Question 1

Which statement best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

The plasma membrane consists of a phospholipid bilayer with proteins and other molecules embedded, allowing lateral movement.

Question 2

A red blood cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will shrink as water moves out of the cell into the hypertonic solution.

Question 3

Which of the following molecules can most easily diffuse through the plasma membrane without assistance?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 4

If a cell is placed in a hypotonic solution, what is the expected outcome for a plant cell?

Accepted Answer

The cell will become turgid as water enters, which is beneficial for plant structure.

Question 5

Which process requires energy input from the cell and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 6

The sodium-potassium pump ($$\mathrm{Na^+/K^+}$$ pump) moves ions across the plasma membrane. Which statement is correct about its function?

Accepted Answer

It moves sodium ions out and potassium ions into the cell, using ATP.

Question 7

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient with the help of membrane proteins, without energy input.

Question 8

Which type of endocytosis involves the cell engulfing large particles or microorganisms?

Accepted Answer

Phagocytosis

Question 9

A cell uses exocytosis to release insulin into the bloodstream. What is the main function of exocytosis?

Accepted Answer

To expel substances from the cell by vesicle fusion with the plasma membrane.

Question 10

Which statement correctly compares passive and active transport?

Accepted Answer

Passive transport moves substances down their concentration gradient without energy; active transport moves substances against their gradient using energy.

Question 11

Which of the following is an example of kinetic energy in a biological system?

Accepted Answer

Movement of cilia on a cell surface

Question 12

Which law of thermodynamics states that energy cannot be created or destroyed, only transformed?

Accepted Answer

First law of thermodynamics

Question 13

Which reaction is exergonic and releases energy?

Accepted Answer

Breakdown of glucose during cellular respiration

Question 14

Energy coupling in cells is primarily achieved through which molecule?

Accepted Answer

ATP ($$\mathrm{C$$_{10}$$H_{16}N_5O$$_{13}$$P_3$$}$)

Question 15

What is the role of enzymes in chemical reactions?

Accepted Answer

They lower the activation energy, speeding up the reaction.

Question 16

Which of the following best describes activation energy?

Accepted Answer

The energy required to start a chemical reaction.

Question 17

A cell is placed in a solution with 0.9% NaCl. The cytoplasm also contains 0.9% NaCl. What is the tonicity of the solution relative to the cell?

Accepted Answer

Isotonic

Question 18

Which scenario best illustrates the second law of thermodynamics in biological systems?

Accepted Answer

Energy transformations in cells always increase the overall disorder (entropy) of the system.

Question 19

Which process is an example of endergonic (anabolic) reaction?

Accepted Answer

Synthesis of proteins from amino acids

Question 20

A scientist measures the concentration of a solute on both sides of a completely permeable membrane. If the initial concentrations are 0.2 M on one side and 0.8 M on the other, what will be the equilibrium concentration after diffusion?

Accepted Answer

$$0.5\ \mathrm{M}$$

Cell Membrane Structure, Transport Mechanisms, and Energy in Biological Systems

Study Guide - Practice Questions

Study Guide - Flashcards