Carbohydrates & lipids

Question 1

What are monomers and polymers?

Answer 1

Monomers: Smaller units from which larger molecules are made (e.g., monosaccharides, amino acids, nucleotides). Polymers: Molecules made from a large number of monomers joined together.

Question 2

What are the monomers of carbohydrates called?

Answer 2

Monosaccharides are the monomers of carbohydrates.

Question 3

What are three examples of common monosaccharides?

Answer 3

Glucose, galactose, and fructose.

Question 4

What is the general formula of a monosaccharide?

Answer 4

(CH2O)n, where n = 3-7.

Question 5

What is a disaccharide?

Answer 5

A pair of monosaccharides joined together.

Question 6

What are polysaccharides?

Answer 6

Many monosaccharides joined together.

Question 7

Why is carbon important for life?

Answer 7

Carbon atoms readily form bonds with other carbon atoms, creating large chains of carbon atoms to which other atoms can attach. This allows for a variety of molecules based on carbon.

Question 8

What is glucose classified as, and what is its formula?

Answer 8

Glucose is a hexose sugar (6-carbon sugar) with the formula C6H12O6.

Question 9

What are the two isomers of glucose?

Answer 9

Alpha-glucose and beta-glucose.

Question 10

How are disaccharides formed?

Answer 10

Two monosaccharides join by a condensation reaction, forming a glycosidic bond.

Question 11

How can glycosidic bonds in disaccharides be broken?

Answer 11

By adding water in a hydrolysis reaction.

Question 12

Name the products of glucose + glucose, glucose + fructose, and glucose + galactose.

Answer 12

Maltose, sucrose, and lactose, respectively.

Question 13

What is a polysaccharide, and how is it formed?

Answer 13

A polysaccharide is formed from many monosaccharides joined by glycosidic bonds through condensation reactions.

Question 14

Where is starch found, and what is its function?

Answer 14

Starch is found in plants and small grains. It functions as energy storage.

Question 15

How is glycogen different from starch?

Answer 15

Glycogen has shorter chains and is more highly branched than starch.

Question 16

Where is glycogen found, and what is its function?

Answer 16

Glycogen is found in animals and bacteria (liver and muscle) and functions as energy storage.

Question 17

What is cellulose made of, and what is its role?

Answer 17

Cellulose is made of beta-glucose with straight, unbranched chains. It provides rigidity to plant cell walls by forming hydrogen bonds between chains.

Question 18

Why is starch a good storage molecule?

Answer 18

Starch is insoluble (does not affect water potential), compact (stored in a small space), and made of alpha-glucose for respiration.

Question 19

Why is glycogen suitable for energy storage in animals?

Answer 19

It can be hydrolyzed easily, is insoluble (does not affect water potential), and is compact for storage in small spaces.

Question 20

What makes cellulose strong and rigid?

Answer 20

Cellulose has many hydrogen bonds between parallel chains, providing strength and rigidity to plant cell walls.

Question 21

What are lipids classified as, and what are the two main types?

Answer 21

Lipids are classified as triglycerides/diglycerides. Types: Saturated (no double bonds) and unsaturated (at least one double bond).

Question 22

What are the uses of lipids in the body?

Answer 22

Protection (shock absorption), insulation, waterproofing, and energy storage.

Question 23

What is a triglyceride made of, and how is it formed?

Answer 23

A triglyceride is made of one glycerol and three fatty acids, formed by a condensation reaction that creates ester bonds.

Question 24

What are the differences between phospholipids and triglycerides?

Answer 24

Phospholipids have two fatty acids (not three), a phosphate head, and a hydrophobic/hydrophilic part.

Question 25

What is the difference between saturated, monounsaturated, and polyunsaturated fatty acids?

Answer 25

Saturated: no double bonds, solid at room temp. Monounsaturated: one double bond, liquid at room temp. Polyunsaturated: multiple double bonds, liquid at room temp.

Question 26

What are the structure and functions of lipids?

Answer 26

Structure: high energy density, small volume, insoluble in water. Functions: efficient energy storage, does not affect water potential, source of water when oxidized.

Question 27

What is the test for starch, and what are the results?

Answer 27

Reagent: iodine. Positive result: black/blue. Negative result: stays the same color.

Question 28

What is the test for reducing sugars, and what are the results?

Answer 28

Reagent: Benedict’s solution (heated in a water bath). Positive: blue to green/yellow/brick-red. Negative: remains blue.

Question 29

What is the test for lipids, and what are the results?

Answer 29

Reagent: ethanol. Positive: milky white emulsion. Negative: no change.

Question 30

What is the test for proteins, and what are the results?

Answer 30

Reagent: Biuret solution. Positive: blue to purple. Negative: remains blue.

Question 31

How do you test for non-reducing sugars?

Answer 31

Use HCl to break glycosidic bonds, neutralize with NaOH, then test with Benedict’s solution. Positive: as for reducing sugars.