$$\text{Valence} = 3$$, forms 3 covalent bonds

Question 1

Which property of carbon allows it to form a large variety of complex molecules essential for life?

Accepted Answer

It has four valence electrons, allowing it to form up to four covalent bonds.

Question 2

Which of the following best describes a hydrocarbon?

Accepted Answer

A molecule containing only carbon and hydrogen atoms.

Question 3

What is the valence of nitrogen, and how many covalent bonds can it form?

Accepted Answer

$$	ext{Valence} = 3$$, forms 3 covalent bonds

Question 4

Which functional group is responsible for the acidic properties of acetic acid?

Accepted Answer

Carboxyl group ($$-\mathrm{COOH})$$

Question 5

Which type of isomerism is illustrated by cis-2-butene and trans-2-butene?

Accepted Answer

Cis-trans isomerism

Question 6

A pharmaceutical company discovers that only one enantiomer of a drug is effective. What is the most likely explanation?

Accepted Answer

Organisms are sensitive to subtle differences in molecular shape, so only one enantiomer fits the biological target.

Question 7

Which functional group is commonly involved in energy transfer within cells, such as in ATP?

Accepted Answer

Phosphate group

Question 8

What is the general formula for a carboxyl group?

Accepted Answer

$$-\mathrm{COOH}$$

Question 9

Which of the following best explains why fats are hydrophobic?

Accepted Answer

They contain many carbon-hydrogen bonds, which are nonpolar.

Question 10

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

Accepted Answer

Pentane and 2-methylbutane

Question 11

What is the main function of the methyl group ($$-\mathrm{CH}_3) in $$biological molecules?

Accepted Answer

It affects the expression of genes and the function of sex hormones.

Question 12

Which of the following best describes the reaction that releases energy from ATP?

Accepted Answer

ATP reacts with water, breaking a phosphate bond and releasing energy.

Question 13

Which functional group is found in all amino acids and acts as a base?

Accepted Answer

Amino group ($$-\mathrm{NH}_2)$$

Question 14

Which of the following is true about enantiomers?

Accepted Answer

They have the same molecular formula and are mirror images of each other.

Question 15

A molecule with the formula $$C_2H_6O$$ can be either ethanol or dimethyl ether. What type of isomerism does this illustrate?

Accepted Answer

Structural isomerism

Question 16

Which functional group can form a 'cross-link' that stabilizes protein structure?

Accepted Answer

Sulfhydryl group ($$-\mathrm{SH})$$

Question 17

Which of the following best explains why carbon is considered the backbone of life?

Accepted Answer

It can form four covalent bonds, allowing for a diversity of stable, complex molecules.

Question 18

Which functional group is most likely to be found in a molecule that acts as a base in aqueous solution?

Accepted Answer

Amino group

Question 19

Which of the following best describes the role of phospholipids in cell membranes?

Accepted Answer

They form a bilayer with hydrophilic heads and hydrophobic tails, separating the inside and outside of the cell.

Question 20

Which type of chemical bond joins a functional group to the carbon skeleton of a large molecule?

Accepted Answer

Covalent bond

Chapter 4: Carbon and the Molecular Diversity of Life – Study Notes

Study Guide - Practice Questions