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

8

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 4

Radioactive isotopes are useful in medicine and research because:

Accepted Answer

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

Question 5

Which of the following is true for an atom with no net charge?

Accepted Answer

It has the same number of protons as electrons.

Question 6

If the atomic number of boron is 5, how many electrons does an uncharged boron atom have?

Accepted Answer

5

Question 7

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 8

What is the maximum number of covalent bonds a carbon atom can form?

Accepted Answer

4

Question 9

Which of the following molecules contains a polar covalent bond?

Accepted Answer

Water ($$H_2O)$$

Question 10

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

Accepted Answer

One more proton than electron.

Question 11

Which statement about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds are weak attractions between the partial positive charge of hydrogen and the partial negative charge of another atom.

Question 12

Which property of water allows plants to transport water against gravity?

Accepted Answer

Cohesion and adhesion

Question 13

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water due to the ordered arrangement of hydrogen bonds.

Question 14

Which of the following best describes a hydrophilic substance?

Accepted Answer

A substance that has an affinity for water and dissolves easily in it.

Question 15

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

Accepted Answer

The solution is acidic.

Question 16

Gastric juice has a pH of 2, while bile has a pH of 7. How many times greater is the $$[H^+]$$ concentration in gastric juice compared to bile?

Accepted Answer

$$10^5$$ times greater

Question 17

If human urine has a pH of 6 and household bleach has a pH of 12, the $$[H^+]$$ concentration in urine is:

Accepted Answer

$$10^6$$ times higher than in bleach

Question 18

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

Accepted Answer

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

Question 19

In the carbonic acid-bicarbonate buffer system, if the solution becomes too acidic, which direction does the reaction shift?

Accepted Answer

To the left: $$HCO_3^- + H$$^+ \rightarrow H_2CO_3$$

The Chemical Basis of Life: Study Notes for General Biology

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