Question 1

Which property of carbon makes it uniquely suited to form the backbone of biological macromolecules?

Accepted Answer

Its valence of 4, allowing it to form four stable covalent bonds with other atoms

Question 2

A molecule of methane (CH$$_4) is $$shown in the images. What is the geometry of the methane molecule, and why?

Accepted Answer

Tetrahedral, because carbon forms four bonds directed toward the corners of a tetrahedron

Question 3

Which of the following best explains why visible light does not break the covalent bonds in organic molecules, but ultraviolet (UV) light can?

Accepted Answer

The energy of visible light is lower than the bond energy of C—C and C—H bonds, while UV light has enough energy to break these bonds

Question 4

Which functional group is most likely to confer a negative charge to a biological molecule at physiological pH?

Accepted Answer

Carboxyl group ($$-\mathrm{COO}^-)$$

Question 5

Which of the following statements about water is FALSE?

Accepted Answer

Water is a universal solvent because it is nonpolar

Question 6

A patient is suffering from heat stroke. Which property of water is most relevant to the use of water as a cooling agent in this scenario?

Accepted Answer

High heat of vaporization

Question 7

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer without the aid of a protein?

Accepted Answer

O$$_2$$

Question 8

Which statement best describes the amphipathic nature of phospholipids?

Accepted Answer

They have both hydrophilic heads and hydrophobic tails

Question 9

A protein is denatured by heating but regains its function when cooled. What does this demonstrate about protein structure?

Accepted Answer

The native conformation can be restored if the primary structure remains intact

Question 10

Which of the following best explains why only certain molecules can pass freely through the cell membrane?

Accepted Answer

The hydrophobic interior of the lipid bilayer prevents passage of most polar molecules

Question 11

Which of the following is a correct statement about the synthesis of macromolecules?

Accepted Answer

Polymers are synthesized by condensation (dehydration) reactions, which release water

Question 12

How many stereoisomers are possible for a molecule with 3 asymmetric carbon atoms?

Accepted Answer

$$2^3 = 8$

Question 13

Which of the following best describes the role of molecular chaperones in protein folding?

Accepted Answer

They prevent incorrect folding by binding to exposed regions during assembly

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 hydrocarbons are not soluble in water?

Accepted Answer

They are nonpolar and cannot interact favorably with polar water molecules

Question 16

Which of the following is a real-life example of the importance of selective permeability in biological membranes?

Accepted Answer

The ability of red blood cells to maintain ion gradients necessary for nerve impulse transmission

Question 17

Which of the following is true about the hierarchical assembly of cellular structures?

Accepted Answer

It allows for chemical simplicity, efficiency, and quality control during assembly

Question 18

Which of the following bonds is the strongest under physiological conditions?

Accepted Answer

Covalent bond

Question 19

Which of the following statements about the self-assembly of biological structures is correct?

Accepted Answer

Some structures, like ribosomes and membranes, can self-assemble without external guidance

CH 2 - The Chemistry of the Cell: Principles and Molecular Foundations

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