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

Question 1

Which property of water is primarily responsible for the ability of plants to transport water from their roots to their leaves against gravity?

Accepted Answer

Cohesion and adhesion

Question 2

Water has a high specific heat. What is the biological significance of this property for living organisms?

Accepted Answer

It helps maintain stable internal and environmental temperatures.

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

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

Question 5

Which of the following substances would most likely be hydrophobic?

Accepted Answer

Olive oil

Question 6

What is the main reason water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water molecules form hydration shells around ions due to their polarity.

Question 7

Which equation correctly represents the relationship between pH and hydrogen ion concentration?

Accepted Answer

$$pH = -\log[H^+]$$

Question 8

A buffer solution contains a weak acid and its corresponding base. What is the primary function of a buffer in biological systems?

Accepted Answer

To minimize changes in pH when acids or bases are added.

Question 9

Which of the following best describes the process of evaporative cooling?

Accepted Answer

Water molecules with the greatest kinetic energy leave as gas, cooling the surface.

Question 10

If the pH of a solution changes from 6 to 4, how does the hydrogen ion concentration change?

Accepted Answer

It increases by 100-fold.

Question 11

Which of the following is an example of a strong acid dissociating in water?

Accepted Answer

$$HCl + H_2O \rightarrow H^+ + Cl^-$$

Question 12

Which property of water allows insects to walk on its surface?

Accepted Answer

Surface tension due to cohesion

Question 13

A patient’s blood pH drops from 7.4 to 7.0. What role does the bicarbonate buffer system play in this scenario?

Accepted Answer

It accepts excess $$H^+$$ ions to minimize the pH change.

Question 14

Which of the following statements about acids and bases is correct?

Accepted Answer

A base reduces the $$H^+$$ concentration by accepting hydrogen ions.

Question 15

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between water molecules; adhesion is the attraction between water and other substances.

Question 16

Which of the following is true about the pH scale?

Accepted Answer

A solution with pH 6 has a higher $$[H^+]$$ than a solution with pH 8.

Question 17

Which of the following molecules would most likely dissolve in water?

Accepted Answer

A polar molecule like glucose

Question 18

Which process is responsible for the cooling effect when humans sweat?

Accepted Answer

Evaporative cooling

Question 19

What happens to the hydrogen bonds in water when heat is absorbed?

Accepted Answer

Hydrogen bonds break, absorbing heat.

Question 20

Which of the following best explains why the internal pH of most living cells is close to 7?

Accepted Answer

Buffers in cells minimize changes in $$[H^+]$$ and $$[OH^-].$$

Water and Life: Properties and Biological Importance

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