Question 1

Which of the following best explains why table salt (NaCl) dissolves easily in water?

Accepted Answer

Because water forms hydration spheres around the Na+ and Cl- ions, separating them due to electrostatic attraction.

Question 2

A researcher is comparing two drug candidates for binding to a cell receptor. Molecule A has a $K_d$ of 4.9, and Molecule B has a $K_d$ of 0.8. Which molecule has the higher affinity for the receptor, and why?

Accepted Answer

Molecule B, because a lower $K_d$ indicates higher affinity.

Question 3

Which of the following is a correct statement about the structure and function of biological membranes?

Accepted Answer

The phospholipid bilayer has hydrophilic regions on the surfaces and hydrophobic tails in the interior, allowing selective permeability.

Question 4

Which of the following best describes the difference between covalent and ionic bonds?

Accepted Answer

Covalent bonds involve sharing pairs of electrons between atoms, while ionic bonds involve electrostatic attraction between charged ions.

Question 5

A solution has a hydrogen ion concentration of $[H^+] = 1 	imes 10^{-5} \ M$. What is the pH of this solution?

Accepted Answer

$pH = 5$

Question 6

Which of the following functional groups is correctly matched with its structure?

Accepted Answer

Hydroxyl group: $-OH$

Question 7

Which of the following best explains why proteins can have such diverse functions in the body?

Accepted Answer

Proteins have complex and varied shapes due to their primary, secondary, tertiary, and quaternary structures.

Question 8

A patient has a blood pH of 7.2. Which of the following statements is correct?

Accepted Answer

The blood is acidic because the pH is below 7.4, the normal physiological pH.

Question 9

Which organelle would you expect to be increased in number in a cell specialized for testosterone production?

Accepted Answer

Smooth endoplasmic reticulum

Question 10

Which of the following best describes the law of mass action as it applies to protein-ligand binding?

Accepted Answer

At equilibrium, the rate of binding equals the rate of unbinding, and the ratio $\frac{[PL]}{[P][L]}$ remains constant.

Question 11

Which of the following is a correct statement about the role of hydrogen bonds in biological molecules?

Accepted Answer

Hydrogen bonds are responsible for the secondary structure of proteins and the structure of DNA.

Question 12

A glucose molecule entering the body in orange juice will pass through which order of fluid compartments as it is absorbed?

Accepted Answer

Plasma → interstitial → intracellular

Question 13

Which of the following best describes the difference between fibrous and globular proteins?

Accepted Answer

Fibrous proteins have elongated shapes and provide structural support, while globular proteins are compact and often serve as enzymes or transporters.

Question 14

Which of the following best explains why a solution with pH 6 is more acidic than a solution with pH 8?

Accepted Answer

Because the solution with pH 6 has 100 times more $[H^+]$ than the solution with pH 8.

Question 15

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Forming the phospholipid bilayer

Question 16

Which of the following best describes the role of cofactors in protein function?

Accepted Answer

Cofactors are required for an active binding site and are usually ions or small organic molecules.

Question 17

Which of the following best explains why nonpolar molecules are hydrophobic?

Accepted Answer

Nonpolar molecules do not dissolve in water because they cannot form hydration spheres or hydrogen bonds with water.

Question 18

Which of the following best describes the function of the Golgi apparatus?

Accepted Answer

It sorts, modifies, and packages proteins into vesicles for transport.

Question 19

Which of the following statements about protein-ligand binding is correct?

Accepted Answer

The specificity of protein-ligand binding depends on molecular complementarity.

Molecular Interactions, Chemical Bonds, and Cellular Compartmentation in Human Physiology

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