Chemical Composition of Cells

Question 1

The oxygen molecule (O2) has what type of chemical bond?

A. Covalent
B. Ionic
C. Hydrogen
D. Metallic

Answer 1

A. Covalent

Question 2

One of the most important properties of water is its ability to form hydrogen bonds between individual water molecules. What is this property called?

A. Dissolution
B. Respiration
C. Adhesion
D. Cohesion

Answer 2

D. Cohesion

Question 3

The cell is primarily composed of water. Which type of hydrogen bond is formed by water?

A. Covalent bonds between hydrogen atoms
B. Covalent bonds between hydrogen and oxygen atoms
C. Strong electrostatic bonds between positive hydrogen ions and negative oxygen ions
D. Non-covalent bonds between partially charged hydrogen and oxygen atoms

Answer 3

D. Non-covalent bonds between partially charged hydrogen and oxygen atoms

Question 4

What makes RNA less stable and more reactive than DNA?

A. DNA can only be double-stranded.
B. DNA has stronger bonds than RNA.
C. Proteins can bind RNA tighter than DNA.
D. RNA contains an extra hydroxyl group.

Answer 4

D. RNA contains an extra hydroxyl group.

Question 5

Why does an extra hydroxyl group in RNA make it less stable?

Answer 5

because it causes a more spontaneous reaction with the environment. Since the extra hydroxyl group is more reactive, it can also cause proteins to bind irreversibly, leading to DNA damage

Question 6

Why does rainwater have low salinity when the large bodies of water on Earth, such as seas and oceans, are very saline?

A. Most of the salt in the precipitates remains in the oceans.
B. Most of the salt in the precipitates remains in the clouds.
C. Most of the salt in the vapors is dissolved in the air.
D. Most of the salt in the vapors is converted to energy.

Answer 6

A. Most of the salt in the precipitates remains in the oceans.

Question 7

Sulfur has an atomic number of 16, and it can be paired with hydrogen using a covalent bond that results in hydrogen sulfide. Considering the number of valence electrons of sulfur, what formula is correct?

A. HS
B. HS2
C. H2S
D. H3S2

Answer 7

C. H2S

Question 8

Some animals regulate body temperature through perspiration. What property of water is associated with the ability to decrease body temperature?

A. There is a change in density when water condenses.
B. Water can dissolve molecules in the air.
C. Water can release heat by the formation of hydrogen bonds.
D. Water absorbs heat by breaking hydrogen bonds.

Answer 8

D. Water absorbs heat by breaking hydrogen bonds.

Question 9

Carbonic acid and sodium bicarbonate (sodium hydrogen carbonate) reactions in the body serve as a buffer system to regulate the acidity of the blood. When a small amount of acid is added, the H+ ions are used up as they combine with the bicarbonate ions. What is most likely to occur as a result?

A. the pH level of the blood increases
B. The pH level of the blood decreases
C. The reaction is irreversible
D. the pH of the blood does not change

Answer 9

D. the pH of the blood does not change