Q: A solution has a pH of 3. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

$$[H^+] = 1 \times 10$$^{-3}$$\ \mathrm{M}$$

Q: A solution has a pH of 8. What is the concentration of $$[OH^-] in $$this solution?

$$[OH^-] = 1 \times 10$$^{-6}$$\ \mathrm{M}$$

Question 1

Which of the following best describes why water is able to moderate temperature so effectively in living organisms?

Accepted Answer

Water has a high specific heat due to hydrogen bonding, which means a large amount of energy is required to change its temperature.

Question 2

A solution has a pH of 3. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-3}$$\ \mathrm{M}$$

Question 3

Which property of water is most directly responsible for the ability of some insects to walk on water?

Accepted Answer

Surface tension resulting from hydrogen bonding between water molecules

Question 4

If the concentration of $$[OH^-] in a $$solution is $$1 	imes 10$$^{-10}$$\ \mathrm{M}$$, what is the pH of the solution?

Accepted Answer

pH = 4

Question 5

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

Accepted Answer

Hydrogen bonds in ice create a lattice structure that is less dense than liquid water.

Question 6

A buffer solution is important in biological systems because it:

Accepted Answer

Minimizes changes in pH by absorbing or donating $$H^+$$ ions.

Question 7

Which of the following statements about covalent bonds is correct?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity.

Question 8

A solution has a pH of 8. What is the concentration of $$[OH^-] in $$this solution?

Accepted Answer

$$[OH^-] = 1 	imes 10$$^{-6}$$\ \mathrm{M}$$

Question 9

Which of the following best describes the role of water as a solvent in biological systems?

Accepted Answer

Water's polarity allows it to dissolve many ionic and polar substances by surrounding and separating their ions or molecules.

Question 10

Which of the following scenarios best illustrates the concept of evaporative cooling in living organisms?

Accepted Answer

A person sweats during exercise, and as the sweat evaporates, their skin cools down.

Question 11

Which of the following is a correct statement about the relationship between $$[H^+]$$ and pH?

Accepted Answer

As $$[H^+]$$ increases, pH decreases.

Question 12

A lake is covered with a layer of ice in winter. Which property of water is most important for the survival of aquatic life in this scenario?

Accepted Answer

Ice is less dense than liquid water, so it floats and insulates the water below.

Question 13

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

Accepted Answer

The positive and negative ions of NaCl are attracted to the partial charges of the polar water molecules.

Question 14

Which of the following is an example of a weak chemical bond important in biological systems?

Accepted Answer

Hydrogen bond

Question 15

If a solution has $$[H^+] = 1 	imes 10$$^{-9}$$\ \mathrm{M}$$, what is its pH and is it acidic or basic?

Accepted Answer

pH = 9, basic

Question 16

Which of the following best describes the hierarchical organization of biological systems from smallest to largest?

Accepted Answer

Atoms $$\rightarrow$$ Molecules $$\rightarrow$$ Organelles $$\rightarrow$$ Cells $$\rightarrow$$ Tissues $$\rightarrow$$ Organs $$\rightarrow$$ Organisms

Question 17

Which of the following is true about the pH scale?

Accepted Answer

Each unit change in pH represents a tenfold change in $$[H^+]$$ concentration.

Question 18

Which of the following best explains why water is considered the 'solvent of life'?

Accepted Answer

Water's polarity allows it to dissolve a wide variety of substances necessary for biological processes.

Question 19

A patient’s blood pH drops from 7.4 to 7.1 due to a medical condition. Which of the following best describes the role of buffers in the blood in this scenario?

Accepted Answer

Buffers will absorb excess $$H^+$$ ions to minimize the change in pH.

Introduction to Biology and Water Chemistry: Foundations of Life

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