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AQA A Level Biology Topic 1 > Carbohydrates > Flashcards

Carbohydrates Flashcards

1
Q

Which type of reaction joins biological monomers in order to create biological polymers?

A

Condensation reactions join monomers to create biological polymers which are larger more complex molecules. In the condensation reaction two things happen

  1. A glycosidic bond is made
  2. A water molecule is produced
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2
Q

Which type of reaction breaks biological polymers down into their biological monomers?

A

Biological polymers are usually broken down by hydrolysis reactions. Use a water molecule to hydrolyse/break glycosidic bond.

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3
Q

What does the term ‘sugars’ refer to?

A

Monosaccharides and disaccharides.

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4
Q

Name 3 monosaccharides.

A

Glucose
Fructose
Galactose

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5
Q

Which elements do carbohydrates contain?

A

Carbon
Oxygen
Hydrogen

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6
Q

Name the two different isomers of glucose.

A

Alpha-glucose and beta-glucose

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7
Q

Explain the orientation of the H and OH groups on the first carbon in the hexose sugars alpha-glucose and beta-glucose?

A

Alpha-glucose: the H groups are on top and OH groups on bottom

Beta-glucose: a H group and OH group on top and bottom

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8
Q

What is a monosaccharide?

A

A monomer of a polysaccharide which is a carbohydrate.

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9
Q

What is created when two monosaccharides are joined in a condensation reaction?

A

A disaccharide and a molecule of water.

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10
Q

What happens when a disaccharide is hydrolysed?

A

1.The glycosidic bond breaks using a molecule of water
2. Disaccharide separates into two monosaccharides

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11
Q

Which disaccharide is produced when two monosaccharides of glucose join in a condensation reaction?

A

Maltose

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12
Q

Which disaccharide is produced when two monosaccharides of glucose and fructose join in a condensation reaction?

A

Sucrose

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13
Q

Which disaccharide is produced when two monosaccharides of glucose and galactose join in a condensation reaction?

A

Lactose

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14
Q

What is a reducing sugar?

A

A sugar that readily loses electrons to another substance. It reduces other substances by giving electrons (TIP: OIL RIG)

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15
Q

How do you test for a reducing sugar?

A
  1. add sample to test tube
  2. add excess Benedicts reagent
  3. heat using water bath

+ve: colour change and precipitate
-ve: remains blue

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16
Q

How do you test for a non-reducing sugar?

A
  1. carry out test for reducing sugar
  2. add a new sample to test tube
  3. add HCl and heat in water bath
  4. add sodium hydrogencarbonate to neutralise the acid
  5. add excess Benedicts reagent
  6. heat using water bath

+ve: colour change and precipitate
-ve: remains blue

17
Q

What is a polysaccharide?

A

A large chain of monosaccharides all held together by glycosidic bonds.

18
Q

Name 3 polysaccharides.

A

Starch
Glycogen
Cellulose

19
Q

What is the monomer of starch?

A

Alpha glucose

20
Q

Explain the structure of starch

A
  1. Polysaccharide made up of alpha glucose molecules
  2. Amylose: coiled, unbranched chains with 1,4 glycosidic bonds
  3. Amylopectin: straight, branched chains with 1,4 glycosidic bonds and 1,6 glycosidic bonds
21
Q

What is the function of starch?

A

Stores energy in plants

22
Q

Starch is insoluble in water. How would this support its function?

A
  1. Doesn’t affect water potential - water can’t move into cell by osmosis causing it to swell
  2. Makes an ideal storage molecule
23
Q

What are 3 properties of starch that make it suitable for its function?

A
  1. insoluble - doesn’t affect water potential
  2. compact - a lot of energy can be stored in a small space
  3. branched - glycosidic bonds can be hydrolysed easily to release energy quickly
24
Q

What is the monomer of glycogen?

A

Alpha glucose

25
Q

Explain the structure of glycogen.

A
  1. polysaccharide of alpha glucose molecules
  2. highly branched - has 1,4 glycosidic bonds and 1,6 glycosidic bonds
26
Q

What is the function of glycogen?

A

Stores energy in animals/stores excess glucose as glycogen

27
Q

Where is glycogen found in animals?

A

Primarily in the muscles and liver.

28
Q

Glycogen is insoluble. How is that important?

A
  1. Doesn’t affect water potential - water can’t enter cell and cause it to be hemolysed (cause death)
  2. Makes an ideal storage molecule
29
Q

What is the monomer of cellulose?

A

Beta glucose

30
Q

Explain the structure of cellulose.

A
  1. Long straight chains made up of beta glucose molecules
  2. 1,4 glycosidic bonds
  3. straight chains linked together by hydrogen bonding forming strong fibres called microfibrils
31
Q

What is the function of cellulose?

A

Provides structural support to cell wall. Keeps it stable and intact by preventing them to burst.

32
Q

How would you test for starch?

A
  1. add sample to test tube
  2. add iodine solution and shake

+ve: blue-black
-ve:brown-yellow

AQA A Level Biology Topic 1 (2 decks)

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