$$\text{Small molecule} + \text{Small molecule} + \text{Energy} \rightarrow \text{Larger molecule} + \text{H}_2\text{O}$$

A solution with pH 5 has 100 times more $$\text{H}^+$$ than a solution with pH 7.

Question 1

Which of the following statements best describes the difference between an atom and an element?

Accepted Answer

An element is composed of a single type of atom, while an atom is the smallest chemical unit of matter.

Question 2

Given the atomic number and atomic weight of cobalt (atomic number 27, atomic weight 58.93320), how many neutrons does a typical cobalt atom have?

Accepted Answer

$$58.93320 - 27 = 31.93320$$ neutrons

Question 3

Which of the following best explains why isotopes of the same element have different atomic masses?

Accepted Answer

They have different numbers of neutrons.

Question 4

Which property of water is primarily responsible for its ability to dissolve many ionic compounds?

Accepted Answer

Its polar covalent bonds

Question 5

A sodium atom loses one electron to become a sodium ion. What is the resulting charge and why?

Accepted Answer

It becomes positively charged because it loses an electron.

Question 6

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally due to differences in electronegativity.

Question 7

Which of the following functional groups acts as a base and can pick up a proton from the surrounding solution?

Accepted Answer

Amino group

Question 8

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

Accepted Answer

$$	ext{Small molecule} + 	ext{Small molecule} + 	ext{Energy} ightarrow 	ext{Larger molecule} + 	ext{H}_2	ext{O}$$

Question 9

Which of the following best explains why water has a high surface tension?

Accepted Answer

Because of hydrogen bonds between water molecules

Question 10

Which of the following statements about the pH scale is correct?

Accepted Answer

A solution with pH 5 has 100 times more $$	ext{H}^+$$ than a solution with pH 7.

Question 11

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

Accepted Answer

Catalyzing chemical reactions

Question 12

Which of the following best describes the structure of a phospholipid?

Accepted Answer

A molecule with a hydrophilic head and two hydrophobic tails

Question 13

Which of the following is true about peptide bonds?

Accepted Answer

They are formed by dehydration synthesis reactions between amino acids.

Question 14

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

Accepted Answer

They create electrical differences across cell membranes and are components of enzymes.

Question 15

Which of the following is a property of waxes that distinguishes them from fats and phospholipids?

Accepted Answer

They are completely insoluble in water and lack a hydrophilic head.

Question 16

Which of the following statements about nucleic acids is correct?

Accepted Answer

Hydrogen bonds form between cytosine and guanine, and between adenine and thymine.

Question 17

Which of the following best describes an exchange reaction?

Accepted Answer

A reaction that involves both breaking and forming covalent bonds, with atoms moving from one molecule to another.

Question 18

Which of the following is a trace element essential for life, as discussed in the study materials?

Accepted Answer

Iron

Question 19

Which of the following best explains why organic molecules are so diverse in structure and function?

Accepted Answer

They contain carbon, which can form four covalent bonds and bond with many elements.

Chemistry of Microbiology: Essential Concepts and Structures

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