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Biology Module 2 > PAGS (testings) > Flashcards

PAGS (testings) Flashcards

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1
Q

Test for reducing/nonreducing sugars

A

Benedict’s test

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2
Q

Diff between reducing + non reducing sugars

A

Reducing can act as reducing agents due to presence of free aldehyde or ketone group + non reducing can’t

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3
Q

Example of non reducing sugars

A

Sucrose

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4
Q

Colour of Benedict’s reagent

A

Blue

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5
Q

What does Benedict’s reagent contain

A

copper (Il) sulphate ions (CuSO4 )

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6
Q

What happens to the copper (Il) sulphate ions (CuSO4 ) in Benedict’s solution, when in contact with reducing sugars

A

Copper (I) oxide forms

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7
Q

Why does copper (I) oxide form a precipitate

A

Insoluble in water

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8
Q

Test for reducing sugars method

A
  • Add Benedict’s reagent to the sample in a test tube
    • Heat the test tube in a water bath for 2-3 mins
    Observe colour
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9
Q

Positive test - reducing sugar

A

Coloured precipitate will form

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10
Q

Importance of adding excess Benedict’s solution

A

so that there is more than enough copper (Il) sulfate present to react with any sugar present

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11
Q

Colour change for reducing sugars

A

from blue (no reducing sugar), through green, yellow and orange (low to medium concentration of reducing sugar) to brown/brick-red (a high concentration of reducing sugar)

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12
Q

Why is the reducing sugar test described as semi - quantitative

A

as the degree of the colour change can give an indication of how much (the concentration of) reducing sugar present

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13
Q

If there’s more reducing sugar…

A

Less blue cu 2+ ions left so lighter solution if precipitate is removed

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14
Q

Method for test for non reducing sugar

A
  • Carry out reducing sugar test first, if negative boil with dilute hydrochloric acid
  • neutralise w/ sodium hydrogen carbonate
  • carry out Benedict’s test
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15
Q

Why do we add a little more sodium hydrogen carbonate in the non-reducing sugars test

A

as the conditions need to be slightly alkaline for the Benedict’s test to work

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16
Q

Why do we add hydrochloric acid in the non-reducing sugars test

A

hydrolyse any glycosidic bonds present in any carbohydrate molecules

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17
Q

What test is used to identify starch

A

Iodine from potassium iodide

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18
Q

Method to test for starch

A

• add a few drops of orange/brown iodine in potassium iodide solution to the sample

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19
Q

Why do we use potassium iodide when testing for starch

A

Because iodine by itself is insoluble in water

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20
Q

Positive result = iodine starch test

A

blue-black/purple-black colour

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21
Q

What are reagent strips

A

can be used to test for the presence of reducing sugars, most commonly glucose.

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22
Q

What type of molecules are lipids

A

Non polar

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23
Q

Why do we add ethanol when identifying lipids

A

Cause ethanol is non-polar, so lipids (being non-polar) will dissolve in it

24
Q

What test do we use to identify lipids

A

Emulsion test

25
Q

Emulsion test method

A

Add ethanol to the sample to be tested
• Shake to mix
• Add the mixture to a test tube of water

26
Q

Emulsion test positive result

A

Milky cloudy emulsion will form

27
Q

Limitations of emulsion test

A

This test is qualitative - it does not give a quantitative value as to how much lipid may be present in a sample

28
Q

What test is used to identify proteins

A

Biuret test

29
Q

What does biuret reagent contain

A

Sodium hydroxide and copper (Il) sulphate which react in the presence of peptide bonds

30
Q

Method for biuret test

A

Add a few drops of biuret solution to sample.
If peptide bonds present then you’ll see it change from blue to a lilac colour

31
Q

Limitations of biuret test

A

if the sample contains amino acids or dipeptides, the result will be negative
• The Biuret test is qualitative - it does not give a quantitative value as to the amount of protein present in a sample

32
Q

Where are inorganic ions found

A

occur in solution in the cytoplasm and body fluids of organisms

33
Q

What is an inorganic ion

A

An ion that doesn’t contain carbon

34
Q

What do inorganic ions act as

A

Co factors

35
Q

What are co factors

A

non-protein chemical compounds that are required for a protein to function

36
Q

How many bonds does nitrogen form

A

3

37
Q

What does valency mean

A

Number of covalent bonds an atom can make.

38
Q

Chemical symbol + function of hydrogen ions

A

H+

Hydrogen bonding
• ATP formation
• Control of blood pH
• Transport of carbon dioxide

39
Q

Chemical symbol + function of calcium ions

A

Ca2+

• Cofactor in blood clotting
• Synaptic transmission of nerve impulses
• Muscle contraction

40
Q

Chemical symbol + function of iron ions

A

Fe2+/Fe3+

Transport of oxygen via haemoglobin
o Transfer of electrons
(respiration and photosynthesis)

41
Q

Chemical symbol + function of sodium ions

A

Na+

Nerve transmission
• Reabsorption of water in the kidneys

42
Q

Chemical symbol + function of potassium ions

A

K+

• Nerve transmission
• Reabsorption of water in the kidneys
• Opening of the stomata

43
Q

Chemical symbol + function of ammonium ions

A

NH4+

Deamination of proteins

44
Q

Cations we need to know

A

Hydrogen ions
Calcium ions
Iron ions
Sodium ions
Potassium ions
Ammonium ions

45
Q

Anions we need to know

A

Nitrate ions
Hydrogen carbonate ions
Chloride ions
Phosphate ions
Hydroxide ions

46
Q

Chemical symbol + function of nitrate ions

A

NO3-

Source of nitrogen for plants

47
Q

Chemical symbol + function of hydrogen carbonate ions

A

HCO3-

transport of co2 in your blood

48
Q

Chemical symbol + function of chloride ions

A

Cl-

• Maintaining pH balance during carbon dioxide transport

49
Q

Chemical symbol + function of phosphate ions

A

PO4 3-

component of phospholipids, nucleic acid, ATP

50
Q

Chemical symbol c function of hydroxide ions

A

OH-

Bonding between biochemical molecules

51
Q

Colour change for iodine test

A

Orange/brown to black

52
Q
A
53
Q
A
54
Q
A
55
Q
A

Biology Module 2 (11 decks)

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