Practical

Question 1

How many data points are needed

Answer 1

More than 5/ 5 or more

Question 2

How many repeats at each data point

Answer 2

3 repeats

Question 3

What is placed in a colorimeter

Answer 3

Curettes

Question 4

List ways to keep agar plate sterile

Answer 4

Wipe surfaces
Bunsen burner in the corner
Flame inoculating loop
Flame bottle neck
Close bacterial bottle and Petri dish
Close doors and windows

Question 5

Why are buffers added

Answer 5

To ensure nothing except the dependant variable changes

Question 6

Rf value =

Answer 6

Rf value = distance of pigment
————————
Solvent front

Question 7

Same substance has

Answer 7

The same Rf value. It is standardised

Question 8

Volatile substances are

Answer 8

Flammable

Question 9

Controls for DCPIP questions

Answer 9

1 - just DCPIP
2 - just chloroplast
3 - DCPIP, chloroplasts in the dark

Question 10

Positive result for DCPIP experiment

Answer 10

Blue / green to green

When DCPIP is reduced it goes blue to colourless)

Question 11

What does ammonium hydroxide do

Answer 11

Interferes with redox reactions in the slowing down of the colour change as it competes with DCPIP for electrons