Question 1

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

Accepted Answer

A molecule consists of two or more atoms held together by chemical bonds, while a compound is a molecule composed of more than one element.

Question 2

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have identical chemical properties because they have the same number of electrons.

Question 3

A sodium atom (Na) has one electron in its outer shell. What happens when it reacts with chlorine (Cl) to form NaCl?

Accepted Answer

Sodium loses its outer electron to chlorine, forming a cation and an anion that attract each other to form an ionic bond.

Question 4

Which property of water is MOST important for its role as a solvent in biological systems?

Accepted Answer

Its ability to form hydrogen bonds due to its polar covalent bonds.

Question 5

What is the main reason decomposition reactions are exothermic?

Accepted Answer

They release energy because the products are more stable than the reactants.

Question 6

Which of the following best explains why carbon atoms form nonpolar covalent bonds with nitrogen atoms?

Accepted Answer

Carbon and nitrogen have similar electronegativities, so electrons are shared equally.

Question 7

A buffer is added to a microbial culture. What is its primary function?

Accepted Answer

To prevent drastic changes in internal pH.

Question 8

Which of the following is TRUE about hydrogen bonds?

Accepted Answer

They help stabilize the 3-D shapes of large biological molecules.

Question 9

Which of the following equations correctly represents the neutralization of hydrochloric acid (HCl) by sodium hydroxide (NaOH)?

Accepted Answer

$$\mathrm{HCl} + \mathrm{NaOH} \rightarrow \mathrm{NaCl} + \mathrm{H}_2\mathrm{O}$$

Question 10

Which of the following statements about ATP is correct?

Accepted Answer

ATP is a nucleotide that serves as the main short-term energy supply for cells.

Question 11

Which functional group is commonly found in amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group ($$-\mathrm{COOH})$$

Question 12

Which of the following best describes the role of phospholipids in cell membranes?

Accepted Answer

They form a bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.

Question 13

Why do microbes living in Arctic water likely have more unsaturated fatty acids in their cell membranes than those living in hot springs?

Accepted Answer

Unsaturated fatty acids increase membrane fluidity at low temperatures.

Question 14

Which of the following is a correct statement about the structure of DNA?

Accepted Answer

DNA is double stranded, with complementary and antiparallel strands.

Question 15

Which of the following is NOT a function of proteins in living organisms?

Accepted Answer

Long-term storage of chemical energy.

Question 16

Which type of chemical bond is responsible for the formation of salts such as NaCl?

Accepted Answer

Ionic bond

Question 17

Which of the following best explains why water can absorb significant amounts of heat energy without changing temperature?

Accepted Answer

Hydrogen bonds between water molecules require energy to break.

Question 18

Which of the following is a product of dehydration synthesis?

Accepted Answer

A water molecule ($$\mathrm{H}_2\mathrm{O})$$

Question 19

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons are found in the outermost shell and determine an atom's chemical behavior.

The Chemistry of Microbiology: Atoms, Bonds, and Water

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