Digestion And Carbohydrates Flashcards Preview

AQQ As Level Biology Unit One > Digestion And Carbohydrates > Flashcards

Flashcards in Digestion And Carbohydrates Deck (24)
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0
Q

What are the monomers called in carbohydrates?

A

Monosaccharides

1
Q

What are carbohydrates used for?

A

Energy source / store (glucose, starch, glycogen)

Structure (cellulose)

2
Q

Give some properties of monosaccharides

A

Small molecules - easily absorbed and transported

Highly soluble

3
Q

What is the difference between alpha and beta glucose?

A

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

4
Q

What elements do all carbohydrates contain?

A

Oxygen, hydrogen and carbon

5
Q

What is a disaccharide?

A

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

6
Q

What is maltose hydrolysed by and into what?

A

Maltase into two glucose molecules

7
Q

What is sucrose hydrolysed by and what into?

A

Sucrase into glucose and fructose

8
Q

What is lactose hydrolysed by and what into?

A

Lactase into glucose and galactose

9
Q

How are disaccharides formed?

A

By a condensation reaction between two monosaccharides (produces water)

10
Q

How are disaccharides split up into two monosaccharides?

A

By a hydrolysis reaction (add water)

11
Q

What is the bond called between monosaccharides?

A

Glycosidic bond (it is a covalent bond)

12
Q

What is the formula of a disaccharide?

A

C12H22O11 (water produced)

13
Q

What is starch made up of?

A

Amylose and amylopectin

14
Q

What carbons are the glycosidic bonds between in disaccharides?

A

Carbon one and four

15
Q

What is a polysaccharide?

A

Many monosaccharides joined together by glycosidic bonds

16
Q

Give two examples of polysaccharides

A

Amylose
Amylopectin
Cellulose

17
Q

What is lactose intolerance?

A

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

18
Q

What and how is caused by lactose intolerance?

A

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

19
Q

How can you prevent conditions from lactose intolerance?

A

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

20
Q

What is the formula of glucose / monosaccharides?

A

C6H12O6

21
Q

What and how is the test for reducing sugars?

A

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

22
Q

How is starch digested?

A

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

23
Q

What and how is the test for starch?

A

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