Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Carr > PRAC QUESTIONS > Flashcards

PRAC QUESTIONS Flashcards

1
Q

desc how to carry out test for presence of lipids in a liquid sample of food (2)

A
  1. Add ethanol
  2. Then add water
  3. Shake
  4. white/milky emulsion forms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

2/3

desc how a triglyceride is formed (3)

A
  1. it consists of 1 glycerol and 3 fatty acids. these molecules join together to form triglyceride via condensation reaction, which involves forming a bond between the molecules through the elimination of 3 molecules of water (for the 3 fatty acids)
  2. ester bonds are formed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

desc how an ester bond is formed in a phospholipid molecule (2)

A
  1. condensation reaction
  2. between the glycerol and fatty acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

desc how you’d test a liquid sample for the presence of lipid and how you’d recognise a positive result (2)

A
  1. (Mix / shake sample) with ethanol, then water;
    Sequence is important
  2. White / milky (emulsion);
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

desc how you’d test a piece of food for the presence of lipid (2)

A
  1. dissolve in alcohol THEN add water
  2. white emulsion shows presence of lipid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

the scientists expressed their results as percentage of lipid in plasma membrane by mass explain how they’d find these results (2)

A
  1. divide mass of each lipid by total mass of all lipids (in that type of cell)
  2. multiply answer by 100
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

a biochemical test to show that raffinose sol contains a non-red sugar (3)

A
  1. heat w acid
  2. heat w benedict’s sol
  3. red precipitate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

other than using colorimeter how can student measure quanitity of red sugar in sol (2)

A

filter sol and then dry and nweigh it. the heavier it is the more concentrated it is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

use of a colorimeter in this investigation would improve nrepeatability of results, why? (1)

A

quantitative –> standardises the method

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

1 similarity and 1 difference between strcuture is lactulose and lactose

A

SIMILAR - both contain galactose, a glycosididc bond
DIFFERENCE- lactulose contains fructose, whereas lactose contains glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

desc 2 differences between the strcuture of cellulose molecule and glycogen molecule (2)

A
  1. cellulose= straight chain, glycogen is branched, only has 1,4 glycosidic bonds
  2. glycogen has 1,4 and 1,6 glycosidic bonds and
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

suggest how glycogen acts as a source of energy (2)

A
  1. hydrolysed to glucose
  2. glucose used in respiration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

1 difference in strcuutre of starch and cellulose molecule

A

position of hydrogen hydroxyl groups on carbon atom 1 inverted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

explain how cellulose molecules are adapted for their function in plant cells (3)

A
  1. long and straight chains
  2. become linked together by many hydrogen bonds to form fibrils
  3. provide strength to cell wall
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

desc the induced fit model of enzyme action AND how an enzyme acts as a catalyst (3)

A
  1. substrate binds to the active site therefore forming an enzyme-substrate complex
  2. active site chnages shape (slightly) so its complimnetary to substrate
  3. reduces activation energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

suggest and explain a procedure the scientists could have used to stop each reaction (2)

A
  1. Boil
  2. Denatures the enzyme/ATP synthase;
17
Q

explain the change in ATP conc with increasing inorganic phosphate conc (2)

A

1.(With) increasing Pi concentration, more enzyme- substrate complexes are formed;
2.At or above 40 (mmol dm-3) all active sites occupied

18
Q

explain how a compeitive inhibiotr decreases the rate of an enzyme-controlled reaction (3)

A
  1. Inhibitor similar shape to substrate;
  2. Fits/binds to active site;
  3. Prevents/reduces enzyme-substrate complex forming;
19
Q

explain how eating stale bread could help to reduce weight gain (bc the strcutre of some starch is chnaged when bread is stale) (3)

A
  1. Less hydrolysis of starch;
  2. (To) maltose;
  3. (So) less absorption (of glucose)
20
Q

desc how the structure of a protein depends on the aa it contains (5)

A
  1. Structure is determined by (relative) position of amino acid/R group/interactions;
  2. Primary structure is sequence/order of amino acids;
  3. Secondary structure formed by hydrogen bonding (between amino acids)
  4. Tertiary structure formed by interactions (between R groups);
  5. Creates active site in enzymes
  6. Quaternary structure contains >1 polypeptide chain
21
Q

desc how to amino acids join to form a polypeptide so theres always NH2 at one end and COOH at the other (2)

A
  1. One amine/NH2 group joins to a carboxyl/COOH group to form a peptide bond;
  2. (So in chain) there is a free amine/NH2 group at one end and a free carboxyl/COOH group at the other
22
Q

explain how the active site of an enzyme causes a high rate of reaction (3)

A
  1. Lowers activation energy;
  2. Induced fit causes active site (of enzyme) to change shape;
  3. (So) enzyme-substrate complex causes bonds to form/break;
23
Q

desc 2 other ways in which all dipeptides are similar and 1 way in which they might differ (3)

A

SIMILAR:
1. Amine/NH2/ COOH(group at end);
2. Two R groups

DIFFERENCE:
Variable/different R group(s);

24
Q

desc how a non-competitive inhibitor can reduce the rate of reaction of an enzyme controlled reaction (3)

A
  1. Attaches to the enzyme at a site other than the active site;
  2. Changes (shape of) the active site
  3. (So active site and substrate) no longer complementary so less/no substrate can fit/bind;
25
Q

looking at the graph suggest how the scientist concluded pectin is a non-competitive inhibitor (1)

(pectin added line is straight)

A

(With inhibitor) increase substrate/lipid (concentration) does not increase/affect/change rate of reaction

26
Q

desc how a peptide bond is formed between 2 aa to form a dipeptide

A

Condensation (reaction) / loss of water
Between amine / NH2 and carboxyl / COOH

27
Q

the secondary structure of a polypeptide is produced by bonds between aa explain how (2)

A

Hydrogen bonds;
Forming β pleated sheets

28
Q

Two proteins have the same number and type of amino acids but different tertiary structures.
Explain why.

A

Different sequence of amino acids
Forms ionic / hydrogen / disulfide bonds in different places;

29
Q

Formation of an enzyme-substrate complex increases the rate of reaction. Explain how.

A

Reduces activation energy;
Due to bending bonds

30
Q

explain why lipids give a positive result in the emulsion test

A

lipids cannot dissolve in water so if they’re present, they form an emulsion

31
Q

explain how the strucutre of glycogen makes it well-suited to its function

A

it has lots of side branches meaning stored glucose can be released quickly

32
Q

cellulose is made of long, straight chains qith multiple hydeogen bonds between the chains, explain how this makes it well suited to its function

A

allows cellulose molecules to form strong fibres/microfibrils, which provide structural support

33
Q

desc how to carry out buiret test and what the +ve result would be

A
  1. add a few drops of NaOH to sol. of sample
  2. add a few drops of copper ii sulfate sol
  3. a colour change from blue—- purple is a positive result
34
Q

protein A is made of long polypeptide chain lying parallel to one another with cross linkages between. Explain why its strucutre is well-suited to being a structural protein

A

uts parallel chains and cross linkages make it physically strong

35
Q

protein B= Tightly folded polypep chain and roughly spherical in shape
Protein C= Made of 2 light polypep. chains and 2 heavy polypep chains

how does the body use the above

A

b= enzyme (typical spherical strucure is an enzyme)
c= antibody (usually consits of 2 heavy and 2 light chains)

36
Q

function of channel protein 3

A

transport molecules and ions across cell membranes - the hydrophobic regions are repelled by water and the hydrophilic regions are attracted to it- this enables the protein to fold up and form a channel through the membrane (through which water soluble molecule can pass)

Carr (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions