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

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

Question 1

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

Accepted Answer

Water molecules have two polar covalent bonds, allowing them to interact with charged and polar substances.

Question 2

A radioactive isotope of carbon, carbon-14, is used in radiometric dating. What makes carbon-14 different from carbon-12?

Accepted Answer

Carbon-14 has more neutrons than carbon-12.

Question 3

Which type of chemical bond is primarily responsible for stabilizing the three-dimensional structure of large biological molecules such as proteins and nucleic acids?

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}$$ M

Question 5

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical behavior of an atom.

Question 6

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

Accepted Answer

Unsaturated fatty acids increase membrane fluidity at low temperatures.

Question 7

Which of the following is a correct description of a dehydration synthesis reaction?

Accepted Answer

It forms larger, more complex molecules by removing a water molecule.

Question 8

Which functional group is found in all amino acids and is essential for peptide bond formation?

Accepted Answer

Amino group ($$-NH_2$)

Question 9

What is the main 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 10

Which of the following best describes the role of buffers in microbial metabolism?

Accepted Answer

Buffers prevent drastic changes in internal pH, maintaining homeostasis.

Question 11

Which of the following bonds is the strongest in biological systems?

Accepted Answer

Covalent bond

Question 12

A scientist adds NaCl to water. What happens to the NaCl molecules?

Accepted Answer

NaCl dissociates into Na$$^+$$ and Cl$$^-$$ ions due to the polar nature of water.

Question 13

Which of the following is NOT a function of carbohydrates in cells?

Accepted Answer

Catalyzing chemical reactions

Question 14

Which statement about ATP (adenosine triphosphate) is correct?

Accepted Answer

ATP releases energy when its phosphate bonds are broken.

Question 15

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

Accepted Answer

They release energy as chemical bonds are broken in larger molecules.

Question 16

Which of the following is true about nucleic acids?

Accepted Answer

RNA can act as an enzyme and help form polypeptides.

Question 17

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

Accepted Answer

Waxes are completely insoluble in water.

Question 18

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

Accepted Answer

Nucleotides consist of a phosphate group, a pentose sugar, and a cyclic nitrogenous base.

Question 19

Which of the following best describes the difference between polar and nonpolar covalent bonds?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons, creating partial charges on atoms.

Ch.2 - The Chemistry of Microbiology: Atomic Structure and Elements Essential for Life

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