$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which of the following best explains why water is essential for life, based on its chemical properties?

Accepted Answer

Water's polarity allows it to form hydrogen bonds, making it an excellent solvent for polar and ionic substances.

Question 2

A patient is diagnosed with metabolic acidosis. Which buffer system is most important in stabilizing the pH of their blood?

Accepted Answer

Carbonic acid–bicarbonate buffer system: $$ \mathrm{CO_2$ + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + $$HCO_3$$^-} $$

Question 3

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy, speeding up biochemical reactions without being changed themselves.

Question 4

Which type of chemical bond is primarily responsible for the secondary structure of proteins?

Accepted Answer

Hydrogen bonds

Question 5

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

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 6

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

Accepted Answer

A molecule is two or more atoms joined by shared electrons; a compound is two or more atoms of different elements.

Question 7

Which of the following is an example of a decomposition reaction important in physiology?

Accepted Answer

Hydrolysis of ATP to ADP: $$ \mathrm{ATP + H_2O \rightarrow ADP + P_i + energy} $$

Question 8

Which of the following statements about lipids is correct?

Accepted Answer

Steroids are a type of lipid with a four-ring structure, such as cholesterol.

Question 9

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

Accepted Answer

A water molecule is removed to form a bond between monomers.

Question 10

Which of the following is true regarding the structure of DNA?

Accepted Answer

DNA consists of two complementary strands held together by hydrogen bonds between base pairs.

Question 11

A patient is given a solution with a pH of 9. Which of the following best describes this solution?

Accepted Answer

It is basic (alkaline) and has a higher concentration of $$OH^-$$ ions than $$H^+$$ ions.

Question 12

Which of the following best explains why enzymes are specific to their substrates?

Accepted Answer

The active site of an enzyme has a unique shape that only fits specific substrates.

Question 13

Which of the following is a correct statement about the structure of amino acids?

Accepted Answer

Each amino acid contains a central carbon, a hydrogen atom, a carboxyl group, an amino group, and a unique R group.

Question 14

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have no double bonds; unsaturated fatty acids have one or more double bonds in the hydrocarbon tail.

Question 15

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

Accepted Answer

Acting as enzymes, antibodies, and components of plasma membranes

Question 16

Which of the following best describes the process of phosphorylation?

Accepted Answer

The addition of a phosphate group to another molecule, often producing a high-energy compound

Question 17

Which of the following is a correct example of an exchange reaction in the body?

Accepted Answer

$$ \mathrm{CO_2$ + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + $$HCO_3$$^-} $$

Question 18

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP stores energy in its high-energy phosphate bonds and releases it when converted to ADP.

Question 19

Which of the following is true about the quaternary structure of proteins?

Accepted Answer

It is the result of interactions between two or more polypeptide chains forming a protein complex.

Chapter 2: The Chemical Level of Organization – Study Notes

Study Guide - Practice Questions