Leaf Collection Instructions

Arkansas is essentially a forest state because more than half of the state is covered with trees.  The climate and soils of Arkansas also support a great variety of trees, both conifers and deciduous.  Trees are one of Arkansas’ most important crops.  Forests are also valuable in preventing erosion, in offering parks and recreational areas, and in providing homes for wildlife.  In addition, many trees have been introduced into the state as ornamentals.

Leaf collecting is a good way to learn the trees native to your area.  Collecting leaves will also help you to learn leaf margins, shapes, and  venations and how to use different taxonomic keys to identify trees.

Materials needed:

  • leaf press
  • black ink pen
  • pencil
  • small notebook
  • scissors
  • Elmer’s glue
  • art paper, poster board, etc. for mounting
  • labels
  • taxonomic keys (Trees of Arkansas published by the Arkansas Forestry Commission)

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Directions for making a leaf press:
1.   Cut 15 – 20 pieces of corrugated cardboard 30 cm by 50 cm in size.
2. Cut several sheets of newspaper the same size as the cardboard.
3. Lay 10 or 12 sheets of newspaper between each cardboard layer sandwich style.  These sheets will need to be changed every couple of days as they absorb moisture from your leaves; therefore, cut extra sheets.
4. Use one, preferably two, stretch belts to bind the press together.
5. Leave the press in an area so that air can circulate &  more quickly dry the leaves.

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Getting started with your collection:
1. Study the shapes, margins, venations, tips, bases, etc. in your Trees of Arkansas book.

Click here to view reference page

2. Learn to distinguish simple leaves from compound leaves and conifers from deciduous trees.
3. Learn to distinguish a tree from a shrub.
4. Gather your collecting materials together – press, pencil, scissors, & small notebook.
6. Always get permission before collecting leaves on someone else’s property.
7. Be sure to collect at least
two of each type of leaf so both the bottom & top side of the leaf can be shown in your collection.
8. Place leaves in your press immediately after collecting them so they do not start to dry out and wrinkle.
9. Record the name of each leaf, date collected, and place collected in your notebook as you collect.  Also record tree characteristics such as shape of the crown, color and type of bark, etc.

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Collecting:
1. Remember to collect two of every type of leaf!
2. Carefully remove an entire leaf, not a leaflet, from the tree, and place this in your press between newspaper layers.
3. If leaves are damaged or torn, don’t use them because you will not receive credit.
4. Make sure that none of the leaf parts extend beyond the edge of the press.
5. You may also collect &press seeds and/or fruits from some trees if they fit in your press.
6. Leave the leaf in the press for 3 – 5 days depending on its thickness and moisture content.  Remember to change the newspaper when needed.
7. Keep the press in an area where air is circulating (in front of a fan).

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Labeling and identifying:
1. Obtain printed labels from your teacher.
2. Use only black ink to write labels, & do not mark out or white out mistakes on the labels; rewrite them.
3. Use taxonomic keys to identify each leaf, and include both the scientific & common name of the tree on the label.
4. Determine the shape, margin, tip, base, and venation of your leaf and whether it is a simple or compound leaf; record this on your label.
5. Use you key to give a description of the tree, not the leaf.
6. Research uses for the tree, its fruit, etc. and record on your label.
7. Tell if the leaf is deciduous or coniferous.

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Mounting leaves:
1. Use pieces of cut poster board or art paper to mount your leaves.  Make sure all sheets are uniform in size! (The size of your sheets will be determined by your largest leaf.)
2. Use Elmer’s glue to adhere two leaves to each page — one showing the upper surface of the leaf and the other showing the underside of the leaf.
3. Each page should have only one type of leaf on it.
4. Arrange the leaves so they do not overlap each other and so there is room to glue the label in the lower right hand corner.  The leaves should look nice on the page.
5. On compound leaves, mount the topside of the complete leaf and then mount the underside of a single leaflet. Make sure the leaflet comes from another leaf to receive credit!
6. Use a small amount of Elmer’s glue to adhere the completed label in the lower right hand corner of the page.
7. LET THE PAGES DRY COMPLETELY BEFORE ASSEMBLING THEM TOGETHER IN YOUR COLLECTION OR THE PAGES WILL STICK TOGETHER!!!!!
8. Once the pages are dry, lay them in the correct order (see your list of required leaves), and then number the pages in the lower right corner with black ink.
9. Make a stiff front and back cover for your collection from poster board, cardboard, wood, etc.  Include the following items on your cover:

  • title (Tree Identification Through Leaves)
  • your complete name
  • date collection turned into teacher
  • class period
  • subject
  • teacher’s name

10. Use ribbon, string, etc. to bind the pages together or assemble the collection in a scrapbook.  DO NOT COVER THE LEAVES WITH PLASTIC!!!

