Required Practicals

Question 1

2: investigating mitosis

Answer 1

Scalpel - cut root tip
Test tube - HCl - 60C 5min
Rinse distilled and dry
Microscope slide
Cut 2mm off tip
Mounted needle - cut open root - spread cells thinly
Stain drops - visible chromosomes
Place cover slip - squash firmly
Look under microscope

Question 2

2: Using optical microscope

Answer 2

Clip slide onto stage
Select lowest powered objective lens
Coarse object lens - brings obj lens closer to slide
Look through ocular lens and focus using fine adjustment knob

Question 3

2: What is the equation for mitotic index?

Answer 3

Mitotic index =

Total no of cells observed

Question 4

3: water potential - measuring change in mass

Answer 4

Cut potato equally - cork borer
Weigh - mass balance
Sucrose solution - serial dilution
Place potato in solution - 20 min - stopwatch
Dry and reweigh
Calculate percentage lost of mass

Question 5

4: cell membrane permeability

Answer 5

Cut 5 equal beetroot. Rinse pigment - scalpel
5 test tubes 5cm3 water 10-50C preheat
Place beetroot in test tube for 5 min
Remove beetroot
Colorimeter - passes specific wavelength of light through substance and measures absorbance
Turn on and allow 5 min to stabilize
Distilled water in cuvette
Sample of pigment in cuvette - pipette
Cuvette in colorimeter - not Frosted sides
Repeat

Question 6

4: what does a higher reading on the colorimeter mean?

Answer 6

Higher absorbance so more pigment so higher permeability

Question 7

6: what is antibiotics a type of?

Answer 7

They are a type of anti microbial substance

Question 8

6: aseptic techniques

Answer 8

Disinfect surfaces before starting
Work near Bunsen flame
Sterilize glassware before and after use

Question 9

6: testing effects of antibiotics

Answer 9

Bacteria grown in liquid broth
Sterilize inoculating loop - Bunsen flame
Transfer bacteria to ajar plate and spread bacteria across it - loop
Place sterile paper discs containing diff antibiotics. Control with water only
Seal - tape, invert & incubate @ 25C for 48h
Inhibition zones form - larger zone = more bacteria inhibited from growing

Question 10

1: rate of enzyme controlled reaction - measuring volume and time of gas produced

Answer 10

Set up apparatus with boiling tubes of same vol and conc - add buffer to maintain ph
Waterbaths - 10-50C
Place test tubes and enzyme test tubes
Add same vol and conc of enzyme to each solution - quickly attach to bung
Time 60s of 02 produced
Divide mass of o2 prod by 60s to get rate of enzyme controlled reaction