Question 1

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

Accepted Answer

A polar covalent bond involves the unequal sharing of electrons due to a difference in electronegativity, while a nonpolar covalent bond involves the equal sharing of electrons.

Question 2

Given the electronegativity values: $$\mathrm{H} = 2.20$$, $$\mathrm{O} = 3.44$$, what type of bond is formed between hydrogen and oxygen in a water molecule?

Accepted Answer

Polar covalent bond

Question 3

Which property of water allows it to moderate Earth's climate and stabilize temperatures in organisms?

Accepted Answer

High specific heat

Question 4

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds form a crystalline lattice that spaces water molecules further apart.

Question 5

A solution has a hydrogen ion concentration of $$[\mathrm{H}^+] = 1 	imes 10$$^{-5}$$\ \mathrm{M}. $$What is the pH of this solution?

Accepted Answer

$$pH = 5$$

Question 6

Which of the following best explains why salt (NaCl) dissolves readily in water?

Accepted Answer

Water is polar and can stabilize the positive and negative ions formed when NaCl dissociates.

Question 7

Which functional group is responsible for the acidic properties of amino acids?

Accepted Answer

Carboxyl group ($$-\mathrm{COOH})$$

Question 8

A buffer solution is important in biological systems because it:

Accepted Answer

Minimizes changes in pH by accepting or donating hydrogen ions.

Question 9

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 10

If the pH of a solution changes from 7 to 5, what happens to the hydrogen ion concentration?

Accepted Answer

It increases by 100-fold.

Question 11

Which of the following best describes a hydrophobic molecule?

Accepted Answer

A molecule that repels water and does not dissolve in it.

Question 12

Which of the following is an example of an isomer?

Accepted Answer

Two molecules with the same molecular formula but different structures.

Question 13

Which of the following functional groups is found in ATP and is important for energy transfer in cells?

Accepted Answer

Phosphate group ($$-\mathrm{PO}_4$$^{2-}$$)

Question 14

A molecule with the formula $$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$$ can exist as glucose or fructose. What type of isomerism does this represent?

Accepted Answer

Structural isomerism

Question 15

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

Accepted Answer

Water is polar and can surround and stabilize both positive and negative ions.

Question 16

Which of the following statements about carbon is true and explains its central role in the diversity of organic molecules?

Accepted Answer

Carbon can form four covalent bonds, allowing for a variety of stable structures.

Question 17

A biologist adds ammonia ($$\mathrm{NH}_3) to $$water, resulting in the formation of ammonium ($$\mathrm{NH}_4^+) $$and hydroxide ($$\mathrm{OH}^-) $$ions. What effect does this have on the pH of the solution?

Accepted Answer

The pH increases, making the solution more basic.

Question 18

Which of the following best describes the role of functional groups in organic molecules?

Accepted Answer

They impart specific chemical properties and reactivity to the molecule.

Question 19

Which of the following scenarios best illustrates the concept of cohesion in water?

Accepted Answer

Water molecules forming droplets on a waxed car hood due to mutual attraction.

Question 20

A solution has a pH of 3. How does its hydrogen ion concentration compare to a solution with a pH of 6?

Accepted Answer

It is 1000 times higher.

Chemical Bonds, Water, pH, and Carbon in Biology

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드