Question 1

Which property of carbon most directly contributes to its ability to form a vast diversity of organic molecules essential for life?

Accepted Answer

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

Question 2

Stanley Miller's classic experiment in the 1950s demonstrated which of the following concepts about the origin of life?

Accepted Answer

Abiotic synthesis of organic molecules is possible under conditions thought to resemble those of early Earth.

Question 3

Which of the following best explains why hydrocarbons are a major component of fats and serve as an energy source in living organisms?

Accepted Answer

Hydrocarbons contain many nonpolar C-H bonds that store significant amounts of energy.

Question 4

Which of the following is an example of a structural isomer?

Accepted Answer

Two molecules with the same molecular formula but different covalent arrangements of their atoms.

Question 5

A pharmaceutical company is developing a new drug. Why must they consider the enantiomers of the drug molecule?

Accepted Answer

Only one enantiomer may be biologically active, while the other could be ineffective or harmful.

Question 6

Which functional group is responsible for the acidic properties of acetic acid, as found in vinegar?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 7

Which of the following best describes the role of ATP in cellular processes?

Accepted Answer

ATP stores potential energy in its phosphate bonds, which is released during hydrolysis to power cellular work.

Question 8

Which of the following molecules contains a carbonyl group?

Accepted Answer

Acetone ($$CH_3COCH_3)$$

Question 9

A molecule with the formula $$C_6H_{12}O_6$ can exist as both glucose and fructose. What type of isomerism does this illustrate?

Accepted Answer

Structural isomerism

Question 10

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

Accepted Answer

Sulfhydryl group ($$-SH)$$

Question 11

Which of the following statements about the versatility of carbon is correct?

Accepted Answer

Carbon's four valence electrons allow it to form single, double, or triple covalent bonds with a variety of atoms.

Question 12

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

Accepted Answer

Biological receptors are themselves chiral and can distinguish between different enantiomers.

Question 13

Which functional group is characteristic of alcohols and is found in ethanol?

Accepted Answer

Hydroxyl group ($$-OH)$$

Question 14

A molecule contains both an amino group and a carboxyl group. Which class of biological molecules does it most likely belong to?

Accepted Answer

Amino acids

Question 15

Which of the following best describes the difference between ketones and aldehydes?

Accepted Answer

Ketones have a carbonyl group within the carbon skeleton, while aldehydes have it at the end.

Question 16

Which functional group is responsible for transferring energy between organic molecules in cells, as seen in ATP?

Accepted Answer

Phosphate group ($$-$$OPO_3$$^{2-})$$

Question 17

Which of the following best explains why fats are hydrophobic?

Accepted Answer

They are composed largely of nonpolar hydrocarbon chains.

Question 18

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

Accepted Answer

It is nonpolar and can affect the expression of genes when attached to DNA.

Question 19

A molecule with the formula $$CO(NH_2$)_2 is $$known as urea. Which functional groups are present in urea?

Accepted Answer

Amino and carbonyl groups

Question 20

Which of the following best describes the relationship between estradiol and testosterone?

Accepted Answer

They are both steroids with the same carbon skeleton but differ in the functional groups attached.

Carbon and the Molecular Diversity of Life

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