Question 1

Which of the following best describes the 'fluid mosaic model' of the plasma membrane?

Accepted Answer

A flexible bilayer of phospholipids with embedded proteins that can move laterally, allowing selective permeability.

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will swell and may burst because water moves into the cell to dilute the internal solute.

Question 3

Which process requires energy input in the form of ATP to move substances across the plasma membrane?

Accepted Answer

Active transport

Question 4

A cell is actively transporting $\mathrm{Ca^{2+}}$ ions to the outside, where the concentration is already higher than inside. Which type of transport is this, and what is required?

Accepted Answer

Active transport; requires ATP and a transport protein

Question 5

Which of the following best explains why enzymes are considered biological catalysts?

Accepted Answer

They lower the activation energy barrier, speeding up reactions without being consumed.

Question 6

A patient is given a drug that acts as a noncompetitive inhibitor of an essential metabolic enzyme. What is the most likely effect on the enzyme's activity?

Accepted Answer

The inhibitor binds elsewhere, changing the enzyme's shape and reducing its activity.

Question 7

Which of the following is an example of energy transformation that increases entropy, according to the second law of thermodynamics?

Accepted Answer

A car engine converting gasoline to kinetic energy and heat.

Question 8

Which statement about ATP is correct?

Accepted Answer

ATP hydrolysis releases energy that can be used to drive endergonic reactions in the cell.

Question 9

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of polar molecules down their concentration gradient via transport proteins, without energy input.

Question 10

A cell is placed in a hypertonic solution. What will happen to the cell, and why?

Accepted Answer

It will shrink as water leaves to dilute the external solute.

Question 11

Which of the following is an example of exocytosis?

Accepted Answer

A pancreatic cell releasing insulin into the bloodstream.

Question 12

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Each enzyme has an active site that fits only specific substrates, like a lock and key.

Question 13

Which of the following best describes the role of cofactors and coenzymes in enzyme function?

Accepted Answer

They are nonprotein helpers that bind to the active site and assist in catalysis.

Question 14

A metabolic pathway is regulated by feedback inhibition. Which of the following best explains this process?

Accepted Answer

The end product of the pathway acts as a noncompetitive inhibitor of an early enzyme in the pathway.

Question 15

Which of the following equations correctly represents the hydrolysis of ATP?

Accepted Answer

$\mathrm{ATP} + \mathrm{H_2O} ightarrow \mathrm{ADP} + 	ext{phosphate} + 	ext{energy}$

Question 16

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

Accepted Answer

Ibuprofen binding to the active site of the enzyme involved in prostaglandin production.

Question 17

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water across a selectively permeable membrane from low solute concentration to high solute concentration.

Question 18

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It prevents tight packing of phospholipids, maintaining membrane fluidity.

Question 19

A scientist observes that increasing the temperature above a certain point decreases the rate of an enzyme-catalyzed reaction. What is the most likely explanation?

Accepted Answer

The enzyme is denatured, losing its specific shape and function.

Question 20

Which of the following is an example of an exergonic reaction in a living cell?

Accepted Answer

Hydrolysis of ATP to ADP and phosphate.

Cell Membranes, Transport, and Enzyme Function: Chapter 5 Study Notes

Study Guide - Practice Questions

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