Digestion And Carbohydrates

Question 0

What are the monomers called in carbohydrates?

Answer 0

Monosaccharides

Question 1

What are carbohydrates used for?

Answer 1

Energy source / store (glucose, starch, glycogen)

Structure (cellulose)

Question 2

Give some properties of monosaccharides

Answer 2

Small molecules - easily absorbed and transported

Highly soluble

Question 3

What is the difference between alpha and beta glucose?

Answer 3

On beta glucose the OH on the carbon 1 is at the top, on alpha it is at the bottom.

Question 4

What elements do all carbohydrates contain?

Answer 4

Oxygen, hydrogen and carbon

Question 5

What is a disaccharide?

Answer 5

A carbohydrate that has two monosaccharides joined together (by a glycosidic bond)

Question 6

What is maltose hydrolysed by and into what?

Answer 6

Maltase into two glucose molecules

Question 7

What is sucrose hydrolysed by and what into?

Answer 7

Sucrase into glucose and fructose

Question 8

What is lactose hydrolysed by and what into?

Answer 8

Lactase into glucose and galactose

Question 9

How are disaccharides formed?

Answer 9

By a condensation reaction between two monosaccharides (produces water)

Question 10

How are disaccharides split up into two monosaccharides?

Answer 10

By a hydrolysis reaction (add water)

Question 11

What is the bond called between monosaccharides?

Answer 11

Glycosidic bond (it is a covalent bond)

Question 12

What is the formula of a disaccharide?

Answer 12

C12H22O11 (water produced)

Question 13

What is starch made up of?

Answer 13

Amylose and amylopectin

Question 14

What carbons are the glycosidic bonds between in disaccharides?

Answer 14

Carbon one and four

Question 15

What is a polysaccharide?

Answer 15

Many monosaccharides joined together by glycosidic bonds

Question 16

Give two examples of polysaccharides

Answer 16

Amylose
Amylopectin
Cellulose

Question 17

What is lactose intolerance?

Answer 17

If you do not have enough lactase (enzyme) you cannot breakdown lactose (in milk) this is called lactose intolerance

Question 18

What and how is caused by lactose intolerance?

Answer 18

Undigested lactose builds up in the small intestine it is fermented by bacteria producing gas causing stomach cramps, flatulence and diarrhoea

Also, the build up of lactose in the small intestine causes the solute concentration of the lumen to rise and the water potential to lower, this means water moves out of cells into the SI lumen via epithelial cells down the concentration gradient via osmosis. This build up of water causes diarrhoea

Question 19

How can you prevent conditions from lactose intolerance?

Answer 19

Artificially treat milk with purified lactase to make it suitable (it is already digested)

Question 20

What is the formula of glucose / monosaccharides?

Answer 20

C6H12O6

Question 21

What and how is the test for reducing sugars?

Answer 21

The Benedict’s test

Heat solution with Benedict’s reagent. If it changes from blue to brick red then reducing sugar is present

If it stays blue we can test for non-reducing sugar. Get a new sample, boil it with dulce hydrochloric acid, then neutralise it by adding sodium hydrogencarbonate. Do the same as the first step

Question 22

How is starch digested?

Answer 22

As it is made up of a mixture of polysaccharides, more steps are needed to break it down.

First it is broken down by amylase in the mouth to form maltose, then by maltose to form alpha glucose molecules

Question 23

What and how is the test for starch?

Answer 23

Iodine test

Add iodine dissolved in potassium iodide solution into the sample. If starch is present, the sample changes from browny orange into a dark, blue-black colour