Question 1

Which of the following statements best explains why sodium (Na) forms a cation when it reacts with chlorine (Cl) to make table salt?

Accepted Answer

Sodium has one electron in its outer shell and loses it to achieve a stable, filled valence shell, becoming positively charged.

Question 2

A patient is exposed to a radioisotope with a half-life of 6 hours. If the initial dose is 100 mg, how much of the radioisotope remains after 18 hours? Use the formula $$N = N_0$ 	imes (\frac{1}{2}$$)^{\frac{t}$${t_{1/2}}}.$$

Accepted Answer

12.5 mg

Question 3

Which property of water allows it to moderate temperature changes in the human body, and what is the underlying molecular reason?

Accepted Answer

High specific heat; hydrogen bonds between water molecules must be broken to increase temperature.

Question 4

Which of the following best describes the difference between a polar and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity, while nonpolar covalent bonds involve equal sharing.

Question 5

A solution is prepared by dissolving 10 grams of glucose in enough water to make 100 mL of solution. What is the mass/volume percent concentration of glucose in this solution?

Accepted Answer

$$10\%$$

Question 6

Which of the following molecules is amphipathic and forms the main component of cell membranes?

Accepted Answer

Phospholipid

Question 7

A protein is exposed to a pH of 2, far below its optimal pH. What is most likely to happen to the protein’s structure and function?

Accepted Answer

The protein will denature, losing its three-dimensional shape and biological activity.

Question 8

Which of the following best describes the relationship between pH and hydrogen ion concentration $$[H^+] in a $$solution?

Accepted Answer

pH decreases as $$[H^+]$$ increases, following the formula $$	ext{pH} = -\log_{10}[H^+].$$

Question 9

Which of the following is NOT a function of lipids in the human body?

Accepted Answer

Enzyme catalysis

Question 10

A molecule of DNA contains the nitrogenous bases adenine, cytosine, guanine, and thymine. Which base is NOT found in DNA, and what is its role in RNA?

Accepted Answer

Uracil; replaces thymine in RNA.

Question 11

Which intermolecular force is responsible for the surface tension observed in water?

Accepted Answer

Hydrogen bonding between water molecules.

Question 12

Which of the following best describes the process of dehydration synthesis?

Accepted Answer

Combining monomers by removing a —H from one and an —OH from another, forming a covalent bond and a water molecule.

Question 13

A patient’s blood plasma contains proteins ranging in size from 1 to 100 nanometers. What type of mixture is this?

Accepted Answer

Colloid

Question 14

Which of the following statements about amino acids is correct?

Accepted Answer

Amino acids differ in their R group, which determines their chemical properties.

Question 15

Which of the following is a correct description of the quaternary structure of a protein?

Accepted Answer

It is the structure formed by two or more polypeptide chains interacting.

Question 16

Which of the following is a real-life example of a suspension in the human body?

Accepted Answer

Blood cells within plasma

Question 17

Which of the following statements about isotopes is TRUE?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 18

Which of the following best explains why hydrophobic substances do not dissolve in water?

Accepted Answer

Hydrophobic substances are nonpolar and are excluded from water, which is polar.

Question 19

Which of the following is a function of buffers in the human body?

Accepted Answer

Buffers prevent drastic changes in pH when excess acid or base is added.

Question 20

A solution contains 0.5 moles of NaCl dissolved in 1 kilogram of water. What is the molality of the solution?

Accepted Answer

$$0.5\ 	ext{mol/kg}$$

Chapter 2: Chemistry Comes Alive – Foundations for Anatomy & Physiology

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