Question 1

Which of the following statements best explains why sodium (Na) and chlorine (Cl) form an ionic bond to create sodium chloride (NaCl)?

Accepted Answer

Sodium donates an electron to chlorine, resulting in oppositely charged ions that attract each other.

Question 2

A patient is given a radioactive isotope for diagnostic imaging. Which property of isotopes makes them useful for this purpose?

Accepted Answer

Isotopes have the same number of protons 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 two or more atoms chemically combined, while a compound is two or more different atoms chemically combined.

Question 4

Which of the following best explains why water (H$$_2O) is $$considered a polar molecule?

Accepted Answer

The oxygen atom attracts electrons more strongly, creating a partial negative charge near oxygen and a partial positive charge near hydrogen.

Question 5

A solution has a pH of 4. How many times more acidic is it than a solution with a pH of 6?

Accepted Answer

100 times

Question 6

Which of the following best describes the role of buffers in the human body?

Accepted Answer

Buffers maintain homeostasis by resisting changes in pH.

Question 7

Which of the following is a correct statement about saturated and unsaturated fats?

Accepted Answer

Saturated fats have no double bonds between carbon atoms and are usually solid at room temperature.

Question 8

A protein is exposed to high heat and loses its functional shape. This process is called:

Accepted Answer

Denaturation

Question 9

Which of the following best explains why cellulose is an important dietary component for humans, even though it cannot be digested?

Accepted Answer

Cellulose adds fiber to the diet, aiding in digestive health.

Question 10

Which of the following best describes the structure of a nucleotide, the building block of nucleic acids?

Accepted Answer

A nucleotide consists of a phosphate group, a five-carbon sugar, and a nitrogenous base.

Question 11

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

Accepted Answer

Enzymes lower the activation energy required for chemical reactions, allowing them to occur at body temperature.

Question 12

A molecule of ATP (adenosine triphosphate) releases energy when:

Accepted Answer

A phosphate group is removed, converting ATP to ADP.

Question 13

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

Accepted Answer

It involves hydrogen bonding that forms alpha helices and beta sheets.

Question 14

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded and contains deoxyribose; RNA is usually single-stranded and contains ribose.

Question 15

A patient is found to have a blood pH of 7.1. Which of the following best describes this condition?

Accepted Answer

The blood is acidic.

Question 16

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

Accepted Answer

Carbon can form up to four covalent bonds, allowing for a variety of stable, complex structures.

Question 17

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

Accepted Answer

Joining two amino acids to form a dipeptide and releasing a molecule of water.

Question 18

Which of the following best describes the function of phospholipids in the body?

Accepted Answer

They are the main component of cell membranes, forming a bilayer.

Question 19

A molecule has the formula C$$_6H$_{12}O$_6. $$Which class of organic molecules does it most likely belong to?

Accepted Answer

Carbohydrate

Question 20

Which of the following best explains why electrolytes are important for body function?

Accepted Answer

They conduct electrical currents, which are essential for nerve impulses and muscle contraction.

BIO 141 Chapter 2: The Molecules of Cells – Study Notes

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