biology practical skills

Question 1

What does a respirometer?

Answer 1

A device used to measure the rate of respiration of a living organism by measuring the rate respiration of a living organism by measuring the rate of exchange of oxygen and/or carbon dioxide.

Question 2

How can you use a respirometer to record the rate of respiration?

Answer 2

By putting organisms inside a respirometer there will be more respiration and therefore more CO2.
More oxygen is absorbed by the organism causing more food colouring to move down the pipette
You can place KOH or lime water to absorb the CO2 on the lowest layer of the respirometer.

The rate os respiration= Distance moved by food colouring/time .

Question 3

What does Benedict reagent test for and what colour will show a positive test?

Answer 3

Reducing sugars and will produce a brick-red precipitate

Question 4

How can you test for non-reducing sugars?

Answer 4

First boil the non reducing sugar with HCL

Then react with Benedicts solution ,as it is now broken down into glucose, and will produce a brick-red precipitate.

Question 5

What does an iodine solution test for? What is a positive test?

Answer 5

Will react with starch and change colour from yellow to a blue black colour if present.

Question 6

How can you use reagent strips and a colorimeter to test for the presence and concentration of a reducing sugar?

Answer 6

A colorimeter will qualitatively measure the absorbance/transmission by light of a coloured solution.

More concentrated the solution, the more light absorbed and therefore less light is transmitted.