carbohydrates

Question 1

What are monosaccharides

Answer 1

-Monosaccharides are the monomers from which larger carbohydrates are made. Glucose, galactose and fructose are common monosaccharides

Question 2

What bond formed in a condensation reaction between 2 monosaccharides

Answer 2

-Glycosidic bond

Question 3

How are disaccharides formed

Answer 3

-Condensation of 2 monosaccharides

Question 4

Examples of disaccharides

Answer 4

-Sucrose, Maltose, Lactose

Question 5

How is maltose formed

Answer 5

-Maltose is a disaccharide formed by condensation of two glucose molecules

Question 6

How is sucrose formed

Answer 6

-Sucrose is a disaccharide formed by condensation of a glucose
molecule and a fructose molecule

Question 7

How is lactose formed

Answer 7

-Lactose is a disaccharide formed by condensation of a glucose
molecule and a galactose molecule.

Question 8

What is an isomer and give an example

Answer 8

-Isomers are compounds that have the same molecular formula but are structurally different
-Glucose has 2 isomers a and b

Question 9

How are polysaccharides formed

Answer 9

-Polysaccharides are formed by the combination of a large number of monosaccharides through the glycosidic bond.

Question 10

What are glycogen and starch made of

Answer 10

-Glycogen and starch are formed by the condensation of α-glucose.

Question 11

What is cellulose made of

Answer 11

-Cellulose is formed by the condensation of β-glucose.

Question 12

Structure of starch

Answer 12

-Mixture of two polysaccharides: amylose and amylopectin

-Amylose = long unbranched forms coiled/spring shape.

-Amylopectin = long branched chain due to 1-6 glycosidic bonds

Question 13

Structure of glycogen

Answer 13

-A long, branched chain with lots of side branches (more than amylopectin). The glycosidic bonds are also 1-6.

Question 14

Structure of cellulose

Answer 14

-Long unbranched straight chains. The glycosidic bonds are 1-4.

-The cellulose chains are then linked together by hydrogen bonds between the glucose molecules in each chain to form thicker fires called microfibrils.

Question 15

Properties of starch

Answer 15

-Amylose = coiling makes it
compact and stores more in a smaller space

-Amylopectin = branches
increase surface area for enzymes to hydrolyse glycosidic bonds allowing glucose to be released quickly

Question 16

Properties of glycogen

Answer 16

-Lots of branches increase surface area for enzymes to hydrolyse glycosidic bonds allowing glucose to be released quickly.
-It is also a compact molecule so it is good for storage.

Question 17

Properties of cellulose

Answer 17

-The hydrogen bonds between the cellulose chains make the microfibrils very strong but still flexible allowing them to provide support.

Question 18

Uses of starch

Answer 18

-Plants use starch as a way of storing excess glucose as it is too large to leave cells and insoluble (doesn’t dissolve in water - this also means it does not affect water potential).

-Starch can be hydrolysed to release glucose for respiration.

Question 19

Uses of glycogen

Answer 19

-Animals store excess glucose as glycogen in muscles and in the liver.

-Glycogen is therefore an energy store as it can be hydrolysed to release glucose quickly when needed for respiration e. g during exercise.

Question 20

Uses of cellulose

Answer 20

-Cellulose is a major structural component in the cell walls of plants, it provides support and allows cells to become turgid.