Category: My Classroom Material

Diffusion Quiz

Name: 

Homeostasis & Transport

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
Diffusion is an active process that requires a cell to expend a great deal of energy.
2.
A concentration gradient is the difference in concentrations of a substance across space.
3.
A solution outside a cell is hypotonic if its concentration of solute  molecules is lower than the
concentration of the solute molecules inside the cell.
4.
Homeostasis is the process by which molecules move toward an area of lesser concentration.
5.
Facilitated diffusion is an active form of carrier transport.
6.
The sodium-potassium pump moves sodium ions into the cell and potassium ions out of the cell.
7.
Wastes may exit a cell by pinocytosis.
8.
Ion channels are usually able to transport only one type of ion.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
9.
A cell membrane consists of phospholipids and different large molecules of
a.
protein.
c.
DNA.
b.
fat.
d.
carbohydrates.
10.
The outer surface of a cell membrane is:
a.
hydrophobic
c.
hydrophilic
b.
isotonic
d.
hypertonic
11.
Which of the following is an example of osmosis?
a.
the movement of ions from an area of greater concentration to one of  lesser concentration
b.
the movement of ions from an area of lesser concentration to one of greater concentration
c.
the movement of water through a membrane from an area of greater concentration to one of  lesser concentration
d.
the movement of water through a membrane from an area of lesser concentration to one of greater concentration
12.
Pinocytosis and phagocytosis are both examples of:
a.
plasmolysis
c.
exocytosis
b.
cytolysis
d.
endocytosis
13.
Some plants absorb mineral ions from the soil even though the soil concentration is lower than the internal cell concentration. This is due to:
a.
cytolysis
c.
diffusion
b.
active transport
d.
passive transport
14.
The pouch formed during endocytosis is called a:
a.
gate
c.
vesicle
b.
contractile vacuole
d.
channel
15.
A process that requires the addition of energy is
a.
osmosis.
c.
diffusion.
b.
active transport.
d.
facilitated diffusion.
16.
If two substances of different concentrations are present on either side of a semipermeable membrane, the substances move
a.
away from the area of lower concentration.
b.
toward the area of lower concentration.
c.
until equilibrium is reached.
d.
until all molecular motion ceases.
17.
The following are steps that occur during endocytosis.  Which is the first step that is out of order.
a.
material is taken into the cell by infolding of cell membrane
b.
the infolding forms a pocket
c.
the pocket forms a vacuole in the cytoplasm
d.
the pocket breaks loose from the cell membrane
18.
Na+ ions are transported across cell membranes of body cells by
a.
molecular pumps.
c.
simple diffusion.
b.
facilitated diffusion.
d.
passive transport.
19.
The process by which molecules of a substance move from an area of higher concentration of that substance to an area of lower concentration is known as
a.
exocytosis.
c.
endocytosis.
b.
pinocytosis.
d.
diffusion.
            Concentration of Water and Solutes in Four Adjacent Cells
            chp5_web_tutorial_files/i0220000.jpg
20.
Refer to the illustration above. In this system, solute molecules in cell “B” are most likely to
a.
remain in cell “B.”
c.
diffuse into cell “A.”
b.
adhere to cell “B’s” membrane.
d.
diffuse into cell “D”
21.
Refer to the illustration above. In this system, water molecules are most likely to diffuse in which direction?
a.
from “A” to “B”
c.
from “D” to “C”
b.
from “B” to “D”
d.
from “C” to “A”
22.
The dispersal of ink in a beaker of water is an example of
a.
diffusion.
c.
active transport.
b.
osmosis.
d.
endocytosis.
23.
Which of the following enters a cell by active transport?
a.
glucose
c.
sodium ion
b.
water
d.
potassium ion
24.
endocytosis : exocytosis ::
a.
phagocytosis : bacteria
c.
cold : hot
b.
secrete : exocytosis
d.
white blood cell : bacteria
25.
Glucose enters a cell most rapidly by
a.
facilitated diffusion
c.
osmosis
b.
diffusion
d.
phagocytosis
26.
When the cells in a plant have low turgor pressure, the plant
a.
is rigid
c.
wilts
b.
dies
d.
explodes

 
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Cell Reproduction Quiz

Name: 

