Chapter 5 - Carbon

Question 1

Why is carbon called tetravalent?

Answer 1

It can form 4 covalent bonds (single, double, or triple).

Question 2

What is catenation?

Answer 2

Carbon’s ability to form chains or rings with itself.

Question 3

Why is carbon versatile?

Answer 3

It bonds with H, O, N, S, and P → supports life’s diversity.

Question 4

What biomolecules use carbon as a backbone?

Answer 4

Proteins, DNA, carbohydrates, lipids.

Question 5

What bonds does methane (CH₄) have?

Answer 5

4 single bonds

Question 6

What bonds does ethylene (C₂H₄) have?

Answer 6

A double bond.

Question 7

What bonds does acetylene (C₂H₂) have?

Answer 7

A triple bond.

Question 8

What are hydrocarbons?

Answer 8

Molecules made only of carbon and hydrogen.

Question 9

What are hydrocarbon functions in biology?

Answer 9

Energy storage, membrane structure, protein folding.

Question 10

What are alkanes?

Answer 10

Single bonds, formula CₙH₂ₙ₊₂, saturated, less reactive (e.g., methane, ethane).

Question 11

What are alkenes?

Answer 11

Double bonds, formula CₙH₂ₙ, unsaturated, reactive (e.g., ethene, propene).

Question 12

What are alkynes?

Answer 12

Triple bonds, formula CₙH₂ₙ₋₂, linear, highly reactive (e.g., ethyne, propyne)

Question 13

What are aromatic hydrocarbons?

Answer 13

Benzene-ring based (C₆H₆), resonance-stable, planar (e.g., benzene, toluene).

Question 14

How do hydrocarbons help in cell membranes?

Answer 14

Lipid tails form hydrophobic barriers.

Question 15

How do hydrocarbons store energy?

Answer 15

Fats and oils have long hydrocarbon chains.

Question 16

How do hydrocarbons affect proteins?

Answer 16

Hydrophobic interiors shape protein folding.

Question 17

What materials do hydrocarbons provide?

Answer 17

Precursors for vitamins, steroids, and hormones.

Question 18

What is the hydroxyl group and its role?

Answer 18

–OH; polar, hydrogen bonding, water-soluble (alcohols, sugars).

Question 19

What is the carbonyl group and its role?

Answer 19

C=O; polar, reactive, sugar structure/metabolism (glucose, ketones).

Question 20

What is the carboxyl group and its role?

Answer 20

–COOH; acidic, forms H⁺, hydrogen/ionic bonding (fatty acids, amino acids).

Question 21

What is the amino group and its role?

Answer 21

–NH₂; basic, hydrogen bonding, forms proteins (amino acids).

Question 22

What is the sulfhydryl group and its role?

Answer 22

–SH; forms disulfide bonds for protein folding (cysteine).

Question 23

What is the phosphate group and its role?

Answer 23

–PO₄²⁻; acidic, energy transfer, nucleic acids (ATP, DNA, RNA).

Question 24

What is the methyl group and its role?

Answer 24

–CH₃; nonpolar, gene expression, hydrophobic (methylated DNA, lipids).

Question 25

Why are functional groups important?

Answer 25

They determine polarity, solubility, and reactivity of molecules.

Question 26

How do functional groups enable biomolecular functions?

Answer 26

They allow structure, energy transfer, and signaling.

Question 27

What is an example of groups combining?

Answer 27

NH₂ + –COOH → amino acids → proteins.

Question 28

What bond type do organic compounds usually have?

Answer 28

Mostly covalent.

Question 29

Are organic molecules large or small?

Answer 29

Large and complex.

Question 30

Give examples of organic vs inorganic compounds.

Answer 30

Organic: glucose, proteins, DNA. Inorganic: water, salts, acids.

Question 31

What are structural isomers?

Answer 31

Same formula, different structure (e.g., propan-1-ol vs propan-2-ol).

Question 32

What are geometric isomers?

Answer 32

Differ in arrangement around double bonds (cis-/trans-1,2-dichloroethene).

Question 33

What are enantiomers?

Answer 33

Mirror-image isomers, not superimposable (L- vs D-amino acids).

Question 34

Why do isomers matter?

Answer 34

Structure changes → property/function changes (e.g., life uses L-amino acids, D-forms often inactive).