Question 1

Which property of water allows it to move upward through the xylem of plants against gravity, and what combination of forces is primarily responsible for this phenomenon?

Accepted Answer

Capillary action; due to the combined effects of cohesion, adhesion, and surface tension

Question 2

Why does ice float on liquid water, and what is the biological significance of this property?

Accepted Answer

Hydrogen bonds in ice form a crystalline structure that makes ice less dense than liquid water, insulating aquatic environments

Question 3

A student adds potassium chloride (KCl) to water. What happens at the molecular level?

Accepted Answer

K+ ions are surrounded by the partially negative oxygen atoms of water, and Cl- ions are surrounded by the partially positive hydrogen atoms

Question 4

Which property of water is most responsible for moderating Earth's climate and stabilizing temperatures in lakes and ponds?

Accepted Answer

High heat of vaporization

Question 5

What would be a likely environmental consequence if ice were more dense than liquid water?

Accepted Answer

Ice would sink, causing bodies of water to freeze from the bottom up and threatening aquatic ecosystems

Question 6

Which equation correctly represents the dissociation of water into ions?

Accepted Answer

$$\mathrm{H}_2\mathrm{O} \rightarrow \mathrm{H}^+ + \mathrm{OH}^-$$

Question 7

Why is water considered a 'universal solvent' in biological systems?

Accepted Answer

Its polarity allows it to dissolve many ionic and polar substances by forming hydrogen bonds

Question 8

Which property of water allows humans to cool down when they sweat?

Accepted Answer

Evaporative cooling due to high heat of vaporization

Question 9

A solution resists changes in pH when small amounts of acid or base are added. What is this solution called, and why is it important in biological systems?

Accepted Answer

A buffer; it helps maintain pH stability necessary for enzyme function

Question 10

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

Accepted Answer

Hydrogen bonds between water molecules require significant energy to break, so water resists temperature changes

Question 11

Which of the following scenarios demonstrates the property of adhesion?

Accepted Answer

Water climbing up a paper towel dipped in a glass of water

Question 12

Which of the following is a direct result of water's surface tension?

Accepted Answer

The formation of droplets and the ability of small insects to walk on water

Question 13

Which of the following best describes the interaction between water and glucose in solution?

Accepted Answer

Water forms hydrogen bonds with the oxygen and hydrogen atoms in glucose, allowing it to dissolve

Question 14

Which of the following best describes the role of the bicarbonate buffer system in human blood?

Accepted Answer

It resists changes in blood pH by shifting the equilibrium between $$\mathrm{CO}_2$$, $$\mathrm{H}_2\mathrm{CO}_3$$, $$\mathrm{H}^+$$, and $$\mathrm{HCO}_3^-$$

Question 15

Which of the following is NOT a consequence of water's polarity?

Accepted Answer

Low boiling point

Question 16

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

Accepted Answer

Water molecules surround Na+ and Cl- ions due to their polarity, separating and dissolving them

Question 17

Which property of water is most important for maintaining stable temperatures in organisms and environments?

Accepted Answer

High specific heat

Question 18

Which of the following is an example of water acting as a buffer in a biological system?

Accepted Answer

Water maintaining blood pH by participating in the bicarbonate buffer system

Question 19

Which of the following best describes why water is able to transport nutrients and waste in living organisms?

Accepted Answer

Water's polarity allows it to dissolve and carry a wide variety of substances

Question 20

Which property of water is responsible for the formation of menisci in graduated cylinders and the movement of water up thin tubes?

Accepted Answer

Adhesion

Properties of Water: Biological Importance and Mechanisms

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