Carbohydrates

Question 1

Two types of glucose

Answer 1

Alpha glucose and beta glucose

Question 2

What are carbohydrates made of

Answer 2

Carbohydrates are made of sugars or polysaccharides. Sugars can be made of monosaccharides or disaccharides

Question 3

An example of a monosaccharide

Answer 3

Glucose

Question 4

What are the two types of glucose

Answer 4

Alpha and beta

Question 5

Difference between alpha and beta glucose

Answer 5

Alpha glucose has H on top of OH on carbon 1. While beta has OH over H in carbon 1 for beta glucose

Question 6

How are disaccharides formed

Answer 6

They are formed when two monosaccharides units join together by glycosidic bond in a condensation reaction.

Question 7

Examples how disaccharides are formed

Answer 7

Glucose + Glucose = Maltose

Glucose + fructose = sucrose

Glucose + galactose = lactose

Question 8

Two types of Starch

Answer 8

Alpha glucose can be joined together to form two different types of polysaccharides by glycosidic bonds. There is amylose and amylopectin.

Question 9

Structure of Amylose

Answer 9

Amylose is formed with bond between carbon 1 and 4. The bond s are at an angle meaning it twists into a helix, making it more compact and less soluble.

Question 10

Structure of Amylopectin

Answer 10

Has bonds between carbon 1 and 4 as well as carbon 1 and 6. This means amylopectin has a branched structure. Branches means there are more free ends to add and remove glucose making it good for energy storing.

Question 11

Function of Glycogen

Answer 11

The energy storage molecule in animals and fungi.
Glycogen forms more branches than amylopectin making it more compact. They are insoluble, compact, branched meaning it is suitable for a storage role.

Question 12

What is Cellulose and its structure

Answer 12

Is a straight chain of beta glucose. Beta cannot join the same way as alpha glucose as they cannot share an oxygen molecule, meaning one has to be turned upside down.
Cellulose make hydrogen bonds with each other forming microfibrils.
These microfibrils join to make macrofibrils, which combine to make fibres.

Question 13

Function of Cellulose

Answer 13

The fibres that make up cellulose is strong, insoluble and used to make cell walls. It is important to our diet because when broken down it forms fibres which are needed for our digestive system.

Question 14

What is a reducing sugar

Answer 14

Sugars that donate electrons to another molecule or chemical

Question 15

Benedict’s test

Answer 15

Is a test for reducing sugars.
1. Grind up sample and blend it with water
2. Add an equal volume of Benedict Reagent
3. Heat mixture in boiling water bath
The addition of electrons in blue cu^2+ ions reduce them to ca^+ ions. Turning them brick red.

Question 16

Iodine test

Answer 16

Test for starch.
Few drops of iodine dissolved in potassium iodine solution are mixed with a sample. If solution change purple/black starch is present.

Question 17

Non reducing sugar sucrose

Answer 17

Add dilute hydrophilic acid to sucrose. Place in water bath. Then add an alkali to neutralise the acid.
The do the reducing sugar test.
The acid hydrolyses the sucrose.
Then do the reducing sugar test and if it was a non reducing sugar this time it will be brick red

Question 18

Reagent strips

Answer 18

Are strips that test for the presence of reducing sugars particularly glucose. It is determined by a colour coded chart