Biological Molecules

Question 1

What is a monosaccharide?

Answer 1

Single monomer sugar e.g. glucose, galactose, fructose

Question 2

What is a dissacharide?

Answer 2

Sugar made from two monosaccharide polymers e.g. maltose, sucrose, lactose

Question 3

What is a polysaccharide?

Answer 3

Polymers made from many monosaccharide (sugar) molecules e.g. starch, glycogen, cellulose.

Question 4

What reaction forms polysaccharides?

Answer 4

Condensation reaction

Question 5

What reactions breaks down polysaccharides?

Answer 5

Hydrolysis reaction

Question 6

What bond joins two sugar molecules?

Answer 6

Glycosidic bond

Question 7

What is the test for reducing sugars?

Answer 7

Add equal volume of benedicts solution to the food sample, gently heat in a water bath, if sugar present it will turn red/orange

Question 8

What is the test for non-reducing sugars?

Answer 8

If test for non-reducing sugar is negative take a fresh sample and add hydrochloric acid then neutralise with sodium hydrogen carbonate solution. Then add equal volume of benedicts and repeat test for reducing sugar.

Question 9

What is the difference between alpha and beta glucose?

Answer 9

Their H and OH groups are on different positions in the carbon ring

Question 10

Give two adaptations of starch

Answer 10

Insoluble, large, compact, easily hydrolyzed/can be broken down easily

Question 11

Give two adaptations of glycogen

Answer 11

Insoluble, compact, highly branched so can be broken down easily

Question 12

Give two adaptations of cellulose

Answer 12

Long straight chains, chains run parallel, chains grouped in microfibrils, strong

Question 13

Explain the difference between starch and cellulose

Answer 13

Starch is a coiled storage molecule.

Cellulose is a straight structural molecule

Question 14

What is a trigylceride?

Answer 14

Molecule made from three fatty acids and a glycerol molecule

Question 15

What is a phospholipid?

Answer 15

Molecule made from two fatty acids, a glycerol molecule and a phosphate molecule

Question 16

What bond joins fatty acids to glycerol?

Answer 16

Ester bond

Question 17

What reaction joins fatty acids to glycerol?

Answer 17

Condensation reaction

Question 18

Name some roles of lipids within the body

Answer 18

Source of energy, waterproofing, insulation, protection

Question 19

What do the terms hydrophilic and hydrophobic mean?

Answer 19

Hydrophilic - Interacts/attracted to water

Hydrophobic - Moves away from water

Question 20

Give two adaptations of triglycerides

Answer 20

Good energy source, large amounts of energy in a small volume, insoluble, water source

Question 21

Give two adaptations of phospholipids

Answer 21

Polar so form bilayer (for cell membranes), can form glycolipids

Question 22

What is the test for lipids?

Answer 22

Put 2cm^3 sample of food into a clean test tube and add 5cm^3 of ethanol. Shake tube thoroughly to dissolve. Add 5cm^3 water and shake. Cloudy emulsion indicates fat is present.

Question 23

Name the 4 key parts of an amino acid

Answer 23

Amino group, carboxyl groups, hydrogren atom, R group

Question 24

What bond joins amino acids together?

Answer 24

Peptide bond

Question 25

What is the primary structure of a protein?

Answer 25

The combination/sequence of different amino acids joined together in the polypeptide

Question 26

What is the secondary structure of a protein?

Answer 26

3D shape of the polypeptide chain caused by hydrogren bonds between the NH and CO groups

Question 27

What is the tertiary structure of a protein?

Answer 27

Secondary structure that is twisted and folded by further bonds such as disulfide bridges, ionic bonds and hydrogen bonds

Question 28

What is the quaternary structure of a protein?

Answer 28

A complex molecule made from several different polypeptide chains that are linked together

Question 29

Explain why heat and pH can change the structure of a protein

Answer 29

Extreme heat and pH can break the bonds in the tertiary and secondary structures causing the protein to lose it’s 3D shape.

Question 30

What is the test for proteins?

Answer 30

Add biurets reagent to the sample and check for colour change. If it goes purple a protein is present.

Question 31

Name the two types of protein

Answer 31

Fibrous and globular

Question 32

Explain how fibrous proteins are suited to their function.

Answer 32

Structural function, closely packed, tightly wound, with several fibres twisted to form strong fibres.

Question 33

Explain how globular proteins are suited to their function.

Answer 33

Metabolic function, soluble molecules, specific shape.

Question 34

Give examples of different types of proteins within the body.

Answer 34

Enzymes, antibodies, haemoglobin, collagen, keratin, muscles ect.