Q: A solution has a pH of $$4. If $$lemon juice (an acid) is added, what will happen to the pH and the $$\text{H}^+$$ concentration?

The pH will decrease and the $$\text{H}^+$$ concentration will increase.

Q: Which of the following best describes the role of buffers in biological systems?

Buffers minimize changes in pH by absorbing or releasing $$\text{H}^+$$ ions as needed.

Question 1

Which of the following best describes the relationship between the genome and the proteome in a eukaryotic cell?

Accepted Answer

The genome stores genetic information, while the proteome consists of all proteins that carry out cellular functions.

Question 2

A scientist discovers a single-celled organism that lacks a membrane-bound nucleus and organelles. Which domain does this organism most likely belong to?

Accepted Answer

Bacteria or Archaea

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 4

A neutral atom of sodium ($$	ext{Na}) $$has an atomic number of $$11$$ and a mass number of $$23. $$How many neutrons does it have?

Accepted Answer

$$12$$

Question 5

Which of the following best explains why noble gases such as helium are chemically inert?

Accepted Answer

Their outermost electron shell is completely filled, making them stable and unreactive.

Question 6

Which type of bond is responsible for holding together the sodium and chloride ions in table salt ($$	ext{NaCl}$$)?

Accepted Answer

Ionic bond

Question 7

A solution has a pH of $$4. If $$lemon juice (an acid) is added, what will happen to the pH and the $$	ext{H}^+$$ concentration?

Accepted Answer

The pH will decrease and the $$	ext{H}^+$$ concentration will increase.

Question 8

Which functional group is responsible for making amino acids basic and able to accept a proton ($$	ext{H}^+$$)?

Accepted Answer

$$-	ext{NH}_2 ($$Amino group)

Question 9

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by absorbing or releasing $$	ext{H}^+$$ ions as needed.

Question 10

A hydrocarbon molecule is composed only of carbon and hydrogen atoms. Which of the following statements about hydrocarbons is correct?

Accepted Answer

Hydrocarbons are nonpolar and have high potential energy.

Question 11

Which of the following best explains why water molecules can form hydrogen bonds with each other?

Accepted Answer

Water molecules are polar, with partial positive and negative charges that attract each other.

Question 12

A DNA sample is found to contain $$30\%$$ adenine ($$A). $$According to Chargaff’s rules, what percentage of guanine ($$G) is $$present in the sample?

Accepted Answer

$$20\%$$

Question 13

Which of the following scenarios best illustrates the concept of dehydration synthesis?

Accepted Answer

Two monosaccharides join to form a disaccharide, releasing a molecule of water.

Question 14

Which of the following best describes an amphipathic molecule in an aqueous environment?

Accepted Answer

Its hydrophobic regions face inward, while hydrophilic regions face outward toward water.

Question 15

Which of the following is the correct order of the taxonomic hierarchy from most inclusive to least inclusive?

Accepted Answer

Domain $$\rightarrow$$ Kingdom $$\rightarrow$$ Phylum $$\rightarrow$$ Class $$\rightarrow$$ Order $$\rightarrow$$ Family $$\rightarrow$$ Genus $$\rightarrow$$ Species

Question 16

Which of the following best explains why carbon can form such a diversity of organic molecules?

Accepted Answer

Carbon has four valence electrons, allowing it to form up to four covalent bonds with other atoms.

Question 17

A molecule with the formula $$	ext{C}_6	ext{H}_{12}	ext{O}_6$$ can exist as glucose or fructose. These molecules are best described as:

Accepted Answer

Isomers

Question 18

Which of the following is a correct example of binomial nomenclature?

Accepted Answer

Homo sapiens

Question 19

Which of the following best describes the main finding of Rutherford’s gold foil experiment?

Accepted Answer

Most alpha particles passed straight through the foil, indicating that atoms are mostly empty space with a small, dense nucleus.

Question 20

Which of the following best describes the difference between discovery-based science and hypothesis testing?

Accepted Answer

Discovery-based science involves collecting data without a predefined hypothesis, while hypothesis testing involves formulating and testing a specific explanation.

Essential Chemistry and Biological Molecules for Introductory Biology

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