BIOL MISC Student Exploration: Cladograms Gizmos with all the correct answers

Name: ALAQ HAMEED Date: BIOL MISC Student Exploration: Cladograms Gizmos with all the correct answers Student Exploration: Cladograms Vocabulary: adaptation, amino acid, amnion, artiodactyls, bipedal, clade, cladistics, cladogram, convergent evolution, evolution, flower, mammary glands, molecular, morphological, multicellular, parsimony, sagittal crest, phloem, selenodont teeth, SNP, xylem Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. Look at the images below. Which two organisms do you think are most closely related? Turtle and Deer Worm Deer Turtle 2. Why do you think so? Because they both are vertebrates (have a backbone) but the worm doesn’t. Gizmo Warm-up Cladistics is a method of hypothesizing the evolutionary relationships between species. A cladogram is a branching diagram that illustrates these relationships. For example, the cladogram on the right shows that deer are more closely related to turtles than to worms. In the Cladograms Gizmo, you will use morphological (physical characteristics) and molecular data to create cladograms. To begin, make sure Plants is selected for the Organism group and Morphological is selected for the Data type. Click on one of the characteristics to the left of the table on the TABLE tab. Information about the characteristic will be shown on the ORGANISM tab. Using the information on the ORGANISM tab, describe each of the characteristics below. • Xylem and phloem: Xylem and Phloem are tissues in plants that transport water and solutes up the plant (phloem) and food down the plant (xylem). • Flowers: A flower is a part of a plant containing reproductive organs (stamen and carpel) surrounded by brightly colored petals. • Multicellularity: A multicellular organism is composed of more than one cell. Question: How do you build a simple cladogram based on physical characteristics? By shared derived characterstics. 1. Fill in: Using what you learned in the warm-up, fill in the table. Clicking one of the boxes of the table will add a check mark to indicate the presence of a characteristic. Then, select Check table and adjust any of the boxes you may have filled in incorrectly. Which organism has the fewest shared characteristics? Flowers 2. Organize: Now you are ready to organize the table. A. How many characteristics (check marks) does each organism have? Algae: 0 Arabidopsis: 3 Cycad: 2 Moss: 1 Drag the arrows ( ) below the table to order the organism columns from fewest characteristics on the left to most on the right. B. How many organisms have each characteristic? Multicellularity: 3 Xylem and phloem: 2 Flowers: 1 Drag the arrows to the right of the table to order the characteristics from fewest organisms on the top to most on the bottom. 3. Build: Select the CLADOGRAM tab at the top left. The goal of a cladogram is to show the relationships among a group of organisms. Organisms that are most closely related should share the most recent common ancestor (highest branch on the tree). Organisms that are most distantly related should share the oldest common ancestor (lowest branch on the tree). Click the segments on the cladogram template to build your own cladogram that shows how you think the different plants are related. Sketch you cladogram in the space to the right. Answer the following questions based on your cladogram. A. Which two organisms are most closely related? Algae and Arabidopsis B. Which organisms are most distantly related? Arabidopsis, Moss, and Cycad (Activity A continued on next page) Activity A (continued from previous page) 4. Analyze: On a completed cladogram, the orange dot that connects two branches represents a common ancestor. In the cladogram to the right, organisms B and C descended from a common ancestor (D) that was more recent than the common ancestor (E) of organisms A, B, and C. Describe how the organisms in your cladogram are related through common ancestors. 90 The Algae and Moss are common ancestors. The Algae and the cycad are also common ancestors. And lastly the Arabidopsis and the Algae are common ancestors. 5. Label: The purple lines represent a characteristic change, or adaptation. On the cladogram above, organisms B and C share characteristic 3. Organism B either gained or lost characteristic 1 after diverging from organism C. In the Gizmo, select a purple line to open a text box and fill in the characteristics. Based on your cladogram, from oldest to newest, in what order did the three characteristics (flowers, multicellularity, and xylem/ phloem) evolve? Newer to older: Flowers, Xylem and phloem and multicellularity. 6. Score: The parsimony principle states that the most likely solution is usually the simplest. In general, biologists try to create cladograms that require the fewest evolutionary changes. For example, it is more likely that xylem and phloem evolved once rather than multiple times. The “parsimony score” calculates how many changes occur in a given cladogram. A. How many changes (purple lines) occurred in your cladogram? 3 B. Select Show parsimony score. What is the score of your cladogram? 3 C. Select Show best possible parsimony score. Have you created a cladogram with the least number of possible characteristic changes? yes 7. Revise: If you have not created a cladogram with the lowest possible parsimony score, adjust the cladogram until you do. Make sure that the organisms are ordered from fewest shared characteristics on the left to most shared characteristics on the right.