Cell Reproduction

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
DNA replicates during interphase
2.
Chromatids separate from each other during telophase.
3.
Four sperm are produced from each cell undergoing meiosis in a male.
4.
Chromatin appears as tightly coiled, rod-shaped structures in the cell nucleus.
5.
Each homologue of a chromosome pair has a different size and shape.
6.
Meiosis produces diploid cells.
7.
Sperm and egg cells contain only one member of each homologous pair of chromosomes
8.
The information needed by a cell to direct its activities and to determine its characteristics is contained in molecules of deoxyribonucleic acid (DNA).
9.
Meiosis is identical to mitosis except for the kind of cells in which it occurs
10.
Variation promotes a better chance for survival should change in the environment occur.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
11.
During anaphase I of meiosis
a.
one chromatid of each chromosome is pulled to each pole
b.
one pair of chromatids of each tetrad is pulled to each pole
c.
a tetrad is pulled to each pole
d.
centromeres are split
12.
This process results in the production of diploid cells.
a.
mitosis
c.
spermatogenesis
b.
meiosis
d.
oogenesis
13.
Which does not occur during mitosis in an animal cell?
a.
Asters form during metaphase.
c.
Centrioles separate during prophase.
b.
Sister chromatids split during telophase.
d.
Telophase overlaps cytokinesis.
14.
A certain cell contains the following chromosomes F and F*; G and G*; the possible combinations of these chromosomes in the gametes of this organism are
a.
FF*, F*F*,FF*,F*F*
c.
FG,GG,FF*,G*G
b.
FF,FF*,GG*,F*G*
d.
FG,FG*,F*G,F*G*
15.
During cell division, the cytoplasm divides to become two new cells during
a.
synthesis.
c.
telophase.
b.
anaphase.
d.
cytokinesis.
16.
Each pair of chromatids is attached at an area called the
a.
chromatid.
c.
chromatin.
b.
centromere.
d.
cytokinesis.
17.
Which cells in the normal human body rarely undergo cell division?
a.
skin
c.
digestive tract
b.
bones
d.
nerves
18.
The DNA of chromosomes is coiled around special proteins called
a.
nucleosomes.
c.
histones.
b.
chromatids.
d.
chromatin.
19.
Separation of homologues occurs during
a.
mitosis.
c.
meiosis II.
b.
meiosis I.
d.
fertilization.
20.
crossing over : genetic variation::
a.
dividing squares : circles
c.
stacking pennies : disorder
b.
card shuffling : new combinations
d.
measuring lines : lack of exactness
21.
Two nuclei are produced during
a.
mitosis only
c.
both mitosis and meiosis
b.
meiosis only
d.
neither mitosis nor meiosis
22.
The two main stages of cell division are called
a.
mitosis and interphase.
b.
synthesis and cytokinesis.
c.
the M phase and the S phase.
d.
cytokinesis and mitosis.
23.
Fertilization produces a
a.
monoploid zygote
c.
monoploid sperm
b.
diploid zygote
d.
diploid ovum
24.
What is responsible for growth by increasing cell number?
a.
mitosis only
c.
both mitosis and meiosis
b.
meiosis only
d.
neither mitosis nor meiosis
25.
In order to fit within a cell, DNA becomes more compact by
a.
breaking apart into separate genes.
b.
extending to form very long, thin molecules.
c.
wrapping tightly around associated proteins.
d.
being enzymatically changed into a protein.
26.
The genetic information in a cell is contained in the
a.
nucleus
c.
Golgi bodies
b.
ribosomes
d.
chloroplasts
27.
The thread-like structure that helps move the chromosomes apart during mitosis is called the
a.
centriole.
c.
aster.
b.
spindle.
d.
nucleosome.
28.
growth : G ::
a.
mitosis : C
c.
cytokinesis : M
b.
mitosis : meiosis
d.
DNA copying : S
29.
Human cells with 26 chromosomes are produced during
a.
mitosis only
c.
both mitosis and meiosis
b.
meiosis only
d.
neither mitosis nor meiosis
30.
During crossing-over, portions of the chromatids
a.
replicate their DNA
c.
exchange their genes
b.
double their length
d.
uncoil their proteins
31.
As a result of mitosis in a human body cell, the nucleus of each daughter cell contains
a.
92 chromosomes.
c.
23 chromosomes.
b.
46 chromosomes.
d.
64 chromosomes.
32.
One difference between cell division in plant cells and in animal cells is that plant cells have
a.
centrioles.
b.
centromeres.
c.
a cell plate.
d.
chromatin.
33.
When during the cell cycle are chromosomes visible?
a.
only during interphase
b.
only when they are being replicated
c.
only during cell division
d.
only during the G1 phase
34.
Which of the following is NOT a correct statement about the events of the cell cycle?
a.
Interphase is usually the longest phase.
b.
DNA replicates during the S phase.
c.
Cell division ends with cytokinesis.
d.
The cell grows only occurs during the G2 phase.
35.
female : XX::
a.
female : gametes
c.
male : YY
b.
female : eggs
d.
male : XY
36.
In cell division, chromatin material becomes
a.
asters
c.
nucleoli
b.
microtubules
d.
chromosomes
37.
A student can study a karyotype to learn about the
a.
molecular structure of a chromosome.
b.
genes that are present in a particular strand of DNA.
c.
medical history of an individual.
d.
chromosomes present in a somatic cell.
38.
What is the role of the spindle during mitosis?
a.
It helps separate the chromosomes.
b.
It breaks down the nuclear membrane.
c.
It duplicates the DNA.
d.
It divides the cell in half.
39.
Meiosis I is often called “reduction division” because
a.
chromosomes gain electrons and hydrogen atoms.
b.
gametes are much smaller than the cells from which they are produced.
c.
the number of cells is reduced from four to two.
d.
diploid cells divide to become haploid cells.
40.
The process by which a cell divides into two daughter cells is called
a.
cell division.
b.
metaphase.
c.
interphase.
d.
mitosis.

