Question 1

Which property of water allows it to dissolve ionic compounds like sodium chloride (NaCl) in the human body?

Accepted Answer

Water is a polar molecule, allowing it to surround and separate ions.

Question 2

What is the main reason why ice floats on liquid water?

Accepted Answer

Hydrogen bonds in ice create a rigid lattice structure, making it less dense than liquid water.

Question 3

Which of the following best describes a buffer in biological systems?

Accepted Answer

A buffer is a substance that minimizes changes in pH when acids or bases are added.

Question 4

A solution has a pH of 5. What does this indicate about the concentration of hydrogen ions ($$[H^+]) in $$the solution?

Accepted Answer

The solution is acidic with a higher $$[H^+]$$ than pure water.

Question 5

Which of the following is a correct representation of the hydrolysis reaction of a disaccharide?

Accepted Answer

$$C_{12}H$$_{22}$$O_{11} + H_2O \rightarrow 2C_6H_{12}O_6$

Question 6

Which of the following statements about saturated and unsaturated fatty acids is TRUE?

Accepted Answer

Saturated fatty acids have no double bonds and are straight, allowing them to pack closely together.

Question 7

Which of the following best explains why proteins can be denatured by high temperatures or changes in pH?

Accepted Answer

High temperatures and pH changes disrupt hydrogen bonds and ionic interactions in secondary and tertiary structures.

Question 8

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

Accepted Answer

Providing structural support to bones.

Question 9

Which of the following best describes the difference between a hydrogen atom and a hydrogen ion?

Accepted Answer

A hydrogen atom has one proton and one electron; a hydrogen ion ($$H^+) $$has only one proton.

Question 10

Which of the following best explains why carbon is the backbone of organic molecules?

Accepted Answer

Carbon can form up to four strong covalent bonds with other atoms, allowing for diverse molecular structures.

Question 11

A patient’s blood pH drops from 7.4 to 7.1. What is the physiological significance of this change?

Accepted Answer

The blood has become more acidic, which can disrupt transport and enzyme function.

Question 12

Which of the following is a correct description of a phospholipid?

Accepted Answer

A molecule with a polar head and two nonpolar fatty acid tails, forming the primary structure of cell membranes.

Question 13

Which of the following best describes the role of ATP in cells?

Accepted Answer

ATP is a universal energy carrier, releasing energy when its phosphate bonds are broken: $$ATP ightarrow ADP + P + 	ext{energy}$$

Question 14

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

Accepted Answer

It includes alpha helices and beta pleated sheets stabilized by hydrogen bonds.

Question 15

Which of the following best explains why enzymes are necessary for life?

Accepted Answer

Enzymes are proteins that speed up biochemical reactions by lowering activation energy, allowing life-sustaining reactions to occur rapidly.

Question 16

Which of the following is a correct example of dehydration synthesis?

Accepted Answer

Joining two monosaccharides to form a disaccharide and releasing water: $$C_6H_{12}O_6$ + C_6H_{12}O_6$ \rightarrow C$$_{12}$$H_{22}O$$_{11} + H_2O$

Question 17

Which of the following statements about free radicals is correct?

Accepted Answer

Free radicals are atoms or molecules with unpaired electrons that can damage proteins, lipids, and DNA.

Question 18

Which of the following best describes the relationship between DNA, RNA, and proteins?

Accepted Answer

DNA contains instructions for RNA, which then directs protein synthesis.

Question 19

Which of the following is a correct statement about isotopes?

Accepted Answer

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

Chemistry of Life: Essential Concepts for Human Biology

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