Separation of Chloroplast Pigments by Paper Chromatography

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Questions and Answers

What is the purpose of boiling the beaker set-ups in a water bath during the pigment extraction process?

To change the color of the leaves

To prevent the alcohol from evaporating

To ensure the leaves are completely devoid of color (correct)

To speed up the pigment extraction process

What is the indicator used to detect the presence of starch during the experiment with iodine solution?

Blue-black color (correct)

Red color

Green color

Yellow color

Why is it important not to boil the alcohol under direct flame during the pigment extraction process?

To prevent the alcohol from boiling over

To maintain the flammability of the alcohol

To avoid burning the leaves

To ensure safety as ethyl alcohol is volatile and flammable (correct)

What is the purpose of comparing the results between exposed and covered areas of the leaves after the iodine solution test?

To observe differences in starch content due to light exposure Signup and view all the answers

Why is it advised to half-fill each test tube with dilute phenol red solution before conducting the experiment related to carbon dioxide availability?

To observe color changes more clearly Signup and view all the answers

What does blowing into test tubes A and B do to the phenol red solution?

Changes its pH Signup and view all the answers

What is the purpose of using paper chromatography in the separation of chloroplast pigments?

To allow the pigments to diffuse through an absorbent material Signup and view all the answers

How can different chlorophyll pigments be identified in paper chromatography?

By their band color and the distance they travel through the chromatogram Signup and view all the answers

What is the significance of the Rf (retention factor) value in paper chromatography?

It can be compared to known standards to identify unknown compounds Signup and view all the answers

Why is it important to weigh the green leaves before pigment extraction?

To ensure equal amounts of leaves are used for accurate results Signup and view all the answers

Which pigment is associated with a yellow-green to olive green band color on the chromatogram?

Chlorophyll B Signup and view all the answers

In pigment extraction, why are the leaves grounded using a pestle?

To release the pigments from the leaves for analysis Signup and view all the answers

What is the purpose of carefully lowering the extract-treated chromatogram into the tank as described in the text?

To prevent the sides of the chromatogram from touching the tank Signup and view all the answers

How does separating fluid aid in separating chloroplast pigments during paper chromatography?

It causes the pigments to migrate at different rates Signup and view all the answers

What is the purpose of measuring the distance from the origin line to the solvent front and to each color band during paper chromatography?

To calculate the Rf values for each pigment Signup and view all the answers

What is the significance of comparing the calculated Rf values with known standards of each pigment in paper chromatography?

To confirm the identity of each separated pigment Signup and view all the answers

What does a high Rf value indicate in paper chromatography when compared to known standards of chloroplast pigments?

The pigment has migrated a long distance on the chromatogram Signup and view all the answers

Why is it important to suspend the chromatogram freely without any sides touching during paper chromatography?

To avoid interference with the movement of solvent and pigments Signup and view all the answers

Study Notes

Chromatography

Chromatography is a method to separate closely related compounds, such as pigments, by allowing the mixture to diffuse through an absorbent called chromatogram.
The different chloroplast pigments can be separated and observed as different color bands on the chromatogram.

Pigment Identification

Pigments can be identified by their band color and distance they travel through the chromatogram.
The Rf (retention factor) value is a ratio that can be calculated and compared to known Rf standards to identify unknown compounds.

Pigment Extraction

5g of green leaves and variegated leaves are weighed and cut into small pieces.
Acetone is used to grind the leaves and release the pigments.

Chromatography Setup

The extract-treated chromatogram is lowered into the tank, with the end immersed in the separating fluid but not reaching the level of the pigment spot.

Pigment Separation

The solvent will move up the strip and carry the pigments with it, separating the chloroplast pigments.
The separated pigments are drawn on the worksheet and labeled each color band by its corresponding pigment.

Rf Values

Rf values are calculated by measuring the distance from the origin line to the solvent front and to the middle section of each color band.
The Rf values are compared to known standards of each pigment for the specific solvent.

Known Rf Values

Carotene: 0.95
Phaeophytin: 0.83
Xanthophyll: 0.71
Chlorophyll a: 0.65
Chlorophyll b: 0.45

Photosynthesis and Pigment Analysis

Photosynthesis can be used to produce biofuel.
Algae pigment analysis can be done through simulation.

Intensity of Light and Wavelength

The intensity of light affects the rate of photosynthesis.
Different wavelengths of light have different effects on photosynthesis.

Carbon Dioxide Requirement for Photosynthesis

Carbon dioxide is a requirement for photosynthesis.
The experiment involves using dilute phenol red solution and healthy Hydrilla sprigs to test the effect of carbon dioxide on photosynthesis.

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Description

Learn how to separate chloroplast pigments using paper chromatography. Observe color changes in test tubes under bright light and record observations in a worksheet. Explore how chromatography can help differentiate closely related compounds like pigments.