 
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Ecosystem Quiz

Name: 

 

 

 

 

 

 

 

Ecosystem Interactions

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
Freshwater habitats are independent of terrestrial habitats.
2.
An ecosystem consists of biotic and abiotic factors.
3.
Clearing a forest would reduce the amount of energy available to the consumers.
4.
While an understanding of the interactions between organisms and their environment was very important to early hunter and gatherer humans, it is even more important today because humans are having significant effects on the environment.
5.
Cutting down trees in a forest alters the habitat of the organisms living in the forest.
6.
An organism’s niche includes its habitat.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
7.
Abiotic factors affect an ecosystem by all of these except the
a.
quantity and quality of water
c.
nitrogen-fixing bacteria
b.
amount of light available
d.
quantity of minerals
8.
The most important single factor affecting the biosphere is
a.
solar radiation
c.
precipitation
b.
the biotic community
d.
wind
9.
Which of the following is the smallest ecological unit?
a.
a community
c.
a population
b.
a biome
d.
an ecosystem
10.
Collectively, physical factors such as light, temperature, and moisture that affect an organism’s life and survival are called the
a.
biotic environment
c.
ecosystem
b.
abiotic environment
d.
niche
11.
The rate of photosynthesis carried on by plants living in a body of water depends upon the
a.
oxygen content of the water
c.
amount of light that penetrates the water
b.
nitrogen content of the water
d.
elevation of the body of water
12.
Which of the following would not be included in a description of an organism’s niche?
a.
its trophic level
c.
its color
b.
the humidity it prefers
d.
when it reproduces
13.
Ecology is the study of the interaction of living organisms
a.
with each other and their habitat.
b.
and their communities.
c.
with each other and their physical environment.
d.
and the food they eat.
14.
The destruction of the ozone layer may be responsible for an increase in
a.
cataracts.
c.
cancer of the retina.
b.
melanoma.
d.
All of the above
15.
Ozone in the atmosphere
a.
leads to formation of acid precipitation.
b.
combines readily with water vapor.
c.
absorbs harmful radiation from the sun.
d.
All of the above
16.
Ecological models are useful for
a.
making predictions about future ecological changes.
b.
testing predictions about future ecological changes.
c.
evaluating proposed solutions to environmental problems.
d.
All of the above
17.
The physical location of an ecosystem in which a given species lives is called a
a.
habitat.
c.
community.
b.
tropical level.
d.
food zone.
18.
Which of the following is not an adaptation for avoiding unfavorable conditions?
a.
acclimation
c.
dormancy
b.
body temperature regulation
d.
migration
19.
Which of the following would not be included in a description of an organism’s niche?
a.
its trophic level
b.
the humidity and temperature it prefers
c.
its number of chromosomes
d.
when it reproduces

 
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DNA Quiz 2

Name: 

