Year 1 Bio Required Practicals

CATALASE CATALYSES HYDROGEN PEROXIDE INTO WATER AND OXYGEN.

THE VOLUME OF OXYGEN RELEASED OVER A PERIOD OF TIME AT VARYING TEMPERATURES.

 How the experiment is carried out:

• Boiling tubes set up containing same volume of H2O2.
• Rest of the apparatus set up as shown in diagram.
• Each boiling tube put in a water bath at different temperatures (10-50 degrees celsius at 10 degree intervals) along with other a seperate boiling tube containing the catalase. Allow to heat up to desired temperature.
• Use a pipette to add the same volume and concentration and catalase to each boiling tube and quickly add the bung and delivery tube.
• Use a stopwatch to record the volume of oxygen produced in a minute.
• Repeat the experiment at each temperature and form a mean volume of oxygen produced at each temperature.

 (Ignore reference to mang-oxide)

USED TO OBSERVE STAGES OF MITOSIS IN THE ROOT TIP

MITOTIC INDEX = NUMBER OF CELLS WITH VISIBLE CHROMOSOMES/TOTAL NUMBER                                                                                                              OF OBSERVED CELLS

 How the experiment is carried out:

• Put on lab coats and eye protection
• Add 20cm^3 1M HCl to a boiling tube and put in water bath at 60 degrees celsius
• Use a scalpel to cut 1cm from the tip of the growing root and transfer to the boiling tube
• Incubate for 5 minutes
• Use tweezers to remove the tip and rinse with cold water then allow to dry
• Cut 2mm from the end and place the tip on a microscope slide
• Use a mounted needle to break open the tip and spread the cells out thinly
• Add a few drops of a stain (to make cells more obvious) 
• Place a cover slip over and squash the tissue (to allow light to pass through)
• Observe through an optical lightscope
• Work out mitotic index

MAKING 5 SERIAL DILUTIONS OF A SUCROSE SOLUTION WITH AN INITIAL SUCROSE CONCENTRATION OF 2M, BY A SCALE FACTOR 2

How to carry out the experiment:

• Line up 5 test tubes in a rack
• Add 10cm^3 of 2M sucrose solution to the first test tube and 5cm^3 of distiled water to the other 4 test tubes
• Use a pipette to draw 5cm^3 of the solution from the 1st test tube and add it to the 2nd test tube and mix thoroughly
• Repeat this experiment 3 more times to create 0.5M, 0.25M and 0.125M solutions respectively

How the experiment is carried out:

• Wear a lab coat and eye protection
• Lay lungs on a cutting board
• Inflate lungs with tube and a hand pump
• Cut down the trachea not covered by the C-shape cartilage
• Continue by cutting down one of the bronchi
• Cut off a piece of the lung, noticing the spongey feel caused by the trapped air
• Dispose of the lungs and disinfect surfaces before washing your hands with soap and hot water

ANTIBIOTICS ARE ANTIMICROBIAL SUBSTANCES WHICH CAN BE TESTED ON TYPES OF BACTERIA PROVIDING ASEPTIC TECHNIQUES ARE CARRIED OUT

How the experiment is carried out:

• Sterilise a wire innoculation hoop over a Bunsen Burner and use it to transfer the bacteria from the broth to the agar plate containing agar jelly, spreading the bacteria around the plate with the hoop.
• Place several sterile paper discs soaked with different antibiotics around the plate and a control group with no antibiotic
• Tape the lid of the agar plate on and incubate the plate at 25 degress celcius for 48 hours
• Anywhere the bacteria cannot grow is an inhibition zone and tells you how effective an antibiotic is and at what concentration

Actual aseptic techniques include:

• Disinfecting work surface before and after the experiment
• Work near a Bunsen Burner, the rising of the hot air will carry airbound microbes away from the agar plate
• Sterilise the wire innoculation hoop before and after each use by passing it through the bunsen burner for 5 seconds
• Flaming the neck of the broth container after its opened and before it's closed, causing air to move out of the container
• Sterilise all glassware before and after use (in an autoclave)