My Classroom Material 152 - BIOLOGY JUNCTION

Chromatography of Simulated Plant Pigments

Chromatography of Simulated Plant Pigments

Introduction
This experiment is conducted to investigate the components Plant Pigments separating visibly. There are a couple of different types of components in plant pigments, and they became clearly visible during this lab. The most important and abundant chemical pigment found in plants is chlorophyll. This pigment exists in two forms; chlorophyll a and chlorophyll b. Chlorophyll absorbs two main colors from light quite well. These are blue, and red. The chlorophyll reflects green light very well, however, the two different types of chlorophyll have their maximum absorption at different wavelengths of light. Chlorophyll a, being the main photosynthetic pigment, has a primary purpose to convert light energy to chemical energy used by the plant itself. Chlorophyll b absorbs light in a region of the spectrum apart from the dominant chlorophyll, and transfers the energy it produces to chlorophyll a. Along with chlorophyll b in transferring their energy produced to the dominant chlorophyll, two other pigments that are found in plants are carotenes and xanthophylls, which are orange and yellow respectively. Since chlorophyll is such a dominant pigment in green plants, this domination hides the color of the carotenes and xanthophylls in the leaves. This causes most plant leaves to appear green most of the time. During the autumn, however, the chlorophyll starts to break down, causing the carotenes and xanthophylls to show their bright red, orange and yellow colors.
These brilliant colors can be separated another way. This different technique, known as paper chromatography, separates mixtures in a liquid into individual components. The technique is based on the fact that each substance in a mixture has a specific affinity for a solid surface and a specific solubility in different solvents. By this method, the solid surface is the cellulose fibers in the chromatography paper, and the solvent is the solution that was placed in the bottom of the developing chamber.
This separation takes place through a process of absorption and capillary action. Just a small drop of the mixture, in this case plant pigment to be separated, is placed at the bottom of the strip of chromatography paper. The chromatography paper is then placed in the developing chamber with a solvent, which wicks up the paper, pulling the solvent up the paper by capillary action, and the mixture of pigments is dissolved as the solvent passes over it. The different components of the mixture move upward at different rates. A compound with greater solubility will travel farther than one with less solubility. The pigments then show up as color streaks on the chromatography paper. These substances have formed a pattern called a chromatogram on the chromatography paper.
The Rf values for each pigment is calculated to establish the relative rate of migration for each pigment. This value represents the ratio of the distance a pigment traveled on the chromatogram relative to the distance the solvent front moved. Scientists use the Rf value of a sample to identify the molecule. Any molecule in a given solvent matrix system has a uniquely consistent Rf value. The formula for this value is as follows:

Rf = Distance each pigment traveled ¸ Distance solvent front traveled

Hypothesis
Using paper chromatography, the pigments that give a leaf its color can be separated and observed to determine the Rf value of each pigment and their function during photosynthesis.

Materials
For this experiment the following items are used — one chromatography reaction chamber, one paper chromatography strip, one capillary pipette, a pencil and paper, calculator, ruler, 50 ml beaker, colored pencils, approximately 10 ml of solvent depending on the size of the reaction chamber, scissors, and simulated plant pigment.

Procedure
Use scissors to cut the bottom of the chromatography paper to a tapered end. Measure the strip and cut the length to equal slightly longer than the reaction chamber. Draw a faint pencil line at the bottom of the tapered end and use a capillary pipette to add some simulated plant pigment to this line. Add 5-10 ml of solvent to the reaction chamber. Extend the chromatography strip through the slit in the lids of the reaction chamber and carefully lower the strip into the chamber so the tapered end is in the solvent and the pencil line is above the solvent level. Make sure the strip does not touch the walls of the chamber and do not bump the chamber as the pigments begin to separate. After the pigments have completely separated and the solvent front has reached the top of the chamber, remove the strip and mark the solvent front with a pencil line before it evaporates. Measure and record the distance the solvent and each pigment traveled. Use a calculator to determine the Rf values for each pigment.

Data

Table 1
Band #	Pigment	Color	Migration distance (mm)	Rf value
1	Carotene	Orange	59mm	.94
2	Xanthophyll	Yellow	56mm	.89
3	Chlorophyll a	Light green	29mm	.46
4	Chlorophyll b	Dark green	14mm	.22
Solvent			63mm

Questions
1. Describe what happened to the original spot of simulated plant pigments? The solvent separated the original spot by wicking up the solvent while dissolving the various pigments in the spot.
2. List some other uses of chromatography? Chromatography can be used to separate various mixtures of subtances, liquids and gases.
3. Which of the 4 pigments migrated the furthest and why? carotene ( orange) because it was the most soluble in the solvent
4. Which type of chlorophyll was the most soluble? chlorophyll a
5. Explain why leaves change color in the fall? In Autumn, chlorophyll starts to break down which allows the other brilliant plant pigment colors to show. These pigments include the red, orange, and yellow colors.
6. What is the function of plant pigments in photosynthesis? Plant pigments trap light energy and convert it into chemical energy that can be used by the plant to make glucose or sugar.