Mendel’s Genetics

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
The law of segregation states that two or more pairs of alleles separate independently of one
another during gamete formation.
2.
Cells that contain a single set of chromosomes are said to be haploid (N).
3.
Crosses involving a study of one gene are called monohybrid crosses.
4.
A dominant allele masks the effect of a recessive allele.
5.
Mendel concluded that the patterns of inheritance are determined entirely by the environment.
6.
A Punnett square represents the phenotype of an organism.
7.
The physical appearance of an individual organism, as determined by the genes it has inherited from its parents, is called its genotype.
8.
Individuals must exhibit a trait in order for it to appear in their offspring.
9.
In codominance, two alleles are expressed at the same time.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
10.
In fruit flies, the gene for long wings, L, is dominant to the gene for short wings, l.  A heterozygous long wing male and a short wing female produce many offspring. The possible genotype(s) among the long-winged offspring is (are)
a.
Ll only
c.
LL and Ll
b.
ll only
d.
Ll and ll.
11.
In drosophila, curled wing is recessive to straight wing. If a homozygous straight-winged fly is mated with a curled-wing fly, how many different phenotypes will be produced?
a.
1
c.
3
b.
2
d.
4
12.
If an organism has two identical alleles for a trait, it is
a.
homozygous.
c.
homozygous dominant.
b.
heterozygous.
d.
heterozygous recessive.
13.
Alleles for the same trait separate during
a.
fertilization.
c.
meiosis I.
b.
mitosis.
d.
meiosis II.
14.
The inheritance of genes that determine one trait (hair color) is not affected by the inheritance of genes that control another trait (tongue rolling).  Which of Mendel’s rules apply to the above statement?
a.
the rule of dominance
c.
the rule of independent assortment
b.
the rule of segregation
15.
In fruit flies, the gene for straight wings, C, is dominant to the gene for curly wings, c. Two flies, when bred, produced 98 straight-winged and 102 curly-winged offspring.  What was the genotype of the curly-winged offspring?
a.
CC
c.
cc
b.
Cc
d.
straight-winged
16.
All homozygous individuals have:
a.
the same genotype
c.
two alleles exactly alike
b.
the same phenotype
d.
a hybrid genotype.
17.
If a family has three daughters, the probability that the next child will be a girl is
a.
1/4.
c.
1/2.
b.
1/3.
d.
3/4.
18.
Mendel explained the reappearance of recessive traits in the F2 generation in his principle of
a.
independent assortment.
c.
dominance.
b.
segregation.
d.
blending inheritance.
19.
If any offspring from a test cross show a recessive phenotype, the parent with the unknown genotype is
a.
heterozygous dominant.
c.
heterozygous recessive.
b.
homozygous dominant.
d.
homozygous recessive.
20.
A homozygous black rabbit is mated with a heterozygous rabbit. If black is dominant over white, they should produce:
a.
all white rabbits
b.
all black rabbits
c.
half black and half white rabbits
d.
one pure dominant and heterozygous individual.
21.
Mendel’s finding that the inheritance of one trait had no effect on the inheritance of another became known as the
a.
law of dominance.
c.
law of segregation.
b.
law of universal inheritance.
d.
law of independent assortment.
22.
The phenotype of an organism
a.
represents its genetic composition.
b.
reflects all the traits that are actually expressed.
c.
occurs only in dominant pure organisms.
d.
cannot be seen.
23.
In humans the ability to taste PTC paper is dominant to non-tasting and hair color shows incomplete dominance (Dark hair x blond hair => brown hair).  A brown haired man who cannot taste PTC paper marries a woman with brown hair and who can taste PTC paper.  Their first child had brown hair and could not taste PTC paper. What are the chances that their next child will be a brown taster?
a.
1/4
c.
1/8
b.
1/2
d.
3/8
24.
Two long-furred cats were mated and produced 25 percent short-furred cats.  The parents were probably:
a.
pure recessive individuals
b.
pure dominant individuals
c.
heterozygous individuals
d.
one pure dominant and heterozygous individual.
25.
When certain types of black roosters are crossed with white hens, speckled chickens result. These chickens, which have a mixture of black and white feathers, show
a.
dominance.
c.
polygenes.
b.
codominance.
d.
recessive
26.
codominance : both traits are displayed::
a.
probability : crosses
c.
homozygous : alleles are same
b.
heterozygous : alleles are the same
d.
Punnett square : chromosomes combine
27.
A Punnett square is used to determine the
a.
probable outcome of a cross.
c.
result of segregation.
b.
actual outcome of a cross.
d.
result of meiosis I.
28.
If a family has four sons, the probability that the next child will be a boy is
a.
1/2.
c.
1/5.
b.
1/4.
d.
4/5.
29.
Suppose that on Mars green creatures are dominant over red creatures and that 3-eyes are recessive to 4-eyes.  Assume that inheritance of traits on Mars occurs the same way as on Earth.  A cross between 2 GgEe Martians would result in what fraction of the offspring being red-3-eyed Martians?
a.
1/16
c.
4/16
b.
2/16
d.
9/16
30.
The fact that a man and woman, both of whom have wavy hair, could have children with curly hair, wavy hair, or straight hair is best explained by the phenomenon called
a.
codominance.
b.
dominance.
c.
incomplete dominance.
d.
None of the above; this would be impossible.
31.
A Punnett square does not show the
a.
genetic makeup of the eggs.
c.
genetic makeup of the sperm.
b.
probable outcome of a cross.
d.
actual outcome of a cross.
32.
The “father” of genetics was
a.
T. A. Knight.
c.
Gregor Mendel.
b.
Dr. Judd.
d.
None of the above
33.
What is the probability that the offspring of a homozygous dominant individual and a  homozygous recessive individual will exhibit the dominant phenotype?
a.
0.25
c.
0.66
b.
0.5
d.
1.0
34.
Which of the following is the designation for Mendel’s original pure strains of plants?
a.
P
c.
F1
b.
P1
d.
F2
35.
F2 : F1 ::
a.
P : F1
c.
F1 : P
b.
F1 : F2
d.
dominant trait : recessive trait
36.
The passing of traits from parents to offspring is called
a.
genetics.
c.
development.
b.
heredity.
d.
maturation.
37.
homozygous : heterozygous ::
a.
heterozygous : Bb
c.
dominant : recessive
b.
probability : predicting chances
d.
homozygous : BB
38.
The phenotype of an organism
a.
represents its genetic composition.
b.
reflects all the traits that are actually expressed.
c.
occurs only in dominant pure organisms.
d.
cannot be seen.
39.
If an individual has two recessive alleles for the same trait, the individual is said to be
a.
homozygous for the trait.
c.
heterozygous for the trait.
b.
haploid for the trait.
d.
mutated.
40.
Tallness (T) is dominant to shortness (t) in pea plants. Which of the following represents a genotype of a pea plant that is heterozygous for tallness?
a.
T
c.
Tt
b.
TT
d.
tt
41.
How many different phenotypes can be produced by a pair of codominant alleles?
a.
1
c.
3
b.
2
d.
4
chp_9_web_tutorial_files/i0440000.jpg
42.
Refer to the illustration above. The genotype represented by the cell labeled “2” is
a.
GgIi.
c.
GI.
b.
GGIi.
d.
Gi.
In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.
      chp_9_web_tutorial_files/i0460000.jpg
43.
Refer to the illustration above. Both of the parents in the cross are
a.
black.
c.
homozygous dominant.
b.
brown.
d.
homozygous recessive.
44.
Refer to the illustration above. The genotypic ratio of the F1 generation would be
a.
1:1.
c.
1:3.
b.
3:1.
d.
1:2:1.
45.
In pea plants, yellow seeds are dominant over green seeds. What would be the expected genotype ratio in a cross between a plant with green seeds and a plant that is heterozygous for seed color?
a.
1:3
c.
4:1
b.
1:2:1
d.
1:1

