Question 1

Which of the following statements best explains why water is considered a 'universal solvent' in biological systems?

Accepted Answer

Water molecules are polar, allowing them to surround and dissolve many ionic and polar substances.

Question 2

A scientist is studying a molecule that has a region with a partial positive charge and another region with a partial negative charge. What type of bond is most likely responsible for this property?

Accepted Answer

Polar covalent bond

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 4

If a solution has a hydrogen ion concentration of $$1 	imes 10$$^{-4}$$ M, what is its pH?

Accepted Answer

$$pH = 4$$

Question 5

Which property of water allows it to help moderate Earth's climate by absorbing and releasing large amounts of heat with only slight changes in its own temperature?

Accepted Answer

High specific heat

Question 6

A molecule of sodium chloride (NaCl) dissolves in water. Which of the following best explains why this occurs?

Accepted Answer

Water's polarity allows it to surround and separate the Na$$^+$$ and Cl$$^-$$ ions.

Question 7

Which of the following best describes a buffer in a biological system?

Accepted Answer

A substance that prevents large sudden changes in pH by accepting or donating H$$^+$$ ions.

Question 8

Which of the following is true regarding the relationship between pH and hydrogen ion concentration?

Accepted Answer

A change of one pH unit represents a tenfold change in hydrogen ion concentration.

Question 9

A molecule contains a carbon atom double-bonded to an oxygen atom and single-bonded to two hydrogen atoms. Which type of bond is present between the carbon and oxygen?

Accepted Answer

Double covalent bond

Question 10

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

Accepted Answer

Hydrogen bonds in ice cause water molecules to be spaced farther apart, making ice less dense.

Question 11

A solution is found to have a pH of 3. Which of the following statements is correct?

Accepted Answer

The solution is acidic and has a high concentration of H$$^+$$ ions.

Question 12

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

A bond in which electrons are shared equally between atoms.

Question 13

Which of the following is a real-life example of the importance of hydrogen bonding in biology?

Accepted Answer

The high boiling point of water compared to similar-sized molecules

Question 14

A beaker contains 1 liter of solution with 0.5 moles of glucose. What is the molarity of the solution?

Accepted Answer

$$0.5 M$$

Question 15

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound is made of two or more elements in a fixed ratio, while a mixture is composed of elements or compounds in variable ratios.

Question 16

Which of the following best explains why sweating cools the body?

Accepted Answer

Sweat absorbs heat as it evaporates due to water's high heat of vaporization.

Question 17

Which of the following is true about ions?

Accepted Answer

An ion is an atom or molecule with a net electrical charge due to the loss or gain of electrons.

Question 18

A molecule of ammonia (NH$$_3) $$forms hydrogen bonds with water. Which property of ammonia allows this interaction?

Accepted Answer

Ammonia contains hydrogen atoms bonded to a highly electronegative atom (nitrogen), making it polar.

Question 19

Which of the following best describes surface tension in water?

Accepted Answer

It is the result of hydrogen bonds at the surface, making water molecules stick together and resist external force.

Atoms, Molecules, and Life: Foundations of General Biology

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