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

Question 1

Which of the following best explains why water is an excellent solvent for many biological molecules?

Accepted Answer

Water molecules are polar, allowing them to surround and separate ions and polar molecules.

Question 2

A radioactive isotope of carbon, carbon-14, is used in radiometric dating. Which of the following statements about carbon-14 is correct?

Accepted Answer

It has 6 protons and 8 neutrons in its nucleus.

Question 3

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

Accepted Answer

Hydrogen bonds

Question 4

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

Accepted Answer

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

Question 5

Which of the following best describes a dehydration synthesis reaction?

Accepted Answer

A reaction in which two molecules are joined together with the removal of a water molecule.

Question 6

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

Accepted Answer

Unsaturated fatty acids increase membrane fluidity at low temperatures.

Question 7

Which of the following is a function of carbohydrates in cells?

Accepted Answer

Providing long-term energy storage

Question 8

Which of the following statements about ionic bonds is correct?

Accepted Answer

Ionic bonds result from the attraction between oppositely charged ions.

Question 9

Which of the following best explains why decomposition reactions are exothermic?

Accepted Answer

They release energy as bonds in larger molecules are broken to form smaller, more stable products.

Question 10

Which of the following is NOT a characteristic of water that makes it essential for life?

Accepted Answer

It is a nonpolar molecule that cannot form hydrogen bonds.

Question 11

Which of the following statements about ATP (adenosine triphosphate) is correct?

Accepted Answer

ATP stores energy in the bonds between its phosphate groups.

Question 12

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

Accepted Answer

A substance that prevents drastic changes in pH by absorbing or releasing H+ ions.

Question 13

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

Accepted Answer

The two strands are complementary and antiparallel.

Question 14

Which of the following functional groups is found in all amino acids?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 15

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

Accepted Answer

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

Question 16

Which of the following is a property of phospholipids that is critical for cell membrane structure?

Accepted Answer

They have both hydrophilic heads and hydrophobic tails.

Question 17

Which of the following statements about nucleotides is correct?

Accepted Answer

Nucleotides are composed of a phosphate group, a pentose sugar, and a nitrogenous base.

Question 18

Which of the following best explains why salts are important in biological systems?

Accepted Answer

They dissociate into electrolytes that help maintain electrical differences across cell membranes.

Question 19

Which of the following is true regarding the formation of a peptide bond?

Accepted Answer

It is a covalent bond formed by dehydration synthesis between the carboxyl group of one amino acid and the amino group of another.

Chapter 2: The Chemistry of Microbiology - Structured Study Notes

Study Guide - Practice Questions