 
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Chromatography Lab

Chromatography Lab

Problem:  How do you separate the different pigments in a plant?

Materials:

Cone-type (size 4) coffee filter paper (or Whatman #1 chromatography paper)
large glass jars
acetone
distilled water
capillary tubes
fresh spinach
mortar and pestle
clean sand

Introduction:

In this activity you will be experimenting with a technique called chromatography which will allow you to visually demonstrate that the pigment in leaves is a combination of several different colored pigments.

This technique is useful in that it can separate and identify the various components of mixtures, such as those contained in plant pigments. A pigment is a substance that absorbs light at specific wavelengths, chlorophyll is one of these pigments. Its green-yellow in color is due to the absorption of red, orange, blue, and violet wavelengths and the reflection of the green and yellow wavelengths.   This occurs when white light (containing all of the light wavelengths, or the entire spectrum of colors) shines on the leaf surface, all of the wavelengths are absorbed except for the ones you see, which are green-yellow, those are the portions of the spectrum being reflected.

If the conditions are identical, the relative distance moved by a particular compound is the same from one mixture to another. This is why chromatography can be used to identify a compound. The actual identification requires a simple calculation as shown below:

Rf = distance moved by compound from original spot divided by the distance moved by solvent from original spot

It is important to remember that several factors can influence the reliability of the Rf value, these include humidity, temperature, solvent, pigment extract preparation, and the amounts of the material present.  Values are comparable only when the extracts are prepared in the same way and the chromatograms are prepared identically and developed together in the same container.

Acetone is flammable (even the amount found in nail polish remover), keep it away from sparks or open flames. Wear eye protection, especially if using pure acetone.

