Question 1

Which property of carbon is most responsible for the diversity of organic molecules found in living organisms?

Accepted Answer

Its tetravalency, allowing it to form four covalent bonds with a variety of atoms

Question 2

Which of the following best explains why visible light does not break the covalent bonds in organic molecules?

Accepted Answer

Visible light has a longer wavelength and therefore less energy than the bond energy of C—C bonds

Question 3

Which of the following functional groups is correctly matched with its charge at physiological pH?

Accepted Answer

Phosphate group: negatively charged

Question 4

A molecule with the formula $$C_2H_4$$ contains what type of bond between the carbon atoms?

Accepted Answer

A double bond

Question 5

Which property of water is primarily responsible for its ability to moderate temperature changes in living organisms?

Accepted Answer

High specific heat

Question 6

Why are hydrocarbons generally insoluble in water?

Accepted Answer

They are nonpolar and cannot form hydrogen bonds with water

Question 7

Which of the following statements about the lipid bilayer of biological membranes is correct?

Accepted Answer

It is selectively permeable, allowing nonpolar molecules to pass more easily than polar molecules

Question 8

What is the main reason ions cannot freely diffuse across the lipid bilayer of cell membranes?

Accepted Answer

Ions are surrounded by a hydration shell and the hydrophobic interior of the membrane prevents their passage

Question 9

Which process describes the synthesis of macromolecules from monomers in cells?

Accepted Answer

Condensation (dehydration) reaction

Question 10

A protein is denatured by heat and then returned to normal conditions. What is most likely to happen?

Accepted Answer

It may refold into its native conformation and regain function, depending on the protein

Question 11

Which of the following best describes the role of molecular chaperones in cells?

Accepted Answer

They assist in the correct folding of proteins without being part of the final structure

Question 12

Which of the following is an example of a condensation reaction in biological systems?

Accepted Answer

Linking amino acids together to form a polypeptide, releasing water

Question 13

Which of the following statements about stereoisomers is correct?

Accepted Answer

A molecule with two asymmetric carbons will have $$2^2 = 4$ possible stereoisomers

Question 14

Which of the following is NOT a property of water that is critical for life?

Accepted Answer

Low specific heat

Question 15

Which of the following best explains why water is an excellent solvent for ionic compounds like NaCl?

Accepted Answer

Water forms hydration shells around ions due to its polarity, decreasing the chance of reassociation

Question 16

Which of the following is a correct statement about the assembly of biological macromolecules?

Accepted Answer

Monomers must be activated, often by coupling to a carrier molecule, before polymerization

Question 17

Which of the following interactions is the strongest in stabilizing the three-dimensional structure of a protein?

Accepted Answer

Covalent bonds (such as disulfide bridges)

Question 18

Which of the following best describes the amphipathic nature of membrane phospholipids?

Accepted Answer

They have both a hydrophilic head and two hydrophobic tails

Question 19

Which of the following is a real-world example of the importance of water's high heat of vaporization?

Accepted Answer

Evaporative cooling in humans through sweating

Question 20

Which of the following statements about hierarchical assembly in cells is correct?

Accepted Answer

It allows for quality control by discarding defective components before higher-level assembly

Chapter 2: The Chemistry of the Cell – Study Notes

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