Biological Molecules

Question 1

Define condensation

Answer 1

When two monomers are joined together with the removal of a water molecule.

Question 2

E.G of monomers

Answer 2

Glucose , amino acids and nucleotides (monosaccharides)

Question 3

Define hydrolysis

Answer 3

Water is added to break a bond between two molecules

Question 4

E.g. of disaccharides

Answer 4

Sucrose, maltose and fructose

Question 5

E.g of polysaccharides

Answer 5

glycogen, starch and cellulose

Question 6

Benedicts test (reducing sugar)

Answer 6

Add food sample and benedict’s reagent and gently heat. If solution turns brick red then reducing sugar is present.

Question 7

Benedicts test (non- reducing sugar)

Answer 7

If there is no colour change then get a new sample and add HCl to break up disaccharides/polysaccharides and heat . Add NaHCO3 to neutralise the acid. Then add benedicts reagent and gently heat , if it turns brick red , non-reducing sugar is present.

Question 8

Test for starch

Answer 8

Iodine , solution will turn blue-black from orange if starch is present

Question 9

Properties of glycogen

Answer 9

Made from alpha glucose
1-4 + 1-6 glycosidic bonds
Branched (energy released easily)
Large and compact (store a lot of energy)
Insoluble (not affected by osmosis)

Question 10

Properties of starch (amylose)

Answer 10

Made from a-glucose
Insoluble
Unbranched
1-4 glycosidic bond
Compact

Question 11

Properties of starch (amylopectin)

Answer 11

Made from a-glucose
Branched
Insoluble
1-4 + 1-6 glycosidic bond

Question 12

Properties of cellulose

Answer 12

Made from B- glucose
Unbranched
Can form microfibrils which are cellulose chains that run parallel to one another joined by hydrogen bonds for collective strength

Question 13

Main type of lipids

Answer 13

Phospholipids and triglycerides

Question 14

Saturated lipids have …

Answer 14

no carbon-carbon double bonds

Question 15

Unsaturated lipids have..

Answer 15

carbon-carbon double bonds that allows it to bend and be a kinky molecule

Question 16

How triglycerides structure is important for their function?

Answer 16

Large and non-polar , so isnt affected by osmosis

High ratio of H-O atoms , so triglycerides release water when they are oxidised and can provide an important source of water for organisms in dry environments.

Question 17

Test for lipids

Answer 17

Add ethanol to smaple and shake to dissolve lipid in solution .

Add water and shake gently. White emulsions appear of lipid is present.

Question 18

Globular proteins are…

Answer 18

enzymes and are compact

Question 19

Fibrous protiens are…

Answer 19

long and used to form fibres like keratin

Question 20

Test for proteins

Answer 20

Add Biuret reagent to sample, if a purple colouration appears a protein is present , If it remains blue no protein.

Question 21

Factors that affect the rate of enzyme controlled reactions and why

Answer 21

1. Temperature increases the rate of reaction but to high and enzyme becomes denatured due to breaking of bonds that holds the tertiary structure

2.pH every enzyme has an optimum pH too high or low enzyme denatures

3. Enzyme/substrate concentration
4. Inhibitors