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Required leaves:
1. Only native, Arkansas trees may be used.  Refer to your Trees of Arkansas book.
2. Leaves must be in perfect condition without damage or tears.
3. No more then 4 oaks are allowed in the collection.
4. No fruit trees such as apple, pear, orange, peach, etc. are allowed.
5. Place the following leaves in your collection first and in this order:

  • sweet gum
  • American sycamore
  • pine (any type)
  • flowering dogwood
  • redbud
  • ash (any type)
  • persimmon
  • Eastern red cedar
  • red or silver maple
  • hickory (any type)
  • pecan
  • pin oak
  • willow oak
  • water oak
  • elm (any type)

6. The remaining leaves that you include must be trees native to Arkansas!

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*Pre AP Biology is required to collect 30 leaves including the 15 required.

 *Biology I is required to collect 20 leaves including the 15 required.

   Pre AP      Biology I

Introduction to Plants PPT Questions

Introduction to Plants
ppt Questions

Early Ancestors

1. The first habitat for plants on earth was _____________.

2. Which algal group is most related to early land plants?

3. What is this group of algae called?

4. List 5 similarities between algae and terrestrial plants.

     a.

     b.

     c.

     d.

     e.

5. List 5 helpful adaptations aquatic plants have by being surrounded by water.

     a.

     b.

     c.

     d.

     e.

6.Complete the following table explaining how terrestrial plants solved the move onto land.

 

Plant Adaptations to land
Problems: Solutions:
Need Minerals
Gravity
Increase in Height to get Light
Adaptations for drier environment
Reproduction

 

How Are Plants All Alike

7. All plants are ____________________.

8. Plants can make their own food by a process called ____________________.

9. Since plants make their own food they are called _________________.

10. Plants contain what type of chlorophyll?

11. Where is chlorophyll found in plants?

12. What surrounds the outside of all plant cells and what is it composed of?

13. How do plants store their reserve food?

14. The life cycle of plants is known as __________________ of _________________.

15. The dominant stage of the plant is the diploid (2n) ________________ stage.

16. The eggs and sperm are produced during the haploid (1n) ________________ stage.

17. The gametophyte stage produces a multicellular plant ______________ that is protected inside an ____________ ___________.

18. The sporophyte stage produces _____________ by _____________.

19. Haploid spores undergo ______________ to produce the _______________ stage.

20. The gametophyte stage makes _____________ called the _________ and ___________.

21. Label the diagram of alternation of generation. Include the sporophyte and gametophyte generations, the chromosome number (2n or 1n), and where mitosis and meiosis occur.

Plant Divisions

22. Plants are divided into __________ groups based on the presence or absence of an ___________ _____________ ___________ for carrying water and dissolved _____________.

23. What is the transport system for water and minerals called?

24. ______________ plants lack vascular tissue and are called _______________.

25. In what type of environment must nonvascular plants live?

26. Give an example of a bryophyte.

27. Nonvascular plants can’t grow as tall as vascular plants. Explain why.

 

28. The cells of nonvascular plants must be in _________ contact with water because water moves by _______________ from cell to cell.

29. How does the sperm get to the egg in nonvascular plants?

30. Name 3 divisions of nonvascular plants and give and organism found in each division.

     a.

     b.

     c.

31.Vascular plants are also called _______________.

32. What are the 2 subdivisions of vascular plants?

     

33. Name 4 divisions of seedless vascular plants and give an example of a plant in each group.

     a.

     b.

     c.

     d.

34. Name the 2 groups of seed-bearing vascular plants.

 

35. Gymnosperms have ____________ seeds found inside cones.

36. Angiosperms have ___________ to attract ____________ so seeds can be produced.

37. Name the division known as conifers and tell several plants in this group/

 

38. Name 2 other divisions of gymnosperms and tell a plant in each group.

     a.

     b.

39. Name the oldest living plant.

40. Name the tallest living plant.

41. What group are these 2 plants in?

42. Angiosperms are called ____________ plants.

43. How are seeds formed in angiosperms?

 

44. Where is the ovary found?

45. Name the male and female parts of a flower.

46. How are fruits formed?

47. Angiosperms are the division ______________.

48. What are the 2 subgroups of Anthophyta.

49. Describe the characteristics of monocots.

 

50. Describe the characteristics of dicots.

 

 

 

 

Chromatography of Plant Pigments Sample 2 PreAP

 

Chromatography of Plant  Pigments

 

Introduction

Chromatography is a way of separating a mixture using differences in the abilities of the components to move through a material. All chromatography involves two phases – a stationary phase and a mobile phase. The movement of the mobile phase through the stationary phase allows separation to take place. Because the components of a mixture move at different rates, they eventually separate.

