for protein synthesis.

Question 16

A patient has a fever of 41°C (above normal body temperature). How might this affect the activity of most human enzymes?

Accepted Answer

Enzyme activity may decrease due to denaturation of the enzyme's structure.

Question 17

Which of the following best describes an electrochemical gradient?

Accepted Answer

A combination of a chemical concentration gradient and an electrical charge difference across a membrane.

Question 18

Which of the following scenarios is an example of energy coupling in cells?

Accepted Answer

The hydrolysis of ATP is used to drive an endergonic reaction.

Question 19

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It moves molecules down their concentration gradient with the help of transport proteins.

Question 20

Which of the following best explains why both exergonic and endergonic reactions may require an initial energy input?

Accepted Answer

The activation energy ($$E_A) is $$needed to reach the transition state, even if the reaction is overall spontaneous.

Thermodynamics, Energetics, and Membrane Transport in Cells

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