Error Analysis
The chromatography paper touched the sides of the chamber during the waiting time which caused the migration to go slightly to the side instead of straight to the top. Also the strip was bent at the top so there could have been a slight error in measuring the migration of the solvent front.

Conclusion
Paper chromatography proved to be an accurate method of separating and observing the various colors of plant pigments. The pigments dissolved in the solvent and migrated upward. The colors were observed and their migration distances measured & recorded. The Rf value of each pigment was determined by dividing its migration by the migration of the solvent. It was determined that 4 pigments were present in the original spot — carotene, xanthophyll, chlorophyll a, and chlorophyll b. Carotene was the most soluble, while chlorophyll b was the least soluble.

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Chemistry Quiz

Name:

Chemistry Quiz

True/False

Indicate whether the sentence or statement is true or false.

The types of particles that are located in the nucleus of an atom are protons and neutrons, and the types of particles that are located in the energy levels surrounding the nucleus are electrons.

The atomic number of carbon is 6, so it must contain 12 electrons.

Most elements are stable if their outermost energy level contains an even number of electrons.

Atoms in a gas move more rapidly than atoms in a liquid or a solid do.

The products of an endergonic chemical reaction possess more energy than the reactants from which they are produced.

The amount of energy needed to cause a chemical reaction to start is called activation energy.

When an enzyme binds with its substrate, the activation energy needed for the chemical reaction to occur is raised.

Enzymes speed up a chemical reaction by increasing the activation energy of the reaction.

Free hydrogen ions can react with water molecules and form a positively charged ion, the hydronium ion.

10.

Buffers can neutralize acids, but they do not affect bases.

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

11.

The smallest particle of matter that can retain the chemical properties of carbon is

a.	a carbon molecule.	c.	a carbon atom.
b.	a carbon macromolecule.	d.	an element.

12.

The bond formed when two atoms share a pair of electrons is called a

a.	hydrogen bond.	c.	covalent bond.
b.	nonpolar bond.	d.	water bond.

13.

Sharing of electrons in the outer energy levels of two atoms

a.	results in ion formation.
b.	occurs in covalent bonds.
c.	only occurs if both are atoms of the same element.
d.	is found only among carbon atoms.

14.

An atom that has gained or lost electrons is called a(n)

a.	molecule.	c.	ion.
b.	nucleon.	d.	element.

15.

Which of the following statements most accurately describes the difference between an ionic bond and a covalent bond?

a.	Atoms held together by ionic bonds separate when placed in water while atoms held together by covalent bonds do not separate in water.
b.	Ionic bonds hold together atoms of two different types, while covalent bonds hold together atoms of the same type.
c.	Electrons are exchanged between atoms held together by an ionic bond, but they are shared between atoms held together by a covalent bond.
d.	Ionic bonds form between atoms that carry opposite charges, while covalent bonds form between uncharged atoms.

16.

A reaction in which the products have less energy than the reactants is

a.	an endergonic reaction.	c.	a filamentous reaction.
b.	an exergonic reaction.	d.	impossible.

17.

Refer to the graph above. Reaction “1” in the graph

a.	is an energy-storing reaction.
b.	requires a greater activation energy than Reaction “2.”
c.	may use the same initial reactant condition needed to form Product “B.”
d.	All of the above

18.

Refer to the graph above. Which of these statements is true regarding the graph?

a.	Reaction “2” occurs faster than Reaction “3” because Reaction “2” requires more energy than Reaction “3.”
b.	The difference in the graphs shown for Reaction “2” and Reaction “3” is due to a difference in the activation energy needed for these reactions.
c.	Reactant “A” contains more energy at the beginning of the reaction than Product “C” has after the reaction.
d.	All of the above

19.

Changing the course or pathway of a chemical reaction so that it requires less activation energy

a.	is a violation of the laws of nature.
b.	requires higher temperatures than those found within cells.
c.	occurs only when reactants are quickly added to the reaction mixture.
d.	is accomplished by the action of catalysts on reactants.

20.

Oxidation-reduction reactions are important in organisms because they

a.	allow the passage of energy from molecule to molecule.
b.	prevent nuclear reactions from occurring.
c.	allow the creation and destruction of energy.
d.	None of the above; oxidation-reduction reactions do not occur in living organisms.

