Question 1

Which of the following statements best explains why biologists need to study chemistry?

Accepted Answer

Because all biological functions are determined by the arrangement and interactions of molecules, which are governed by chemical principles.

Question 2

An atom of carbon has an atomic number of 6 and a mass number of 14. How many neutrons does it have?

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons and therefore different mass numbers.

Question 4

Radioactive isotopes are useful in medicine and research because:

Accepted Answer

They can be easily detected and tracked as they move through biological systems.

Question 5

Which of the following statements about chemical bonds is correct?

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another, resulting in oppositely charged ions that attract each other.

Question 6

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

Accepted Answer

High surface tension due to hydrogen bonding between water molecules.

Question 7

A solution has a pH of 6. Which of the following is true?

Accepted Answer

The solution is acidic.

Question 8

If gastric juice has a pH of 2 and bile has a pH of 7, how many times greater is the $$[H^+]$$ concentration in gastric juice compared to bile?

Accepted Answer

$$10^{7-2}$$ = $$10^5$$ times greater

Question 9

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

Accepted Answer

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

Question 10

What happens to the carbonic acid-bicarbonate buffer system when the blood becomes too acidic?

Accepted Answer

The reaction shifts to the left: $$HCO_3^- + H$$^+ \rightarrow H_2CO_3$$

Question 11

Which of the following molecules is most likely to be hydrophobic?

Accepted Answer

A molecule composed mostly of nonpolar covalent bonds, such as a hydrocarbon.

Question 12

Which of the following statements about water is FALSE?

Accepted Answer

Water molecules are held together by hydrogen bonds within the molecule.

Question 13

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

Accepted Answer

Hydrogen bonds in ice create a more ordered structure, making ice less dense than liquid water.

Question 14

Which type of chemical bond is responsible for the unique properties of water, such as cohesion and high specific heat?

Accepted Answer

Hydrogen bonds between water molecules.

Question 15

A sodium ion ($$Na^+) $$has:

Accepted Answer

One more proton than electron.

Question 16

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between atoms, resulting in partial charges.

Question 17

Which of the following is a real-world example of the importance of trace elements in biology?

Accepted Answer

Iodine is required for thyroid hormone production; deficiency can lead to goiter.

Question 18

Which of the following best describes the relationship between pH and $$[H^+]$$ concentration?

Accepted Answer

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

Question 19

Which of the following is a multi-step application question: If human urine has a pH of 6 and household bleach has a pH of 12, how many times greater is the $$[H^+]$$ concentration in urine compared to bleach?

Accepted Answer

$$10^{12-6}$$ = $$10^6$$ times greater

The Chemical Basis of Life: Foundations for General Biology

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