Paper 5 Flashcards
Example of a null hypothesis
There is no significant difference between X and Y
Outline a method using X-ray film, to locate radioactive tissue (3)
Obtain section of plant. Cover section with film. Black spots shown position of radioactivity. Compare sections of plants to identify tissue.
How do you make a plant experiment more reliable
Use more leaves and plants
Dependent variable
This is not what you are ultimately trying to find out but what is being measured. For example, if you are using a respirometer it would be distance moved by meniscus and not rate of respiration.
How do you vary the temperature
Use a thermostatically controlled water bath, then give five specific temperatures. The gapes between these temperatures should be constant
Outline how you can use a respirometer to measure the rate of carbon dioxide production (2)
You remove the CO2 absorbent, ie soda lime. The difference between the movement of the meniscus in this respirometer and in the respirometer with the CO2 absorbent will give you the volume of CO2
How do you measure the rate of respiration after using a respirometer per unit mass (3)
Calculate distance volume of O2 by using the formula h x pie x r^2. You then divined volume by the mass of the organism and the time.
Why would you do the t-test?
If the data is continuous
Why might an experiment not be representative
Small sample size, the groups in the samples were a different size. Different numbers of males and females in each group. Do not include the full age range. Does not include people taking medication. Ethnicity
Design an experiment to find the concentration of enzyme in a solution
Dilute the amylase (stock) solution to give a minimum of 5 solutions, you should use simple dilution. Give the concentration of the solutions. Use a control ie denatured enzyme. Measure the brown zone with a ruler. Do the same test but with the solution you are investigating. Plot a calibration curve of known concentrations and use it to determine extract concentration. Use the same volume of amylase in each well, leave for the same amount of time (a day) in an incubator at a set temperature. Use a buffer to keep pH the same. Same volume of agar in petri dish and cover to prevent contamination. Repeat three times and after excluding anomalies divide to get the mean.
Describe an experiment to use a chromatography from the products of two different enzymes
Make chromatograms using the hydrolysed extracts from both enzymes. Count the number of dots and make comparisons. Run all the chromatograms for the same amount of time, the same number of spots should be dabbed on each chromatography paper. Draw a base line with a pencil, use a capillary tube to give the spots. Concentrate the extract by drying between adding spots. Place the chromatography paper into the solvent so that the solvent is below the pencil line. Cover so that the solvent does not evaporate. Dry the chromatography paper before spraying with the dye. Repeat the experiment five times for each enzyme and then after excluding anomalies divide to get the mean for Rf values.
What is meant by standard error
It shows the reliability of the mean
Describe an experiment which shows whether noise effects reaction time taken to catch a ruler (7)
1) Do the test in silent conditions and in noisy conditions
2) To ensure silence have the person wear noise cancelling headphones
3) To ensue constant level of noise have the person listen to the radio at a set volume
4) Test 5 different people
5) Give no warning when the ruler is dropped
6) Drop the ruler from the same starting distance
7) The participants should be of the same age and sex
8) They should use their dominant hand and not be on any medication
9) Do the experiment at the same time of day, they should have good eyesight
10) Three repeats then after excluding anomalies calculate a mean
11) Low risk
When should you use a bar chart
When the data is discontinuous
When should you user the T-test
When you are comparing two means with continuous data
