Observing mitosis

Question 1

What is a general summary of the investigation?`

Answer 1

Chromosomes are stained blue using orcein ethanoic stain so mitosis can be observed

Question 2

Equipment needed.

Answer 2

• garlic roots
• sharp knife
• 1M hydrochloric acid (1M means moles per litre basically it just indicates a specific concentration0
• ethanoic acid
• orcein ethanoic stain
• ice-cold distilled water
• water bath at 60 degrees celcius

Question 3

Method.

Answer 3

1. place test tube of 2cm3 1M hydrochloric acid (HCL)
2. cut off 1-2cm of root tip from garlic
3. put in a test tuse containing 2cm3 of acetic alcohol for at least 12 mins
4. remove and place in another test tube containing 5cm3 of ice cold distilled water
5. leave fr 4-5 minutes then remove and dry
6. place tips into heated HCL for 5 mins
7. repeat 3-6 again
8. transfer tip to microscope slide and cut 4-5mm from the growing tip
9. gently macerate (break up) the tip with mounted needle
10. add one small drop of orcein ethanoic stain and leave for 2 mins
11. add coverslip and blot with filter paper
12. view under microscope and identify the stages of mitosis

Question 4

What volume of hydrochloric acid is needed?

Answer 4

2cm3

Question 5

What volume of acetic acid is needed?

Answer 5

2cm3

Question 6

What volume of distilled water is needed?

Answer 6

5cm3

Question 7

How long should the sample be before the second chop?

Answer 7

1-2cm

Question 8

How much of the root tip is actually used under the microscope?

Answer 8

4-5mm

Question 9

How long should the root tip be in the acetic alcohol for?

Answer 9

at least 12 minutes

Question 10

How long should the root tip be in the distilled water for?

Answer 10

4-5 mins

Question 11

How long should the root tips be in the hydrochloric acid for and at which temperature?

Answer 11

5 mins at 60 degrees

Question 12

What is the name of the stain?

Answer 12

orcein ethanoic stain

Question 13

Possible evaluation issues?

Answer 13

• resolution of microscope
• human error in counting number of cells
• enough time in solutions