Question 1

Which of the following statements best explains why water is an efficient solvent for biological reactions?

Accepted Answer

Water's bent shape and highly polar covalent bonds allow it to form hydrogen bonds with charged and polar molecules.

Question 2

A molecule of carbon dioxide ($$CO_2) is $$described as having a linear geometry. What is the main reason for this shape?

Accepted Answer

The carbon atom forms two double bonds with oxygen atoms, and there are no unshared electron pairs on the central atom.

Question 3

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

Accepted Answer

In a polar covalent bond, electrons are shared unequally due to differences in electronegativity; in a nonpolar covalent bond, electrons are shared equally.

Question 4

Which property of water allows ice to float on liquid water, and why is this important for aquatic life?

Accepted Answer

Water forms an open crystal structure when frozen, making ice less dense than liquid water and allowing it to float, which insulates aquatic environments.

Question 5

A scientist adds hydrochloric acid ($$HCl) to a $$solution, causing the pH to drop from 7 to 3. What has happened to the concentration of hydrogen ions ($$[H^+]) in $$the solution?

Accepted Answer

The concentration of hydrogen ions has increased by a factor of $$10^4.$$

Question 6

Which functional group is most likely to act as a base by attracting a proton in aqueous solution?

Accepted Answer

Amino group ($$-NH_2$)

Question 7

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

Accepted Answer

Buffers minimize changes in pH, helping organisms maintain homeostasis.

Question 8

Which statement about chemical evolution is supported by Stanley Miller's spark-discharge experiment?

Accepted Answer

Simple molecules with high free energy can be converted into complex organic compounds when exposed to kinetic energy.

Question 9

Which of the following molecules would be least likely to dissolve in water?

Accepted Answer

Octane ($$C_8H_{18})$$

Question 10

What is the main reason carbon is the backbone of organic molecules in living organisms?

Accepted Answer

Carbon can form four covalent bonds, allowing for a limitless array of molecular shapes and sizes.

Question 11

Which of the following best describes the process of polymerization in biological macromolecules?

Accepted Answer

Polymerization occurs via condensation (dehydration) reactions, which result in the loss of a water molecule when monomers are joined.

Question 12

Which of the following statements about the first law of thermodynamics is correct?

Accepted Answer

Energy is conserved; it can be transferred or transformed but not created or destroyed.

Question 13

A chemical reaction is considered spontaneous if:

Accepted Answer

The products have lower potential energy and/or increased entropy compared to the reactants.

Question 14

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

Accepted Answer

Extensive hydrogen bonding between water molecules requires a large amount of energy to increase their movement.

Question 15

Which of the following is a consequence of water's cohesion and surface tension in nature?

Accepted Answer

Water can move upward through plant vessels against gravity due to cohesion and adhesion.

Question 16

Which of the following best describes the difference between an ion and an isotope?

Accepted Answer

An ion has a different number of electrons, resulting in a charge; an isotope has a different number of neutrons, resulting in a different mass.

Question 17

Which of the following equations correctly represents the dissociation of water and the formation of hydronium and hydroxide ions?

Accepted Answer

$$2H_2O \rightleftharpoons H_3O^+ + OH^-$$

Question 18

Which of the following functional groups is most likely to form a disulfide bond, stabilizing the structure of proteins?

Accepted Answer

Sulfhydryl group ($$-SH)$$

Question 19

A solution has a pH of 9. Which of the following statements is true?

Accepted Answer

The solution is basic and has a low concentration of $$H^+$$ ions.

Water and Carbon: The Chemical Basis of Life (Chapter 2 Study Notes)

Guida di studio - Domande di pratica

Study guide - Flashcard