Paper chromatography is a common way to separate various components of a mixture. The components of the mixture separate because different substances are selectively absorbed by paper due to differences in polarity. A solution can be separated by allowing it to flow along a stationary substance. Water or some other solvent is used as the mobile phase. The solvent moves upward along the paper because of capillary action. As it reaches the spot, the mixture dissolves in the solvent. For instance, the pigments in an ink solution can be separated by passing the ink through a piece of paper. The pigments respond differently to the paper. The differences in the migration rates result in differences in the distances the separated components travel, some pigments are held back while other moves ahead. Eventually, a pattern of colors results that shows the separated pigments.

Hypothesis

Paper can be used to separate mixed chemicals.

Materials

The materials used for this lab are paper, pencil, scissors, eraser, filter paper, test tube, cork, paper clip, metric ruler, black felt-tip pen, and a calculator.

Methods

The first step to this experiment was to bend a paper clip so that it is straight with a hook at one end. Push the straight end of the paper clip into the bottom of a cork stopper. Next, hang a thin strip of filter paper on the hooked end of the paper clip. Insert the paper strip into the test tube so it does not touch the sides, but almost the bottom of the test tube. Next, remove the paper strip from the test tube and draw a solid 5 mm wide band about 25 mm from the bottom of the paper, using a black felt tip pen. Use a pencil to draw a line across the top of the paper strip 10 cm from the top.

Pour about 2 mL of water into the test tube with the bottom of the paper in the water and the black band above the water. Observe what happens as the liquid travels up the paper. Record the changes you see. When the solvent has reached the pencil line, remove the paper from the test tube. Let the paper dry on the desk. With a metric ruler, measure the distances form the starting point to the top edge of each color. Record the data in a data table. Calculate a ration for each color by dividing the distance the color traveled by the distance the solvent traveled.

Results

The results of the experiment are shown in a chart and a graph.

Distance color traveled and Rf value.

 

Color of ink (list in order Distance traveled by each color (mm) Distance solvent traveled (mm) Ration traveled =
Distance color moved /Distance water moved
Yellow 50 120 5/12
Orange 85 120 17/24
Pink 100 120 5/6
Red 105 120 7/8
Blue 115 120 23/24
Violet 120 120 1

 

Questions

1. How many colors separated from the black ink? Six colors separated from the black ink: yellow, orange, pink, red, blue, violet.

2. What served as the solvent for the ink? Water served as the solvent because it is the universal solvent.

3. As the solvent travel up the paper, what color appeared first? Orange appeared first as the solvent traveled up the paper.

4. List the colors in order from top to bottom that separated from the black ink? The colors that separated from top to bottom: violet, blue, red, pink, orange, and yellow.

5. In millimeters, how far did the solvent travel. The solvent traveled 120mm.

6. From your results, what can you conclude is true about black ink. That black ink is a combination of several colors and that can be separated by water.

7. Why did the inks separate? The ink separated because each pigment has its own characteristics and molecular structure.

8. Why did some inks move a greater distance? Different pigments were absorbed at different rates.

Error analysis

There could be an error by the way the ink was distributed on the paper or by the amount of water put in the test tube.

Conclusion

The hypothesis was correct. This experiment showed the way black ink could be separated. Black ink is made from a various colors— yellow, orange, pink, red, blue, and violet. The colors separate because of the differences in their molecular characteristics, their solubility in water and their rate of absorption by the paper.

BACK

 

Chlorophyll Fluorescence

 

Chlorophyll Fluorescence

INTRODUCTION

When a pigment absorbs light, electrons of certain atoms in the pigment molecules are boosted to a higher energy level. The energy of an absorbed photon is converted to the potential energy of the electron that has been raised to an excited state. In most pigments, the excited electron drops back to its ground-state, or normal orbit, and releases the excess energy as heat. Some pigments, including chlorophyll, emit light as well as heat after absorbing photons.
In the chloroplast, these excited electrons jump from the chlorophyll molecule to a protein molecule in the thylakoid membrane, and are replaced by electrons from the splitting of water. The energy thus transferred, is used in carbohydrate production.
This release of light is called fluorescence. Chlorophyll will fluoresce in the red part of the spectrum, and also give off heat. In this lab, you will observe this fluorescence by separating the chlorophyll from the thylakoid membrane.

MATERIALS

 

Spinach leaves Flashlight or small lab light
Mortar and pestle Test tube
Acetone Filter paper
25-mL graduated cylinder Funnel
Ring stand or funnel rack Safety goggles

PROCEDURE

1. Grind the spinach leaves using a mortar and pestle.

2. Add acetone to the ground leaves, using enough acetone and spinach leaves to get between 10 and 15 mL of extract.

3. Set up your filtering apparatus, and using proper filtering technique, filter the extract to a test tube. NOTE: Use a small amount of acetone to wet the filter paper, to hold it into place, instead of water.

4. Shine a flashlight, or other similar light source, through the test tube and extract.

5. Observe the fluorescence of the chlorophyll at a 90 degree angle to the flashlight.

 

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: