Chloroplast pigments can be separated and identified by a technique called chromatography. A student carried out an investigation using paper chromatography to separate the pigments in a solution containing two chloroplast pigments.

The results of the investigation are shown in Figure 10.2.

Figure 10.2, a chromatography-paper diagram on gridded paper: a baseline at 0 cm, a solvent-front line at 15 cm labelled 'distance travelled by solvent', a dot at about 14.4 cm labelled 'distance travelled by pigment A', and a lower dot at about 6-7 cm labelled 'distance travelled by pigment B'; the paper itself is labelled 'chromatography paper'.

The

R_{f}

value of pigment A is 0.96. Using Figure 10.2, calculate the

R_{f}

value of pigment B.

R_{f}

value of pigment B

10(b)(ii)Biochemical Tests Laboratory MethodsEasy1 mark

Table 10.1 shows the

R_{f}

values of some photosynthetic pigments.

Table 10.1

Pigment	$R_{f}$ value
Chlorophyll a	0.59–0.68
Chlorophyll b	0.40–0.54
Carotene	0.94–0.98
Xanthophyll	0.15–0.28

Use Table 10.1, together with the

R_{f}

value of pigment A (0.96) and the

R_{f}

value of pigment B calculated in (i), to identify pigment A and pigment B.

Pigment A

Pigment B

10(b)(iii)PhotosynthesisEasy2 marks

Describe the role of pigments A and B in photosynthesis.

Answer

0 words