Heredity and Adaptation Teaching Slides, 2.1 Part 3 If you are using the PowerPoint slides, log in to your FOSSweb account on your internet browser. Then, cut and paste these links into your browser. Resources by Investigation provides access to all notebook masters, teacher masters, online activities, and video content: http://www.fossweb.com/resources-by-investigation?folioID=G4302820&parentID=G4302819 The eBook provides access to all FOSS Science Resources articles: http://www.fossweb.com/delegate/ssi-wdf-ucm-webContent/Contribution%20Folders/FOSS/ebooks/NG_Heredity_and_Adaptation_FB_SRB/index.html If you are using the PDF versions of the slides, simply log in to your FOSSweb account before starting; the embedded links will take you directly to the Resources by Investigation and the eBook. If you plan to use these slides offline, be sure to plan ahead and download the necessary duplication masters from the Resources by Investigation section of FOSSweb.

Science Log Q3 Week 9: Wednesday 3/8: What is the function of the digestive system of animals such as Pacific treefrogs? Heredity and Adaptation Course, 2.1: Lines of Descent

Reading Read “Tree Thinking” in FOSS Science Resources on page 17-21. As you encounter new information, example, or diagrams about these and other concepts discussed in the article, put on page 71. Heredity and Adaptation Course, 2.1: Lines of Descent Step 15

Discuss time How is time represented on the cladogram? There is an arrow labeled time on the left side of the cladogram. Older things on the bottom and newer on the top, as shown by the arrow on the left. Can you tell how much time has passed? No, only relative time. That is a limitation of this model. Follow the questions and discussion in steps 16-18 in the FOSS Investigations Guide. Heredity and Adaptation Course, 2.1: Lines of Descent Steps 16-18

17. Find the common ancestor Determine how common ancestors are represented on your cladogram. Where do mammals branch off from the other organisms? This point represents an ancestor of mammals. That means that from this common ancestor, mammals branched off. Every intersection on the cladogram represents a common ancestor of some sort. Circle the intersection on your cladogram where mammals branch off from the other animals. This point is a common ancestor of all mammals Heredity and Adaptation Course, 2.1: Lines of Descent

17. Common ancestors Return to your model analysis chart. Add arrows and intersections to the left column, then work in your group to fill in what those parts represent. Add limitations of time that you just discussed. Heredity and Adaptation Course, 2.1: Lines of Descent

17 common ancestor What other animals on the cladogram have this same ancestor? The bird and the alligator. What point represents the most recent common ancestor of birds and alligators? The point where birds and alligators branch off. How do you know? There is no other branching between them. Is the frog an ancestor of humans? Explain. No, but frog and humans share a common ancestor. Where would you place a circle to represent an ancestor to all the following animals: frog, human, rabbit, bird, alligator? Where the frog branches. There is no direct ancestor/descendant relationship between frogs and humans. Heredity and Adaptation Course, 2.1: Lines of Descent

18. Discuss Fossils How might we know what the common ancestor of frogs and humans may have been? Where could we look for information? The fossil record What characteristics would the common ancestor of frogs and humans exhibit? Four limbs, bony skeleton, vertebrae. Heredity and Adaptation Course, 2.1: Lines of Descent

18. Discuss Fossils Sometimes there are no fossils that demonstrate the relationship between ancient and current organisms. Cladograms are considered to be hypotheses based on shared characteristics of current organisms and known extinct organisms. Each group of cladogram shares specific common characteristics, and each group contains descendants of a common ancestor. As more information is discovered, it sometimes turns out that organisms are not as closely related as was thought. Heredity and Adaptation Course, 2.1: Lines of Descent

18. Discuss Fossils The organisms that share a more recent common ancestor are more closely related, just as a child is more closely related to its parents than it is to its great-grandparents. Heredity and Adaptation Course, 2.1: Lines of Descent

