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Introduction

Botana curus is a valuable plant because it produces Curol, a compound used for treating certain kinds of cancer. Curol cannot be produced in the laboratory. Botana curus grows very slowly and is on the endangered species list, so its ability to provide Curol in large quantities is limited.
Species that are more closely related to Botana curus are more likely to produce the important substance Curol. Three similar plant species that are plentiful (X, Y. and Z) may be related to Botana curus. You will work as a researcher to:
• gather structural and molecular evidence to determine which plant species is most closely related to the hypothetical species, Botana curus
• use this evidence to decide which plant species is most likely to serve as a source of the important substance Curol

Safety
• You will need to wear goggles while conducting Tests 4 and 5.
• Do not eat or drink anything in the laboratory while doing this laboratory activity.
Important Note: Record all of your data and answers on these laboratoty sheets. You will need to keep them for review before the Regents Examination. Later, you will need to transfer your answers to a separate Student Answer Packet. Your teacher will use the packet in grading your work, and the school will retain it as evidence of your completion of the laboratoiy requirement for the Living Environment Regents Examination.

Structural Evidence for Relationships
Perform the following tests and record your observations in Table 1. Use a hand lens or microscope as needed.

Test 1—Structural Characteristics of Plants
a. Do not remove the plant samples from the plastic bags/cards.
b. Compare the structural characteristics of the plant samples. Record your observations in Table 1.

Test 2—Structural Characteristics of Seeds
a. Do not remove the seed samples from the plastic bags/cards.
b. Compare the structural characteristics of the seed samples. Record your observations in Table 1.

Test 3—Microscopic Internal Structure of Stems
a. Use the lowest magnification on your microscope to examine the slides that show cross sections through stems of Botana curus and Species X. Y, and Z. Compare the arrangement (circular or scattered) of the bundles of conducting tissue in the specimens. Refer to Figure 1.

b. Record your observations (using words and/or diagrams) of the conducting tissue arrangement in Table 1.

Hypothesize: Tests 1-3
a. Based on your data for structural relationships, which species (X, Y, or Z) would you hypothesize is most likely to produce Curol?
b. Explain, how the evidence from your data table supports your hypothesis. You will test your hypothesis by completing additional tests in the second part of this laboratory activity.

Molecular Evidence for Relationships
Test 4 - Paper Chromatography to Separate Plant Pigments
a. You must wear safety goggles when performing this part of the activity.
b. Draw a pencil line 2 cm from the bottom of the chromatography paper. Use a pencil to label the top edge of the chromatography paper Bc (Botana curus), X. Y, and Z as shown in Figure 2.
c. Use a clean microtip dropper to transfer two drops of the plant extract from Botana curus just above the pencil line as shown in Figure 2.

d. Using a clean dropper each time, repeat the procedure to place drops of the other plant extracts in the appropriate locations on the paper.
e. Add just enough water to cover the bottom of the cup approximately 1cm deep. The water should NOT be high enough to touch the spots of plant extract on the chromatography paper when the paper is placed in the cup.
f. Fold the chromatography paper and stand it in the cup as shown in Figure 2.
g. The chromatography paper must be removed from the cup before the water line reaches the pencil labels at the top of the chromatography paper While the plant extracts are moving in the chromatography paper, go on to Test 5, but keep checking on the progress of the water moving up the paper so that you can remove it at the proper time.
h. Once the chromatography is done, record your observations of the colors and relative amounts of pigments in Table 1
i. Clean the microtip droppers thoroughly by rinsing them with water. Carefully pour solutions from the chromatography cup into the waste container. Discard the used chromatography paper.

Test 5—Indicator Tests for Enzyme M
a. You must wear safety goggles when performing this part of the activity.
b. It is not practical to test a plant directly for Curol. However, if enzyme M is present, a plant may produce Curol.
c. Test the plant extract from Botana curus for the presence of enzyme M. Put one small scoop of indicator powder into one depression of the well tray. Use a clean microtip dropper to add 5 drops of Botana curus extract to the indicator powder. A fizzing reaction indicates that enzyme M is present.
d. Repeat the test for enzyme M using the other plant extracts.
e. Record the results of your tests for enzyme M in Table 1.
f. Clean the microtip droppers thoroughly by rinsing them with water. Rinse the well tray and blot it dry using a paper towel.
Reminder: Complete the chromatography tests and observations before going on.

