Practical info last Flashcards
(11 cards)
What is the dependent variable
- What is being measured
What is the independent variable
- What you are changing
What is the control variable
- What is kept the same
For measuring enzyme activity what are the variables?
- Independent (temperature/ph/light intensity - whatever you are measuring)
- Depedent (Rate of reaction)
- Control (The factors within the experiment that you must keep the same for validity)
Method for Rate of reaction practical..
Add enzyme solution to a boiling tube.
Add substrate (H₂O₂) and quickly seal with bung connected to a gas syringe.
Measure volume of O₂ released every 10 seconds.
Repeat with different temperatures, pH or concentrations.
Keep other variables constant.
Plot rate of reaction against independent variable.
What is mitotic index?
- Number of cells undergoing mitosis/total number of cells X 100
Method for mitotic index practical…
Cut 1–2 cm root tip (e.g. onion).
Soften tissue in HCl at 60°C for 5 min.
Place on slide, stain (e.g. with acetic orcein or toluidine blue).
Cover with coverslip and gently squash.
View under light microscope, identify mitosis stages.
Count cells in each stage; calculate mitotic index.
Method for dissection
Use dissecting scissors/scalpel carefully.
Identify and observe structures (e.g. alveoli, valves, gill filaments).
Follow ethical guidelines; wear gloves and disinfect tools.
Label diagram or photo.
Why are colourimeters used?
- colorimeters are used to give accurate, quantitative measurements of solutions where a colour change indicates the concentration of a substance or the extent of a reaction.
What is a calibration curve?
A calibration curve is a graph that shows the relationship between a known concentration of a substance and a measured value, usually from a colorimeter (like absorbance or transmittance).
