Statistical Tests and Practicals

Question 1

When do you use T tests?

Answer 1

When you are testing two different MEANS

Question 2

How do you produce a calibration curve?

Answer 2

Would have created solutions of known and different concentrations
Would placed solutions in colorimeter and tested for the colorimetry colour/absorbance
Plotted these results on a calibration curve
Using the calibration curve, they would find the concentrations using the absorbance values

Question 3

Why when using an optical microscope must the specimen be thin?

Answer 3

so you can get only a single layer of cells so light can pass through
Thus you will be able to see the internal structure of the cells

Question 4

Test for reducing sugars

Answer 4

Add Benedicts reagent to sample and place in water bath, if it goes brick red then a reducing sugar is present

Question 5

When answering a evaluative question on an investigation what are some things to consider?

Answer 5

Sample size
How long the experiment was carried out for
Statistical tests
Side effects
Who the experiment was carried out on
you must consider both sides of the argument

Question 6

Describe process of cell fractionation and ultracentrifugation?

Answer 6

1. sample of cells is homogenised in a blender
2. sample is filtered to remove cell debris
3. isotonic solution-to prevent damage to organelles due to osmotic pressure
4. cold solution- to reduce enzyme activity
5. buffered solution- to prevent pH fluctuation so enzyme doesn’t denature
6. centrifuge at a lower speed to allow nuclei pellet to form at a bottom
7. for other pellets spin at a higher speed