Biology Practical RP8

Question 1

Pigments

Answer 1

Thylakoid membranes contain many of these to absorb light waves of different frequencies

Question 2

What wavelengths of light are usually absorbed by pigments?

Answer 2

Red and blue
NOT GREEN because green light is reflected

Question 3

Why is it important to have a large variety of pigments that absorb different wavelengths of light?

Answer 3

Because a higher proportion of light is absorbed to increase rate of photosynthesis

Question 4

What is the point of this practical?

Answer 4

To separate the different pigments present in a leaf dependent on their solubility then identifying them by calculating their Rf value and comparing this value to data booklet value

Question 5

Why should we use pencil to draw the ink line and solvent front?

Answer 5

Because if we used ink, ink would mix with the pigments
And with ink the origin line would move positions, with pencil it is at the same position

Question 6

Overall method

Answer 6

Chromatography paper: draw origin line with sample of leaf pigments dotted + solvent front line
Place so tip is in solvent so solvent travels up paper
Take out once solvent travels up paper and dissolves all pigment+ reached solvent front line

Question 7

Rf value

Answer 7

Distance travelled by pigment
Divided by
Distance travelled by organic solvent (distance from origin to solvent front)

Question 8

More soluble pigments…

Answer 8

Runs faster = travels up solvent faster to solvent front = larger Rf value calculated