practicals Flashcards
required practical 1- rate of an enzyme controlled reaction- method:
method:
1.make two control samples
- take two flat bottomed tubes
-add 5cm3 of milk suspension to each tube
-add 5cm3 of distilled water to one tube (this control will indicate the absence of enzyme activity)
-add 5cm3 of hydrochloric acid to the other tube (this control indicates the colour of a completely hydrolysed sample)
2.take three test tubes and measure 5cm3 of milk into each, place in water bath at 10°C for 5 minutes to equilibrate.
3.add 5cm3 of trypsin to each test tube simultaneously and start the timer immediately.
4.record how long it takes for the milk samples to completely hydrolyse and become colourless.
5.repeat steps 2-3 at temperatures 20°C, 30°C, 40°C and 50°C.
6.find the mean time for the milk to be hydrolysed at each temperature and use this to work out the rate of reaction.
required practical 1- rate of an enzyme controlled reaction- risk assessment:
required practical 10- investigating simple animal responses:
1.construct a choice chamber using the equipment.
2.to investigate the effect of light intensity on woodlouse movement, cover one half of the lid including the sides with black paper, this will make one side of the chamber dark. put damp filter paper in both sides of the base to make the humidity constant throughout the chamber.
3.place 10 woodlice on the mesh in the centre of the chamber and position the lid on the mesh so its lined up with the base below.
4.after 10 minutes, take off the lid and record the number of woodlice on each side of the chamber, try to minimise the amount of time the lid is off, so that environmental conditions created aren’t disturbed.
5.repeat the experiment after gently moving the woodlice back to the centre. you can use a small, soft paintbrush to help with moving the woodlice if necessary, you should find that most woodlice end up on the dark side of the chamber.
6.to investigate humidity, place some damp filter paper in one side of the base and a desiccating (drying) agent in the other side. don’t cover the lid with paper, put the lid on and leave the chamber for 10 minutes for the environmental conditions to stabilise before carrying out steps 3-5 above.
