required prac 2 Flashcards
1
Q
why use hydrochloric acid
A
to soften and loosen the root
2
Q
why use acetic orcein stain
A
to turn the chromosomes a purple-red colour so that they are visible
3
Q
why use a mounted needle
A
to lower the cover slip and prevent any bubbles underneath it
4
Q
why use root tip
A
this is the growing region and will be where mitosis is occuring
5
Q
method
A
- grow onion/garlic in dark for 3 days over beaker of water, to grow new roots
- use scalpel cut off 5mm root tip
- put in test tube with HCL into water bath 60c 10 mins, soften cells
- poor out acid, place on watch glass, rinse distilled water, place on microscope slide and use filter paper to remove any excess water
- two drops of acetic orcein stain then used the mounted needle to lower the coverslip and leave for 10 mins so stain works
- place filter paper on top and gently press so cells spread out and are only one cell thick so light can pass through
6
Q
risk of scalpel
A
cut yourself
cut on white tile and away from yourself
7
Q
risk hydrochloric acid
A
irritant
wear goggles and wash hands if in contact with skin
8
Q
mitotic index
A
no. of cells in mitosis/ total no. cells time by 100