Test 6—Using Simulated Gel Electrophoresis To Compare DNA
a. For this test, you will use the plastic bags containing colored paper strips representing portions of DNA molecules. The letters on these strips represent the sequence of bases in DNA molecules isolated from Botana curus and Species X. Y, and Z.
b. To compare DNA molecules, scientists use enzymes that bind to and cut specific base sequences within the DNA. Imagine that you are using an enzyme that binds to the base sequence CCGG and cuts between the C and G. Simulate this cutting process as follows:

c. Scientists use gel electrophoresis to separate the DNA fragments resulting from this binding and cutting process. In an electrical field, the negatively charged DNA molecules migrate through a gel-like material toward the positively charged pole. The smaller molecules migrate more rapidly through the gel than the larger ones do.
d. Simulate the electrophoresis process by placing the DNA fragments from Botana curus appropriate well on the Simulated Electrophoresis Gel (Table 2). Simulate the effect of electrical current on the DNA fragments by counting the number of letters (bases) in each of the fragments and moving them to the appropnate location on the electrophoresis geL Refer to the number of DNA letters indicated along the left side of the gel to determine the final position for each fragment.
e. Call your teacher over to check your work for Botana curus before you continue with the DNA from the other species.
f. Mark a horizontal line to indicate the final position of each fragment of Botana curus DNA on the simulated electrophoresis gel (Table 2), then record the size on the fragments (number of bases in each) in Table 1.
g. Repeat this process for each of the other species (X, Y, and Z): lightly shade the CCGG sequences, cut the DNA, and separate the resulting fragments.
h. Mark the final position of the DNA bands for each species on the gel (Table 2), then record the size of the fragments (number of bases in each) in Table 1.
i. Discard the used paper DNA fragments and return all other materials to their original location.

Test 7—Translating the DNA Code To Make a Protein
a. The sequences of DNA bases below represent parts of the genes responsible for the production of one type of protein, an enzyme, produced by Botana curus and Species X, Y, and Z.
b. Under each DNA sequence, write the complementary messenger RNA base sequences that each of these gene fragments would produce. Note: Unlike during DNA replication of messenger RNA, the DNA base “A” specifies the RNA base “U.”
c. Use the universal genetic code table that your teacher provides to translate the messenger RNA base sequences into sequences of amino acids in the protein produced by each species. Write the sequences of amino acids under the messenger RNA sequences.

• State how the amino acid sequence you obtained from the gene fragment for Botana curus compares with the sequences for the other three species.
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•Summarize your observations of the number of differences in Table 1.

Analysis of Results
1. Using the information in Table 1, identify which plant is most closely related to Botana curus and therefore most likely to produce Curol. _____________________ Explain your choice by citing specific evidence from your research.
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2. Did the addition of molecular evidence support or refute the hypothesis that you made earlier based
on structural evidence only? Explain why or why not.
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3. Which kind of evidence—structural or molecular—is most helpful in making decisions about
relationships between species? — Explain why.
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4. Based on your observations, list three characteristics (structural or molecular) that all four species have in common.
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5. Provide a biological explanation for the common characteristics that these species share.
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6. Scientists frequently use branching tree diagrams to represent graphically the relationships between species. Which branching tree, shown below, best represents the relationships among the four species?__________________

Explain how you used the information on the data table to select this tree.
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7. State two additional kinds of evidence you might use to further support your hypothesis about the relationship between Botana curus and species X. Y, and Z.
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Base your answers to quesuons 8 through l0 on the reading passage below and on your understanding of biology.

Assume that the plant you identified as being closely related to Botana curus grows rapidly, survives in many environments, and produces Curol. News reports indicate that Botana curus plants may become extinct unless expensive efforts are made to preserve the species. Members of your research team disagree as to whether or not Botana curus should be saved.

8. State three examples of human activities that could endanger Botana curus.
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9. State three reasons why it might be important to preserve Botana curus.
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10. State two arguments people might make for NOT preserving Botana curus.

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