3.3 Carbohydrates Flashcards
What is a single sugar known as? (1 mark)
Monosaccharide
What are two or more monosaccharides linked together called? (1 mark)
Polysaccharides
Give an example of a polysaccharide. (1 mark)
Glycogen
Cellulose
Starch
What is eye formula for glucose? (1 mark)
C6H12O6
In alpha glucose, are the hydroxyl groups on the same side or opposite sides? (1 mark
Same side, bottom
In beta glucose, are the hydroxyl groups on the same side or opposite sides? (1 mark)
Opposite, one on top and one on bottom
Are glucose molecules polar? (1 mark)
Yes.
Why is glucose soluble? (2 marks)
Due to the hydrogen bonds forming between the hydroxyl groups and water molecules.
What is a condensation reaction? (2 marks)
The joining of two molecules by removing a water molecule.
What is the covalent bond that links sugars called? (1 mark)
Glycosidic bond
What type of bond do glucose molecules get joined together by? (2 marks)
1,4- glycosidic bond
What is a molecule made up of two monosaccharides called? (1 mark)
Disaccharide
What are two glucose molecules bonded together with a 1,4-glycosidic bond called? (1 mark)
Maltose
What are the disaccharides in maltose? (2 marks)
2 glucose molecules
What are the monosaccharides in the disaccharide sucrose? (2 marks)
1 glucose molecule
and 1 fructose molecule
What disaccharide is formed when a molecule of glucose and a molecule of fructose bond? (1 mark)
Sucrose
What are the disaccharides in lactose? (2 marks)
1 glucose molecule
and 1 galactose molecule
What disaccharide is formed when a molecule of glucose and a molecule of galactose bond? (1 mark)
Lactose
Put the following sugars in order of sweetness:
Glucose, galactose, fructose
(2 marks)
Most sweet: Fructose
Glucose
Least sweet: Galactose
What is a pentose monosaccharide? (1 mark)
A sugar that contains five carbon atoms.
What is a sugar that contains five carbon atoms called? (1 mark)
pentose monosaccharide
Give two examples of pentose monosaccharides. (2 marks)
Ribose
Deoxyribose
Where is ribose present? (1 mark)
In RNA nucleotides
Where is deoxyribose present? (1 mark)
In DNA molecules
Name the two polysaccharides classed as ‘starch’. (2 marks)
Amylose
Amylopectin
What is the main function of starch in plants? (1 mark)
To store glucose made in photosynthesis.
Is amylose a straight or branched polymer? (1 mark)
Straight
Is amylopectin a straight or branched polymer? (1 mark)
Branched
How are the glucose molecules in amylose bonded together, and what shape does this form? (2 marks)
Joined together by 1-4 glycosidic bonds, this long chain of glucose molecules twists to form a helix.
How is the structure of amylose stabalised? (1 mark)
With hydrogen bonding within the molecule.
Why is amylose less soluble than glucose?
It has a compact, helix structure stabalised with hydrogen bonds within the molecule.
How are the glucose molecules in amylopectin bonded together? (2 marks)
A chain of glucose molecules joined together by 1-4 glycosidic bonds, with branches joined on with 1-6 glycosidic bonds.
How is energy stored in animals and fungi, and why is it more efficient than amylopectin? (
As glycogen, it is more branched than amylopectin, making it more compact (so less space is needed for it to be stored.
How are amylopectin and glycogen suited for their roles? (2 marks)
They are insoluble, branched, and compact.
What is a hydrolysis reaction? (2 marks)
The breaking of a bond by adding a molecule of water.
What is cellulose made up of? (2 marks)
Beta glucose molecules joined together with 1-4 glycosidic bonds.
Explain why cellulose is a straight chain molecule, by describing its structure. (3 marks)
It is a long chain of beta glucose molecules. The only way beta glucose molecules can bond together are if alternate molecules are upside down, if they weren’t the hydroxyl groups would be too far away from each other to form a glycosidic bond. This structure makes, the polysaccharide formed unable to form branches.
Describe the composition of the fibres in cell walls. (3 marks)
Cellulose molecules hydrogen bond with each other to form microfibrils.
The microfibrils join together to form macrofibrils.
The macrofibrils combine to form fibres.
Why is cellulose used in cell walls? (2 marks)
It is strong and insoluble.
Identifyu two similarities between starch and glycogen. (2 marks)
Both made up of glucose monomers.
Both stored as granules.
