Carbohydrates

Question 1

What are all carbohydrates composed of?

Answer 1

Consists of single units called monosaccharides containing only carbon, hydrogen and oxygen.

Question 2

Differentiate between the different types of saccharides.

Answer 2

Monosaccharide=single sugar unit
Disaccharide=2 sugar units
Polysaccharides=3 or more sugar units

Question 3

What is the general formula for monosaccharides?

Answer 3

(CH2O)n

Question 4

Name 2 isomers of glucose.

Answer 4

Alpha and beta glucose

Question 5

Name the monosaccharides in lactose.

Answer 5

B glucose and galactose

Question 6

What is the source of lactose?

Answer 6

Main carb in milk

Question 7

Name the monosaccharides of maltose

Answer 7

Glucose and glucose

Question 8

Where might hydrolysis take place?

Answer 8

During digestion in the gut and in muscle and liver cells when carbs are broken down during respiration

Question 9

What are the 3 main types of polysaccharides?

Answer 9

Starch, glycogen and cellulose

Question 10

What is starch used for?

Answer 10

Energy storage in plants

Question 11

What compounds of A glucose make up starch?

Answer 11

Amylose and amylopectin

Question 12

Describe the structure of amylose.

Answer 12

Long, unbranched chains of α-glucose
Angles of glycosidic bonds makes it a coiled structure, this makes it compact and good for storage. Amylose is insoluble so does not effect water potential, contain 1-4 glycosidic bonds

Question 13

Describe the structure of amylopectin?

Answer 13

Long, branched chains of α-glucose. Has side branches which allows enzyme to hydrolyse bonds more easily so glucose is released quickly, amylopectin is insoluble so does not effect water potential inside a cell, contain 1-4 glyosidic bonds and branches with 1-6 glycosidic bonds

Question 14

What are the roles of amylose and amylopectin in starch?

Answer 14

Amylose releases glucose slowly over a longer period of time keeping you going longer. Amylopectin releases glucose rapidly for cellular respiration

Question 15

What is glycogen used for?

Answer 15

Only carbohydrate energy store in animals

Question 16

How does glycogen differ from starch?

Answer 16

Glycogen molecule has more 1,6 glycosidic bonds giving it many more side branches, meaning it can be broken down more rapidly

Question 17

Why is glycogen branched?

Answer 17

The branched structure means that it can be used as a source of glucose for active tissues with a constantly high rate of cellular respiration such as muscle and liver tissue

Question 18

What is cellulose made of?

Answer 18

Long unbranched chains of B glucose

Question 19

Why can humans not digest cellulose?

Answer 19

We lack the enzyme needed to break the 1,4 glycosidic bonds between B glucose

Question 20

How does Beta glucose differ from Alpha glucose?

Answer 20

One of the -OH swaps with the H.

Question 21

The internal conditions within the body are maintained by homeostatic mechanisms. The
regulation of blood glucose involves homeostatic mechanisms. (i) Describe how glucose moves into cells by facilitated diffusion

Answer 21

• Carrier protein in cell surface membrane
• Glucose moves from high to low conc
• Glucose binds to carrier protein and protein changes shape

Question 22

Explain how the structure of glycogen allows it to be an energy store

Answer 22

• Glycogen is a polymer of glucose
• Provides glucose for respiration
• Contains 1,6 glycosidic bonds for rapid hydrolysis

Question 23

Describe the reaction that joins two α-glucose molecules to form a disaccharide

Answer 23

• Condensation reaction involving -OH groups on either side

Question 24

Carbohydrates are used as a source of energy. Excess carbohydrate can be stored as glycogen in
animal cells.
(a) Give two reasons why glycogen is used as a storage molecule.

Answer 24

• Compact and insoluble