RP 1-6 Flashcards
What is the aim of RP1?
Factor affecting the rate if enzyme controlled reactions
What are the control variables in RP1?
Controlling all other factors that don’t include the one you are investigating
- Temperature, pH, Enzyme concentration, substrate concentration, conc of inhibitors
In RP1, a student controlled the temperature. State two other variables that the should have controlled
Concentration of amylase and pH
Describe how the temperature could have been monitored - RP1
The use of a thermometer in a water bath and check the temperature every 10 minutes to make sure it remains constant
The student maintained the temperature at 30 degrees, why may it be faster at 40 degrees - RP1
The starch and amylase have more kinetic energy at higher temperatures so there are more successful collisions and so more E-S complexes will be formed
The student took samples until the blue-black colour no longer appeared. How would the student ensure it remained consistent - RP1
She could have compared the colour of each sample to the colour of the reaction mixture that has gone to completion and been tested with iodine solution
The student concluded that the optimum ph was 5, explain why this may not be valid? - RP1
The student needs to repeat the experiment using smaller intermediary values. This may include pH 4 to pH 6
What is the aim of RP2?
Preparing and observing a root tip squash
How do you calculate the mitotic index?
Number of cells undergoing mitosis/Total number of cells
What are the control variables - RP2
- The same root tip being use
- The same age root tip
- The same length of root tip
How to use a microscope - RP2
- Select the smallest objective lens
- Place your slide on the stage
- Use the coarse focus to either raise the stage or lower the lense
- Look through the eyepiece lens
Adjust with fine focus
How to calibrate the eyepiece graticule?
- Place a stage micrometer on the stage of a microscope
- Align the scales of the eyepiece graticule and determine how many eyepiece graticules go into one stage micrometre
Explain why the student added a drop of stain - RP2
The stain binds to the chromosomes, so the become visible
Explain why the cover slip was pressed down firmly - RP2
To squash the root tip into a thin layer so that the light could pass through the sample
Explain why the student handled the hydrochloric acid with caution - RP2
Highly concentrated which can be highly corrosive
What is the aim of RP3?
Using a calibration curve to estimate the water potential
What are the control variables - RP3?
- Temperature
- Source of the plant tissue
- Size and shape of the plant tissue
- Batch of stock solution
- Length of time the plant tissue is immersed in the solution
Suggest why the student removed the ‘skin’ of the potato? - Rp3
The skin is a different tissue from the rest of the potato and so has a different water potential
Why did the student use potato chips from the same potato? - RP3
If the potato chips are from the same potato, all the cells will have the same water potential
Suggest why the student processed her data to find the percentage change in mass - RP3?
The initial mass of the potato chips was different, so working out the percentage change would allow her to make a valid comparison
Explain how the student could use her processed data to find the water potential - RP3
- Plot a graph with concentration on the x-axis and percentage change in mass on the y-axis
- Find concentration where curve crosses the x-axis / where percentage change is zero
- Use (another) resource to find water potential of sucrose concentration (where curve crosses x-axis)
What is the aim of RP4?
Factors affecting the membrane permeability
What are the control variables in RP4?
- Source of the plant
- Time in the solution
- Size and shape of the plant tissue
What are the 2 measures to determine the permeability of a membrane?
- Producing colour standards
- Colorimeter
