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

Question 1

Which property of water is primarily responsible for the ability of some insects to walk on its surface?

Accepted Answer

Surface tension

Question 2

Which of the following best explains why water has a high heat of vaporization?

Accepted Answer

Hydrogen bonds between water molecules require significant energy to break.

Question 3

A scientist is studying a molecule that contains a carbon atom double-bonded to an oxygen atom. Which functional group is present?

Accepted Answer

Carbonyl group

Question 4

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

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

Question 5

Which of the following best describes the relationship between dehydration synthesis and hydrolysis?

Accepted Answer

Dehydration synthesis removes water to form bonds between monomers, while hydrolysis adds water to break those bonds.

Question 6

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

Accepted Answer

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

Question 7

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Hydrogen bonds in ice create a lattice that is less dense than liquid water.

Question 8

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

Accepted Answer

DNA is a double helix formed by two antiparallel strands held together by hydrogen bonds between complementary bases.

Question 9

A patient is experiencing acidosis (low blood pH). Which buffer system in the blood helps to maintain pH homeostasis?

Accepted Answer

Bicarbonate buffer system

Question 10

Which of the following best describes the difference between a saturated and an unsaturated fatty acid?

Accepted Answer

Unsaturated fatty acids have one or more double bonds in the hydrocarbon chain, causing kinks.

Question 11

Which of the following best explains the biological significance of the cohesiveness of water?

Accepted Answer

It allows water to be pulled upward through plant vessels against gravity.

Question 12

Which of the following is a correct pairing of a functional group and its property?

Accepted Answer

Carboxyl group: acidic

Question 13

A protein is exposed to high heat and loses its three-dimensional structure. What is this process called?

Accepted Answer

Denaturation

Question 14

Which of the following best describes the difference between a polypeptide and a protein?

Accepted Answer

A protein is a folded, functional form of one or more polypeptides.

Question 15

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

Accepted Answer

A solution with pH 7 is neutral because $$[H^+] = [OH^-].$$

Question 16

Which of the following best explains why carbon is able to form such a diversity of organic molecules?

Accepted Answer

Carbon can form up to four covalent bonds, allowing for a variety of skeletons and functional groups.

Question 17

Which of the following is a correct description of a peptide bond?

Accepted Answer

A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another.

Question 18

Which of the following best describes the role of the hydration shell in biological systems?

Accepted Answer

It surrounds ions and polar molecules, helping them remain dissolved in aqueous solutions.

Question 19

Which of the following statements about nucleotides is correct?

Accepted Answer

A nucleotide consists of a phosphate group, a pentose sugar, and a nitrogenous base.

Question 20

A biologist is comparing the structures of cellulose and starch. Which of the following statements is correct?

Accepted Answer

Both cellulose and starch are composed of glucose monomers, but cellulose has $$\beta-1$$,4 linkages while starch has $$\alpha-1$$,4 linkages.

The Chemical Context of Life: Biological Molecules and Their Properties

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