Question 1

Which of the following best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water molecules are polar, allowing them to surround and interact with charged and polar solutes.

Question 2

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-4}$$ M. What is the pH of this solution?

Accepted Answer

$$4$$

Question 3

Which of the following statements about non-covalent interactions is CORRECT?

Accepted Answer

They are weak and reversible, allowing dynamic molecular interactions in cells.

Question 4

Which property of water allows aquatic organisms to survive under ice during winter?

Accepted Answer

Water is less dense as a solid than as a liquid.

Question 5

Which of the following functional groups is correctly matched with its property?

Accepted Answer

Amino group: charged, basic, accepts $$H^+$$

Question 6

A protein is exposed to high temperature and strong acid. Which levels of protein structure are most likely to be disrupted?

Accepted Answer

Secondary, tertiary, and quaternary structures

Question 7

Which of the following best describes the difference between a condensation (dehydration synthesis) and a hydrolysis reaction?

Accepted Answer

Condensation reactions release water as a byproduct when forming covalent bonds; hydrolysis reactions consume water to break covalent bonds.

Question 8

Which of the following statements about isomers is TRUE?

Accepted Answer

Isomers have the same molecular formula but different structures.

Question 9

A solution has a pH of 9. What is the hydrogen ion concentration $$[H^+] of $$this solution?

Accepted Answer

$$1 	imes 10$$^{-9}$$ M

Question 10

Which of the following best explains why saturated fatty acids tend to be solid at room temperature while unsaturated fatty acids are liquid?

Accepted Answer

Saturated fatty acids have straight chains that pack closely together, increasing melting point.

Question 11

Which of the following statements about amino acids is CORRECT?

Accepted Answer

Each amino acid contains at least two ionizable groups: an amino group and a carboxyl group.

Question 12

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers maintain a relatively constant pH by neutralizing added acids or bases.

Question 13

Which of the following is a correct statement about the structure of DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 14

Which of the following best explains why phospholipids form bilayers in aqueous environments?

Accepted Answer

Their fatty acid tails are hydrophobic and avoid water, while their phosphate heads are hydrophilic and interact with water.

Question 15

Which of the following is a property of the carboxyl group ($$-COOH) $$found in amino acids?

Accepted Answer

It is polar, soluble, and has acidic properties.

Question 16

Which of the following best describes the primary structure of a protein?

Accepted Answer

The sequence of amino acids in a polypeptide chain.

Question 17

Which of the following statements about hydrogen bonds is TRUE?

Accepted Answer

Hydrogen bonds form between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 18

Which of the following is a correct comparison between storage and structural polysaccharides?

Accepted Answer

Storage polysaccharides (e.g., starch, glycogen) are branched and easily hydrolyzed; structural polysaccharides (e.g., cellulose) are unbranched and form rigid structures.

Question 19

Which of the following best explains why a single amino acid change in a protein can affect its function?

Accepted Answer

The sequence of amino acids determines the protein's 3D structure, which is critical for its function.

Small Molecules and the Chemistry of Life: Foundations for Biological Macromolecules

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