Question 18M.3.SL.TZ2.1
| Date | May 2018 | Marks available | [Maximum mark: 5] | Reference code | 18M.3.SL.TZ2.1 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Compare and contrast, Identify, Predict, Suggest | Question number | 1 | Adapted from | N/A |
Chromatography is a technique used to separate the components of a mixture. The photosynthetic pigments from three organisms were separated by thin layer chromatography: spinach (Spinacia oleracea), a red alga (Porphyra) and a brown alga (Fucus).
Identify a pigment found in all three organisms.
[1]
chlorophyll a
OR
β carotene
Compare and contrast absorption spectra and action spectra.
[2]
a. horizontal axis for both is wavelength/colour
OR
«for a chloroplast/cells/leaves/plants extract» they will have the same/similar shape
Marking point a. may be shown with a diagram.
b. an action spectrum shows the rate of photosynthesis «in chloroplasts/cells/leaves/plants» and an absorption spectrum shows the absorption of light
Porphyra also contains phycoerythrin, which is a red pigment.
Suggest a reason for phycoerythrin being absent from the Porphyra chromatogram.
[1]
a. the pigment didn't dissolve / was insoluble when the pigments from the algae were extracted
b. the pigment was not moved by / was insoluble in the solvent used to separate the pigments
Porphyra also contains phycoerythrin, which is a red pigment.
Predict one colour of light that will be absorbed efficiently by phycoerythrin.
[1]
orange/yellow/green/blue/violet