exam prep

Question 1

describe a chemical test you could carry out ti show a thing contains lipids (3)

Answer 1

-crush in ethanol
-add to water
-white emulsion

Question 2

describe how you would use a biochemical test ti show a sample contained a reducing sugar (2)

Answer 2

-benedict’s and heat
-green/yellow/orange/red

Question 3

describe how you would use a biochemical test to show a solution contained protein (2)

Answer 3

-biuret
-purple

Question 4

explain what is meant by a polymer (1)

Answer 4

molecule made up of many similar molecules

Question 5

describe how the sequence of amino acids in part of a protein from a persons years could enable this protein to act as an enzyme inhibitor(6)

Answer 5

1. sequence of AA gives shape
   2.this is a tertiary structure
   3.has similar shape to substrate
   4.competes for active site
2. fits at allosteric site
3. distorts active site

Question 6

explain how proteins are suited for their roles as receptor molecules (4)

Answer 6

1. many different sorts of proteins
2. different primary structures
3. shape allows formation of receptor site into which
4. substrate fits

Question 7

explain how the structure if fibrous proteins is related to their functions (7)

Answer 7

-long chains of AA
- chains fold into helix or pleated sheets
-many polypeptide chains together
-by hydrogen and disulphide bonds
-fibres provide strength
-sheets provide flexibility
-e.g collagen in bones

Question 8

unsaturated differs ti a saturated

Answer 8

absence if double bonds in a hydrocarbon chains unable to accept more hydrogen

Question 9

desc structure of cellulose and explain how cellulose is adapted for its function in cells (6)

Answer 9

1. b glucose
   2.joined by condensation
   3.1:4 link between carbon atoms
   4.hydrogen bonds link long straight chains
2. cellulose makes cell walls strong
   6.bonds are difficult to break

Question 10

explain how the properties if starch are related to its role in living organisms (4)

Answer 10

• role is storage & insoluble
  -stays inside the cell
  -coiled molecule
  -lots of glucose in a small space

Question 11

explain how cellulose gives cotton it’s strength (3)

Answer 11

• straight unbranched chains
  -multiple chains form microfibrils
• hydrogen bonds hold chains together

Question 12

explain how structure of cellulose is linked to its function (2)

Answer 12

• hydrogen bonds
  -strength

Question 13

two ways in which structure if cellulose is different from structure if starch (2)

Answer 13

starch is a glucose
cellulose b glucose

Question 14

explain how a change in the primary structure if a globular protein may result ins. different 3d structure (3)

Answer 14

-sequence of AA changes
-tertiary structure folds in a different way
- bonds form in different places

Question 15

describe the structure of an aa molecule and how they link together (6)

Answer 15

1. aa based on carbon with 4 groups attatched
   2.amino group, carboxyl group
2. R-group by side chain
   4.R-group differs from one aa to another
   5.aa joined by condensation
   6.bomd forms involves removal of molecule of water

Question 16

explain how amino acid molecules may be linked to form a polypeptide chains unable which is folded into a specific tertiary shape (6)

Answer 16

• condensation
  -removal of water molecule
  -from amino and carboxyl groups
  -forming peptide bonds
  -same aa in same sequence
  -bonds form between r - groups

Question 17

desc how y could use benedicts reagent to test urine for presence of reducing and non reducing sugars (4)

Answer 17

-add benedicts reagent to urine and heat
-turn green/yellow/orange/red
-heat with acid then neutralise
-heat with benedict’s solution