Question 1

Which of the following best describes the pH scale?

Accepted Answer

A negative logarithmic scale measuring the concentration of H$^+$ ions.

Question 2

What is the mathematical formula for calculating pH?

Accepted Answer

$\mathrm{pH} = -\log_{10}[\mathrm{H}^+]$

Question 3

If the concentration of H$^+$ ions in a solution increases, what happens to the pH?

Accepted Answer

The pH decreases.

Question 4

A solution has a pH of 7. What does this indicate about the concentrations of H$^+$ and OH$^-$ ions?

Accepted Answer

The concentration of H$^+$ ions equals the concentration of OH$^-$ ions.

Question 5

Which of the following is a real-world consequence of changes in pH for living organisms?

Accepted Answer

Changes in pH can alter the shape of molecules, affecting their function.

Question 6

Which statement correctly describes acids?

Accepted Answer

Acids are proton donors that increase H$^+$ ion concentration.

Question 7

Which statement correctly describes bases?

Accepted Answer

Bases are proton acceptors that increase OH$^-$ ion concentration.

Question 8

What is the chemical equation for the formation of carbonic acid from carbon dioxide and water?

Accepted Answer

$\mathrm{CO}_2 + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{H}_2\mathrm{CO}_3$

Question 9

Why are buffers important in biological systems?

Accepted Answer

Buffers minimize changes in pH by accepting or donating H$^+$ ions.

Question 10

Which of the following fluids in the human body is likely to contain buffers?

Accepted Answer

Blood, tears, and saliva.

Question 11

If ocean acidification occurs due to increased atmospheric CO$_2$, what is the primary chemical change in seawater?

Accepted Answer

Increase in H$^+$ ion concentration, lowering pH.

Question 12

A buffer system consists of a weak acid and its corresponding base. What happens when excess H$^+$ ions are added to this system?

Accepted Answer

The base component of the buffer will accept H$^+$ ions, minimizing pH change.

Question 13

Which of the following best explains why enzymes are sensitive to pH changes?

Accepted Answer

pH changes can alter the shape of enzymes, affecting their activity.

Question 14

A patient has a blood pH of 7.1. What does this indicate?

Accepted Answer

The blood is more acidic than normal (acidosis).

Question 15

Which of the following is a property of a strong acid?

Accepted Answer

It completely dissociates in water, releasing many H$^+$ ions.

Question 16

If a solution has a pH of 3, what is the concentration of H$^+$ ions?

Accepted Answer

$[\mathrm{H}^+] = 1 	imes 10^{-3}\ \mathrm{M}$

Question 17

Which of the following is a correct statement about the relationship between pH and OH$^-$ ion concentration?

Accepted Answer

As OH$^-$ ion concentration increases, pH increases.

Question 18

Which of the following is an example of a buffer system in the human body?

Accepted Answer

Carbonic acid-bicarbonate system in blood.

Question 19

A scientist adds a strong base to a solution, increasing the OH$^-$ ion concentration. What is the expected effect on pH?

Accepted Answer

The pH will increase.

Understanding pH, Acids, Bases, and Buffers in Biology

Study Guide - Practice Questions