Energy, Carbohydrates And Fats

Question 1

General formula for carbohydrates

Answer 1

Cx(H2O)y
e.g glucose is C6H12O6
Sucrose is C12H22O11

Question 2

Monomer, monomer pair and polymer of carbohydrates

Answer 2

Carbohydrate, monosaccharide, polysaccharide

Question 3

Draw alpha glucose

Answer 3

…

Question 4

Draw beta glucose

Answer 4

…

Question 5

Lactose

Answer 5

• glucose + galactose
• 1,4 glycosidic bond
• uses in mammalian milk

Question 6

Maltose

Answer 6

• glucose + glucose
• 1,4 glycosidic bond
• used to make seeds germinate and digest starch

Question 7

Sucrose

Answer 7

• fructose + glucose
• 1,2 glycosidic bond
• use in sugary foods, storage and sugar transport in plants.

Question 8

What are the 2 forms of starch?

Answer 8

amylose and amylopectin

Question 9

Amylose structure

Answer 9

• unbranched
• 1,4 glycosidic bonds
• very compact (more compact that amylopectin)
• made of alpha glucose molecules

Question 10

Amylopectin

Answer 10

• branched structure (lots of ends)
• 1,4 and 1,6 glycosidic bonds
• compact (less so than amylose)
• made of alpha glucose molecules

Question 11

Starch function determined by structure.

Answer 11

Both:
- key storage molecules in plants so can store lots of glucose in the form of starch which can be broken down to be used as energy.
- insoluble and large so good for storage
Amylopectin:
- is branched and has many ends so enzymes can act on it and hydrolyse it more quickly to form alpha glucose that is available for respiration.

Question 12

Glycogen structure

Answer 12

• Similar to starch (1,4 and 1,6 glycosidic bonds)
• but even more highly branched
• found in animal cells
• shorter chains than starch
• made of alpha glucose molecules

Question 13

Glycogen function determined by structure

Answer 13

• more highly branched than starch so that it can be hydrolysed into alpha glucose even more quickly
• storage molecule
• broken down into alpha glucose molecules for respiration

Question 14

Cellulose structure

Answer 14

• made of monomers of beta glucose molecules
• 1,4 glycosidic bonds
• straight (linear), unbranched chains that run parallel to each other
• lots of hydrogen bonds that form cross linkages

Question 15

Cellulose function determined by structure

Answer 15

• major component of plant cell walls and provides rigidity to the plant cell to prevent bursting
• structural molecule
• hydrogen bonds form cross linkages with each other to strengthen the cellulose (lots of them as hydrogen bonds are weak individually)

Question 16

Glycosidic bond

Answer 16

Covalent bond between two monosaccharides

Question 17

Peptide bond

Answer 17

Covalent bond between two amino acids

Question 18

Ester bond

Answer 18

Covalent bond formed between a fatty acid and a glycerol.

Question 19

Lipids/fat properties

Answer 19

• lipids are waterproof, fatty tail is hydrophobic.
• very compact so fatty stores of energy for organisms due to large number of carbon - hydrogen bonds that are hydrolysed to release energy. Also insoluble in water.
• thermal insulators, due to hydrophilic compounds, poor conductors.

Question 20

HDL (high density lipoproteins)

Answer 20

Formed from unsaturated fats, proteins and cholesterol and transports cholesterol from body tissues to the liver where it’s broken down. It reduces the cholesterol levels and the risk of atherosclerosis.

Question 21

LDL (low density lipoproteins)

Answer 21

Formed from saturated fats, protein and cholesterol and transports cholesterol from the liver to the blood, thus causing cholesterol levels to increase, so is linked to atherosclerosis risk increasing.