Question 1

Which property of carbon most directly contributes to its ability to form large, complex, and diverse molecules essential for life?

Accepted Answer

Its four valence electrons, allowing it to form up to four covalent bonds

Question 2

Stanley Miller's classic experiment was significant because it demonstrated which of the following?

Accepted Answer

The abiotic synthesis of organic compounds under conditions thought to resemble those of early Earth

Question 3

Which of the following best explains why the overall percentages of major elements (C, H, O, N, S, P) are quite uniform from one organism to another?

Accepted Answer

These elements form the basic building blocks of biological macromolecules

Question 4

Which of the following is NOT a reason why hydrocarbons are important in biological systems?

Accepted Answer

They are highly soluble in water due to their hydrophilic nature

Question 5

Which type of isomer is most likely to have different biological activity, such as one form being an effective drug and the other being inactive or harmful?

Accepted Answer

Enantiomers

Question 6

A molecule with the formula $$C_5H_{12}$$ can exist as both pentane and 2-methylbutane. What type of isomerism does this illustrate?

Accepted Answer

Structural isomerism

Question 7

Which functional group is responsible for the acidic properties of organic acids, such as acetic acid?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 8

Which functional group is found in all amino acids and acts as a base by accepting $$H^+$$ ions?

Accepted Answer

Amino group ($$-NH_2$)

Question 9

Which functional group is most likely to form a cross-link that stabilizes protein structure?

Accepted Answer

Sulfhydryl group ($$-SH)$$

Question 10

ATP (adenosine triphosphate) is an important molecule in cells because it:

Accepted Answer

Stores and transfers energy through its phosphate groups

Question 11

Which of the following best describes the difference between ketone and aldehyde functional groups?

Accepted Answer

A ketone has a $$\u003eC=O$$ group within the carbon skeleton, while an aldehyde has a $$-CHO$$ group at the end of the skeleton

Question 12

Which functional group is most likely to confer a negative charge to a molecule and participate in energy transfer reactions?

Accepted Answer

Phosphate group ($$-PO_4$)

Question 13

Which of the following statements about enantiomers is TRUE?

Accepted Answer

Enantiomers are mirror images of each other and often have different biological activities

Question 14

Which functional group is LEAST likely to increase the solubility of an organic compound in water?

Accepted Answer

Methyl group ($$-CH_3$)

Question 15

A molecule contains both a carboxyl group and an amino group. What type of molecule is this most likely to be?

Accepted Answer

An amino acid

Question 16

Which of the following is a correct statement about the methyl group ($$-CH_3$)?

Accepted Answer

It is hydrophobic and often affects gene expression when added to DNA

Question 17

Which of the following molecules is an example of a hydrocarbon?

Accepted Answer

C$$_2H$_6$$

Question 18

Which of the following best explains why only one enantiomer of a drug is usually biologically active?

Accepted Answer

Organisms are sensitive to even subtle variations in molecular structure

Question 19

Which of the following functional groups is found in both estradiol and testosterone, and is responsible for their classification as steroids?

Accepted Answer

A four-ring carbon skeleton

Question 20

Which of the following best describes the process by which ATP releases energy for cellular work?

Accepted Answer

ATP is hydrolyzed to ADP and inorganic phosphate, releasing energy

Carbon and the Molecular Diversity of Life

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