Procedure

1.   Each lab group (or individual if not working in groups) will need 4 strips of filter paper, approximately 6 inches long and 1 inch wide, 2 chromatography development containers (500 ml beakers or large fruit jars work well), 2 large rubber bands (able to stretch around the vessels from the mouth to the bottom of the vessel), 2 solvents, water and either pure acetone, or nail polish remover.

2.   Do the following with both fresh spinach leaves; tear leaf material and place in a glass container, cover with acetone (this should be done the day before the actual lab activity). An alternative pigment extraction technique is to use a
mortar and pestle. Place plant material the vessel, add a little clean sand, some acetone and then grind until a dark green liquid appears.    Both techniques yield very dark pigments with which to work. Be certain to keep the pigments apart throughout the entire activity.

3.   Place one of each solvents (water and acetone, or nail polish remover) in the chromatography vessels and stretch a rubber band length-wise around each vessel. The rubber band will be the mechanism for hanging the chromatography strips.

4.   Make a pencil mark on each of the 2 chromatography strips, in the center, directly above the point of the strip, about 1 inch from the tip of the paper. Using a capillary tube, or tooth pick, apply the plant pigment to each filter paper strip. This is done by touching the tooth pick or capillary tube which has been dipped in the pigment, to the pencil mark. Make an application, then wave the paper gently to dry it a little before the next application. Be patient, you will need 12 to 15 applications.

5.   By now you should have 2 strips with spinach pigment.  Suspend one of each in each of the chromatography development vessels. You can attach them with paper clips, or simply fold over a portion of the end and it should hang in place. The tip of each strip should just touch the solvent.

6.   Wait 20 to 30 minutes for the chromatograms to develop. Remove the chromatograms. Mark with a pencil (NOT a pen) where the solvent stopped as it moved up the chromatogram. This is called the solvent front. Mark also where each pigment stopped moving up the chromatogram. Using the equation below, determine a reference number for each pigment on the chromatograms. Depending on which chromatogram you are viewing, you should see greens, yellow/yellow orange, and red. All measurements should be in mm. (Any material which did not move from the
pencil dot is insoluble).

Rf = distance moved by compound from original spot divided by the
distance moved by solvent from original spot

Note: each pigment has a special name,
green = chlorophyll a or b
yellow/yellow orange = carotene
red = anthocyanin
brown = xanthophyll

The reference numbers for the chlorophylls in this activity are:
0.28 = chlorophyll a, 0.18 = chlorophyll b (spinach). You need these
numbers so that you can determine one chlorophyll from the other.
Calculate reference fronts for all of your pigments.

See if your calculations come close to those above for chlorophyll a and b.

Note:  You can use different solvents such as mixtures involving petroleum ether
to do this sort of paper chromatography.

To view notes and a graphic showing a separation of plant pigments involving
paper chromatography, click here.  Can you calculate the Rf values for the
pigments separated in this graphic?

Conclusion Questions

1.  What reference numbers (Rf) did you calculate for chlorophyll a and chlorophyll b?
2.  With what you have discovered about pigments, what conclusions can you
make regarding the changing color of leaves in autumn?
3.  What adaptive purpose do different colored pigments serve for a plant?
4.  Why do some pigments move farther up the chromatogram than others?
5.  What are some possible sources of error in this lab?

Paper chromatography is a technique used to separate a mixture into its component molecules. The molecules migrate, or move up the paper, at different rates because of differences in solubility, molecular mass, and hydrogen bonding with the paper.

For a simple, beautiful example of this technique, draw a large circle in the center of a piece of filter paper with a black water-soluble, felt-tip pen. Fold the paper into a cone and place the tip in a container of water. In just a few minutes you will have tie-dyed filter paper!

Separation of black ink pigments

The green, blue, red, and lavender colors that came from the black ink should help you to understand that what appears to be a single color may in fact be a material composed of many different pigments —and such is the case with chloroplasts.

chromatography setup

 

In paper chromatography the pigments are dissolved in a solvent that carries them up the paper. In the ink example, the solvent is water. To separate the pigments of the chloroplasts, you must use an organic solvent

 

 

pigment separation

 

pigment separation

 

Analysis of Results I

If you did a number of chromatographic separations, each for a different length of time, the pigments would migrate a different distance on each run. However, the migration of each pigment relative to the migration of the solvent would not change. This migration of pigment relative to migration of solvent is expressed as a constant, Rf (Reference front). It can be calculated by using the formula: