Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

$$[H^+] = 1 \times 10$$^{-4}$$ \ \mathrm{mol/L}$$

Question 1

Which of the following best explains why water is considered an excellent solvent in biological systems?

Accepted Answer

Water molecules are polar, allowing them to surround and separate ions and polar molecules.

Question 2

A patient is given a radioactive isotope for a diagnostic scan. Which property of isotopes makes this possible?

Accepted Answer

Isotopes have the same chemical properties but different numbers of neutrons, allowing some to be radioactive.

Question 3

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is any group of atoms bonded together, while a compound contains atoms of two or more different elements.

Question 4

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ \ \mathrm{mol/L}$$

Question 5

Which of the following best describes the role of enzymes in metabolic reactions?

Accepted Answer

Enzymes lower the activation energy, allowing reactions to proceed at body temperature.

Question 6

A patient is experiencing muscle cramps due to an electrolyte imbalance. Which of the following best explains why maintaining proper electrolyte levels is critical for physiological function?

Accepted Answer

Electrolytes conduct electrical currents necessary for nerve and muscle function.

Question 7

Which of the following is an example of a synthesis (anabolic) reaction in the body?

Accepted Answer

The combination of amino acids to form a protein.

Question 8

If a strong acid such as hydrochloric acid ($$\mathrm{HCl}) is $$added to water, what happens to the pH and why?

Accepted Answer

The pH decreases because $$\mathrm{HCl}$$ releases hydrogen ions.

Question 9

Which of the following best explains why water has a high heat capacity?

Accepted Answer

Hydrogen bonds between water molecules require significant energy to break.

Question 10

A buffer system in the blood helps maintain pH homeostasis. Which of the following best describes how a buffer works?

Accepted Answer

A buffer stabilizes pH by either removing or releasing hydrogen ions as needed.

Question 11

Which of the following statements about ATP (adenosine triphosphate) is correct?

Accepted Answer

ATP stores energy in the bonds between its phosphate groups.

Question 12

A solution is described as alkaline. Which of the following pH values would best represent this solution?

Accepted Answer

pH = 8.5

Question 13

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the electrical attraction between oppositely charged ions.

Question 14

A patient with blood pH of 7.0 is at risk for which of the following conditions?

Accepted Answer

Acidosis, which can result in coma.

Question 15

Which of the following is a property of organic compounds?

Accepted Answer

They contain carbon covalently bonded to other elements, often including hydrogen.

Question 16

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally, resulting in partial charges.

Question 17

Which of the following reactions is an example of a decomposition reaction?

Accepted Answer

$$AB \rightarrow A + B$$

Question 18

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

Accepted Answer

They lower the activation energy and are not permanently changed by the reaction.

Question 19

A patient is given an intravenous solution of 0.9% NaCl. Why is this solution considered an electrolyte?

Accepted Answer

It dissociates in water to release ions that can conduct electricity.

Question 20

Which of the following best describes the relationship between chemicals and cells in the human body?

Accepted Answer

Biochemical building blocks such as carbohydrates, lipids, proteins, and nucleic acids form the structure and function of cells.

Chemical Level of Organization: Foundations for Anatomy & Physiology

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