Chromatography Plant Pigments

Chromatography of Plant Pigments

INTRODUCTION:

Chlorophyll often hides the other pigments present in leaves. In Autumn, chlorophyll breaks down, allowing xanthophyll and carotene, and newly made anthocyanin, to show their colors.
The mix of pigments in a leaf may be separated into bands of color by the technique of paper chromatography. Chromatography involves the separation of mixtures into individual components. Chromatography means “color writing.” With this technique the components of a mixture in a liquid medium are separated. The separation takes place by absorption and capillarity. The paper holds the substances by absorption; capillarity pulls the substances up the paper at different rates. Pigments are separated on the paper and show up as colored streaks. The pattern of separated components on the paper is called a chromatogram.

PRELAB PREPARATION:

Gather leaves from several different plants. CAUTION: Avoid poisonous plants. Autumn leaves from deciduous trees are especially interesting. Sort the leaves by kind (maple, etc.) and color. Review a diagram of a plant cell . Find the grana and the chloroplasts of the cell.

MATERIALS:

Safety goggles
Chromatography solvent (92 parts Petroleum ether to 8 parts acetone)
Chromatography paper (or filter paper) about 1 cm x 15 cm
Ethyl alcohol
Fresh spinach
Test tube
Test tube rack
Scissors and Ruler
Fresh leaves of plants
Glass stirring rod
Paper clip
Cork (to fit test tube)
Mortar and pestle
Sand (optional)
10-ml Graduated cylinder

PROCEDURE:

Leaves should be grouped by kind (maple, etc.) and color. Work with a spinach leaf and with one or more other types. CAUTION: Chromatography solvents are flammable and toxic. Have no open flames; maintain good ventilation; avoid inhaling fumes.

1. Cut a strip of filter paper or chromatography paper so that it just fits inside a 15-cm (or larger) test tube. Cut a point at one end. Draw a faint pencil line as shown in figure 1. Bend a paper clip and attach it to a cork stopper. Attach the paper strip so that it hangs inside the tube, as shown. The sides of the strip should not touch the glass.

2. Tear a spinach leaf into pieces about the size of a postage stamp. Put them into a mortar along with a pinch or two of sand to help with grinding. Add about 5 ml ethyl alcohol to the leaf pieces. Crush leaves with the pestle, using a circular motion, until the mixture is finely ground. The liquid in which the leaf pigments are now for paper chromatography dissolved is called the pigment extract.

3. Use a glass rod to touch a drop of the pigment extract to the center of the pencil line on the paper strip. Let it dry. Repeat as many as 20 times, to build up the pigment spot. NOTE: You must let the dot dry after each drop is added. The drying keeps the pigment dot from spreading out too much.

4. Pour 5 ml chromatography solvent into the test tube. Fit the paper and cork assembly inside. Adjust it so that the paper point just touches the solvent (but not the sides of the tube). The pigment dot must be above the level of the solvent. Watch the solvent rise up the paper, carrying and separating the pigments as it goes. At the instant the solvent reaches the top, remove the paper and let it dry. Observe the bands of pigment. The order, from the top, should be carotenes (orange), xanthophylls (yellow), chlorophyll a (yellow-green), chlorophyll b (blue-green), and anthocyanin (red). Identify and label the pigment bands on the dry strip. Write the species of leaf on the strip as well.
Record the species, external color, and chromatogram pigments in the DATA TABLE of your report sheet.

5. Each pigment has an Rf value, the speed at which it moves over the paper compared with the speed of the solvent.

Rf = Distance moved by the pigment / Distance moved by the solvent

Measure the distance in cm from the starting point (pencil line) to the center of each pigment band. Then measure the entire distance traveled by the solvent. Remember, the starting point for the solvent is also the pencil line and the ending point for the solvent is the top edge of the paper. Do the required divisions and record your Rf values in the DATA TABLE of your report sheet.

6. Wash the mortar and pestle thoroughly, using a little alcohol to remove any remaining pigment.

7. Repeat steps 1 through 6 for each species.

DATA TABLE:

Chromatography Data
Leaf Type (species)	External color	Chromatogram Pigments
Colors from the Top	Pigment Names	Rf Values

Chemistry Study Guide BI

Chemistry Study Guide

Give the name & charge for the 3 subatomic particles in an atom.

What is the smallest particle of matter that keeps all the same properties of oxygen?

What is an element?

All matter in the universe is made of what?

Where are electrons found in atoms?

Electrons will move to a higher energy level whenever they absorb what?

If atoms are packed tightly together is the substance a solid, liquid, or gas?

If the outer energy level of an atom is filled with electrons, will it react?

If an atom only has 6 outer electrons, will it gain or lose electrons to form an ionic bond?

If an atom has 2 outer electrons, will it gain or lose electrons to form an ionic bond?

Why is carbon able to form four covalent bonds with other atoms?

Are covalent bonds formed from sharing or transferring electrons between atoms?

