Pracs pt 1 Flashcards

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1
Q

What are reducing sugars?

A

Sugars that can donate an electron to another molecule

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2
Q

What sugars are reducing sugars?

A

All monosaccharides an some disaccharides (e.g. Maltose & Lactose)

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3
Q

Give examples of monosaccharides 3

A

glucose, fructose and galactose

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4
Q

give examples of disaccharides 3

A

Maltose, sucrose and lactose

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5
Q

How do you test for reducing sugars? 3

A

Place 3cm^3 of food solution into boiling tube & 3cm^3 of Benedict’s solution

Place boiling tube into beaker of boiling water

It will go from blue to warmer colour if reducing sugar is present

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6
Q

How to test for non-reducing sugars? 7

A

Add 3cm^3 of food solution into boiling tube

Add 3cm^3 of dilute hydrochloric acid

Gently boil the solution for 5 minutes

Add 3cm^3 of a dilute alkali like sodium hydroxide solution

Use pH paper to check if solution is alkaline

Add 3cm^3 Benedict’s solution and heat in boiling water for 5 minutes

Positive test will show warmer colour change

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7
Q

When would you test for non-reducing sugar?

A

When there is either no reducing sugar or a very small amount

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8
Q

What do you use to test for starch?

A

Iodine solution

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9
Q

How do you test for starch? 2

A

Add drop of iodine to food sample

Solution will turn blue/black if starch is present

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10
Q

What do you use to test for proteins?2

A

Biuret solution, which contains copper(II) sulfate and sodium hydroxide

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11
Q

How do you test for proteins? 3

A

Add drops of sodium hydroxide to each sample

Add drops of copper(II) sulfate solution to each sample

Colour change from blue to lilac if protein present

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12
Q

Draw a table of a simple dilution. You are given 1% concentration of HCL solution, make 5 concentrations of this solution, each with a volume of 10cm^3

A

On layer

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13
Q

Draw a diagram of the simple dilution you made a table of

A

On Layer

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14
Q

Draw a diagram of a serial dilution of 1% HCL solution, reducing by a factor of 10 each time

A

On LAyer

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15
Q

Draw a diagram of a serial dilution of 1% HCL solution, reducing by a half each time

A

On layer

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16
Q

What are the main steps in drawing results tables? 4

A

Units are only in the headings

Independent variable comes first in the table

All results are recorded with the same number of decimal places

Values calculated for mean are recorded to same precision as raw data

17
Q

What are the main steps in drawing line graphs? 4

A

Independent variable is on X axis, dependent on Y

The scale along each axis must be spaced at equal intervals

Scales should cover full range of data plotted on graph

Points should be plotted as crosses, NOT dots

18
Q

What are the main points for a line of best fit? 4

A

Can be smooth, free hand curve OR a straight line drawn with a ruler

Should intersect majority of points

Should have equal number of points on either side of the line

Never continue the line beyond the final point unless asked

19
Q

What do examiners mean when they say “Plot a graph” vs “plot a chart”

A

Graph= line graph
Chart= Bar chart