mitosis practical

Question 1

detailed method

Answer 1

• cut off root tip off onion/garlic and add to beaker of 10ml hydrochloric acid
• leave in for 10 mins
• rinse the root tip in distilled water
• place specimen on microscope slide
• cover specimen with toluidene bleu stain and macerate with mounted needle to separate cells
• add cover slip and spread material gently
• look through microscope
• chromosomes should stain dark blue
• take a photo of sample
• calculate mitotic index

Question 2

why are you told to observe cells that are found at or just behind the root tip called the meristem

Answer 2

most ideal area to look for mitosis, meristem cells are undifferentiated, and constantly dividing, making them ideal to observe.
cells in meristem are totipotent

Question 3

explain why cells may appear elongated with no visible chromosomes if they are taken too far along the root

Answer 3

in the region of cell elongation, they are increasing in size but not dividing

Question 4

why use HCL

Answer 4

-HCL quickly denatured any protein including enzymes
- it quickly stops cellular processes
- kills cells halting the process immediately so the cells in different stages can be seen

Question 5

why use toluidine blue

Answer 5

Dye is used for staining of acid rich tissues
As it can be absorbed by nucleic acid
- it increases contrast
- makes chromosomes visible

Question 6

why is it necessary to spread the material on the slide

Answer 6

cells could overlap each other
stain might not have been dispersed properly

Question 7

why is it suggested to look at several fields of view

Answer 7

-comparison
-mean of mitotic index

Question 8

what does diploid number of 16 mean

Answer 8

-8 chromosomes from male
-8 from female