Focus on time Refer to the time arrow Can you tell how much time may have passed between each bar and tip? No. The lines show only the sequence of changes. For instance, the shark branched off before the tuna. Does the cladogram give us information about how much time has passed from the first bar to the present? No, Depending upon the cladogram, thousands or millions of years may be represented. Heredity and Adaptation Course, 2.1: Lines of Descent Step 11

Add information to the picture How do ancestors, including parents, pass on their characteristics to their offspring? Genetic material, DNA, genes Heredity and Adaptation Course, 2.1: Lines of Descent Step 20

Add information to the picture Until the 1950’s, scientists were not able to use genetic information to determine relationships. In the 1950’s, the structure of DNA was pieced together by James Watson (1928-), Francis H. Crick (1916-2004), and Maurice Wilkins (1916-2004). Now, relationships between groups of living organisms can be determined by how similar their DNA is. DNA similarities van be used as a vertebrae, amniotic eggs, and hair are used. Technology???? Heredity and Adaptation Course, 2.1: Lines of Descent

21. Examine One aspect of a well-developed model is that it helps you incorporate new data and make predictions about new situations. Sometimes scientists need to revise their model when they get more data. In this case, we will consider a different species, the dolphin. Heredity and Adaptation Course, 2.1: Lines of Descent

Examine the dolphin Place the dolphin on the cladogram where you think it belongs. Support your decision with evidence and reasoning. Heredity and Adaptation Course, 2.1: Lines of Descent Step 21

Review embryo development Where should we place the dolphin on the cladogram? Dolphins have amniotic egg and hair. Is it a tetrapod? Heredity and Adaptation Course, 2.1: Lines of Descent Step 22

Review embryo development Teacher master T, Dolphin Embryo Development It van be helpful to look at an organism in various life stages, not just when it is an adult. The photographs represent the development of a dolphin embryo before it is born. What do you observe and what inferences can you make? Explain how this image provides evidence that a dolphin is a tetrapod. Where should we place the dolphin on the cladogram? With the mammals. Heredity and Adaptation Course, 2.1: Lines of Descent Step 22

Discuss the reading Open your notes on “Tree Thinking.” In your group, share one thing you learned from the article. Heredity and Adaptation Course, 2.1: Lines of Descent Step 23

Review vocabulary Spend a few minutes reviewing the vocabulary for this part. Update the vocabulary index and table of contents in your notebook. Heredity and Adaptation Course, 2.1: Lines of Descent Step 24

Review vocabulary characteristic a trait that helps identify an organism cladogram an evolutionary tree diagram based on shared characteristics common ancestor an organism from the past that is related to all the organisms in the group descendant an organism related to an organism that lived earlier limitation the quality of being restricted, such as what information is being shown in a model most recent common ancestor the first organism from the past that is related to all the organisms in the group related belonging to the same group or family; connected by common ancestry species a group of organisms that can interbreed or pass on its genes to following generations Heredity and Adaptation Course, 2.1: Lines of Descent

25. Summarize All life is related. We can use diagrams called cladograms to map which characteristics organisms share and determine which species share common ancestors. Now there are sophisticated tools we can use to examine genetic material (DNA) to collect data and develop cladograms to model how closely organisms are related. Heredity and Adaptation Course, 2.1: Lines of Descent

Answer the focus question page 68 How can a model help us understand the relationships among organisms? At first I thought ____. Now I think ____ because ____ . Heredity and Adaptation Course, 2.1: Lines of Descent Step 26

Homework Teacher master U, Green-Plant Cladogram Notebook sheet 7, Green-Plant Cladogram Questions Answer the questions on the notebook sheet. Heredity and Adaptation Course, 2.1: Lines of Descent Step 27

Wrap-Up/Warm-Up “Noticing patterns is often a first step to organizing and asking scientific questions about why and how the pattern occurs.” Brainstorm other examples of patterns in nature. How do those patterns help you better understand and appreciate the world around you? Quote is from A Framework for K-12 Science Education. Heredity and Adaptation Course, 2.1: Lines of Descent Step 24

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