Interaction & Interdependence C.3 Photosynthesis (id: 420102d71)

本题目来源于试卷: Interaction & Interdependence C.3 Photosynthesis，类别为 IB生物学

[单选题]
Thin-layer chromatography can be u. n-ek9 .4p9vqo; wgb:avmimrs7 f9saqoxm1fld;, zj2 ed to separate photosynthetic pigments. Below is a diagram showing the sejdq f91sz7aml xo 2;,fparation of pigments in this way. Rf values are used to work out what pigments are present in the leaf extracts.
Which of the following are the measurements that need to be taken to calculate the Rf values?

A. From the pencil line to the solvent front and from the pencil line to the centre of each pigment spot
B. From the centre of the pigment spot to the solvent front and from the base of the chromatography plate to the centre of the pigment spot
C. From the top of the pigment spot to the solvent front and from the bottom of the pigment spot to the pencil line
D. From the bottom of the chromatography plate to the centre of the pigment spot and from the bottom of the chromatography plate to the solvent front


参考答案:  A


本题详细解析:
A

For thin-layer chromatography, the Rf value of a substance is the ratio of the distance the substance travels to the distance the solvent travels on the TLC plate. Therefore you need to measure the distance between the pencil line and the solvent front and the distance between the pencil line and the centre of each pigment spot. By taking these measurements, you can calculate the Rf value for each pigment spot. Therefore Choice A is correct.

Choices B, C and D are not the correct measurements for calculating Rf values.

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