Gently break up macerate with mounted needle, add 1 small drop of orcein ethanoic stain and leave for 2 mins. The optimum conditions for an enzyme to work are those conditions that allow it to work at its fastest rate. Contaminating controls Using wrong species of bacteria for lawn Recommended.
She compared the results from one such study, shown in the following table, with her own Pic 05 i State one similarity and one difference in the conclusions Sam could make about the effect of temperature on Daphnia heart rate, based on these two sets of data.
In her study, Sam attempted to keep the temperature of the various caffeine solutions constant. I turned on the colorimeter and put in the reference test tube as I pressed the R button. Lock and key theory: Place tips into heated HCl for 5mins then repeat process again by placing tips back into acetic alcohol etc.
Beetroots are root vegetables. Try with individual fibres from different plants and different ways of combining fibres eg twists and plaits. Leave the discs in the test tubes for at least 20 minutes. Gently break up macerate with mounted needle, add 1 small drop of orcein ethanoic stain and leave for 2 mins.
Suggest two reasons why the Daphnia heart rate was higher at the end of the investigation compared to the beats per minute at the start.
Place 8 boiling tubes of distilled water into 8 water baths of different temperature. Read off the volume of oxygen gas produced every 10 mins until 3 readings are the same.
Monkeys are commonly used for brain research, dogs are used in behavioural experiments, rabbits and mice are often dissected in laboratories, mice and fruit flies are used in genetic research, etc.
Calibrate using distilled water in a cuvette first then add 2cm3 of beetroot solution from the first temp to a new cuvette. Place 1 disc of each extract in each quadrant of the agar plate, close and tape with hazard tape. Repeat further 2 times and calculate mean result.
Using the same technique, compare the vitamin C contents of different food and drinks. Beaker of trypsin solution1. I began the stop clock as soon as I put the milk into the test tubes to be able to see the rate of reaction in seconds.
Pic 17 i State one similarity and one difference in the conclusions Amir could make about the effect of temperature on permeability of the membrane, based on these two sets of data. Place in distilled water overnight to remove any dye released on preparation.
The independent variable of this experiment is the concentration of the trypsin enzyme as water was added to dilute the enzyme concentration in controlled amounts.
The vitamin C content of each of the vegetables was determined in their raw state and after boiling. A student used this knowledge to estimate the caffeine content of three drinks.
Wrap all tubes in aluminium foil and place in tube holder on sunny window sill. Repeat 3 times for each concentration of yeast solution. Repeat the procedure for the other tubes. Carry out controls with just distilled water on discs. Quickly add peroxide to yeast and attach gas syringe.
The intensity of red coloration absorbance was determined by the colorimeter. The ethanol in each tube had become red and the discs were slightly pink. Initially, she placed one Daphnia in pond water with no caffeine and counted the number of its heart beats in one minute.
Or celery stalks should be left in beaker of coloured water in order for fibres to be easily seen and pulled out. Once fibres removed, connect between 2 clamp stands and gradually add mass in the middle until the fibre snaps. Continue until the blue colour just disappears. Meanwhile label agar plates with date and split into 4 sections.
Remove 1 Daphnia and place in cavity slide. CORE PRACTICAL ONE Describe how the effect of caffeine on heart rate in Daphnia can be investigated practically, and discuss whether there are ethical issues in the use of invertebrates.
Daphnia, the water flea, is a small freshwater crustacean which lacks physiological methods of maintaining a. Oct 05, · Okay since respirometers and habituation haven't come, what are the dependent variables and how do we maintain the independent variables? Also what are the.
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Below is a summary of each one. Name of practical and independent & dependent variables: Effect of caffeine on Daphnia heart rate Independent: caffeine concentration Dependent: heart rate of Daphnia Measuring the /5(9).48506933 as edexcel biology core practical