Where are the electrons found that are involved in ionic & covalent bonding?

What is an atom called that has lost or gained electrons?

Are ionic bonds formed from sharing or transferring electrons between atoms?

If the products have less energy than the reactants in a chemical reaction, is the reaction endergonic or exergonic?

Has energy been released or absorbed if the products of a reaction have less energy than the reactants?

Chemical reactions drive all of the activities within __________.

Sketch a graph showing an exergonic reaction.

What helps reduce the amount of activation energy required in chemical reactions?

Biological catalysts are called __________.

Cells contain thousands of different enzymes. True or False

Has a molecule been oxidized or reduced when it gains an electron & hydrogen ion?

Oxidation-reduction reactions in organisms allow the passage of _________ from molecule to molecule.

__________ is determined by the number of particles of a substance in a solution.

If a solution is neutral, what is true about its number of hydrogen & hydroxide ions?

If a solution is alkaline or a base, does it have more hydroxide or hydrogen ions?

If a solution has a pH of 11, is it an acid or base?

Solutions with a pH less than 7, would be acids or bases?

_________ in organisms help prevent great changes in pH.

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Chimpanzee Webquest

Life of the Chimpanzee

Introduction | Task | Process | Evaluation | Conclusion

Introduction

Chimpanzees are primates that live in forest regions of Africa. They are genetically very similar to humans, sharing 98% of the same genes. Because of their similarities, Chimpanzees can reveal much about ourselves and how we learn. Chimpanzees have evolved over time to the most sophisticated primates other than humans. They have a very complex social structure, and even know how to use “tools” to make a task easier. In this web quest, you will learn all about chimpanzees, their common connection with humans, and how they have evolved to survive.

Task

Your task is to use the internet to research chimpanzees. After researching, you will use a poster board to make a Venn diagram that outline the similarities and differences of humans and chimpanzees. After making your diagram, you will present it to the class, explaining the similarities. In addition, you will explain what specific characteristics chimps and humans share that allow them to survive. This will be a group project. An illustration of the Venn diagram is shown below. Group A will be human characteristics, group B will be chimpanzee characteristics, and group C will be the shared traits of humans and chimps. Before beginning the process, skip down and read the Evaluation Rubric so you will know what your grade is based on.

Process

First, you will watch and take notes on the video, Jane Goodall’s Wild Chimpanzees. The movie will give you some background knowledge on what scientists know about chimps and their behavior.
After watching the movie, you will choose a partner to help do research on chimpanzees. This research will be used to construct your Venn diagram and to make a presentation ( PowerPoint – 15 slides ) which you and your partner will give to the class.
Use the following links to initially research chimpanzees. If you wish to do your own customized search, use the Google Search Engine and keywords. Hint: to get the most out of research, divide up the responsibilities and have each person research a different aspect of chimpanzees.

Encyclopedia Entry: Chimpanzee

Jane Goodall Institute

Enchanted Learning: Chimpanzees

Save the Chimps: Fact Sheet

During your research, be sure to record any similarities and differences between chimps and humans. After your research is completed, you will consolidate all of your findings into the diagram.
After each group member is done researching, come together as a group and complete your Venn diagram. Remember to include both unique and shared characteristics of humans and chimpanzees. Remember also to include shared adaptations that allow chimps and humans to survive. Write these adaptations below the diagram.
After each group has completed the diagram, you will present your Venn diagram to the class, explaining your findings using a PowerPoint presentation.

Evaluation:

You will be evaluated based on the following rubric: (CLICK HERE FOR PRINTABLE COPY)

Oral Presentation Rubric	Possible Points	Self-Assessment	Teacher Assessment
Complete Venn diagram with unique adaptations listed at bottom.	25
PowerPoint Presentation well-designed and with 15 slides	25
Presentation was well planned and coherent. (Evidence of rehearsal)	10
Poster board (helpful, neat)	10
Teamwork: Every member of group played a role	10
Presentation shows evidence of research on Chimpanzees (good understanding of similarities and differences)	10
Communication Skills (eye contact, posture, clear voice, appropriate volume, transitions between speakers smooth, and all members presented)	10
Total Possible Points	100

Note that half of your grade is based on the completion of the Venn diagram and PowerPoint, while the other half is distributed among different presentation aspects. Teamwork is a part of your grade as well. Make sure that each member plays a role in research and presentation.

Conclusion:

Chimpanzees and Humans are very different in many ways. Humans are much more advanced in thought and practical skills. Yet, there are still many shared characteristics, such as a complex social hierarchy, ability to use “tools”, and communication. These adaptations have allowed both humans and chimpanzees to survive, each in their respective habitat. Understanding chimpanzee behavior can help us understand our own evolution, where we came from, and perhaps where we are going.

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Table 1