Evidence for Evolution Question and Answer Key

Evidence for Evolution How are DNA and comparative anatomy used to show relatedness? Why? “You look just like your mother!” “He has his father’s eyes.” These comments that refer to the similarities between parents and their children are heard often in conversation. These similar traits are due to the genetic material that children inherit from their parents. As humans we are sometimes fortunate enough to have three or four generations sitting in a room at one time, and we can see the similarities from generation to generation. But how much do you look like your ancestors from 100 generations ago, 1000 generations ago or more? How much of your DNA did you inherit from those ancestors? What traits do you share with them? Model 1 – Family Characteristics 1. Model 1 is a family tree. Circle the original parents of the family. 2. How would you describe the organisms in the second row of Model 1 that are connected to the parents by a line? they are the kids 3. Identify the three members of the family that “married in” by placing a star next to their figures in Model 1. 4. How are the organisms in the third line related to the organisms in the first line? they are the grandkids of the first row Evidence for Evolution 1 5. Consider the third generation of organisms in Model 1. a. How many of the organisms in the third generation exhibit one or more traits identical to one of the grandparents? 3 of them show traits like the grandparents b. How did these traits get passed on through the generations from parent to offspring? traits passed from parents through DNA 6. Consider the third generation of organisms in Model 1. a. How many of the organisms in the third generation exhibit one or more traits that are not shown in one of the grandparents? 2 of them have new traits not in grandparents b. Describe two methods by which these traits may have been introduced into the family tree. maybe from genetic mutation or married in parent 7. In Model 1, which line of offspring shares the most traits with the parent organisms in the first line, the children or the grandchildren? Support your answer with evidence from Model 1. the children have more traits like the parents 8. In Model 1, which line of offspring shares the most DNA with the parent organisms in the first line, the children or the grandchildren? the children have more DNA in common 9. Where did the original parent organisms in the first line in Model 1 get their traits? the original parents got their traits from their parents (grandparents) 2 POGIL™ Activities for High School Biology Model 2 – Forelimb Similarities Human Dog humerus Bird Whale humerus humerus Radius and Ulna wrist humerus Radius and Ulna Radius and Ulna fingers Radius and Ulna wrist wrist wrist fingers fingers fingers Number of Bones Found in the Forelimbs of Selected Animals Bone Name and Position Human Dog Bird Whale Humerus—closest to body 1 1 1 1 2, separate 2, separate 2, separate 2, separate Carpals (wrist)—2nd joint 8 6 1–2 6 Metacarpals and Phalanges (fingers)— farthest from body 5 5 3 5 Radius and Ulna 10. Label the bones in each animal forelimb in Model 2. 11. List the variety of ways in which the organisms in the table use their forelimbs. humans use for grabbing, dogs for walking, birds for flying, whales for swimming 12. Model 2 shows several homologous structures. These are limbs or body parts that are similar in structure due to shared ancestry, but that may be or may not be similar in function. a. List two or more similarities in the bone structure of the four animals shown. all have humerus and radius/ulna, bone pattern is same Evidence for Evolution 3 b. List three or more differences in the bone structure of the four animals shown. different sizes, shapes, and number of carpal bones 13. Describe the location of the “blue print” that determines the structure of each of these forelimbs as the organism develops from embryo to infant. the blue print is DNA in the embryo 14. What do the similarities among the forelimb bone arrangement of these diverse animals imply about their ancestry? it shows they have common ancestors 15. Which two animals in Model 2 would you predict have the most DNA sequences in common? Explain. human and dog probably have the most DNA in common Read This! Extensive research has been done to find similarities and differences in the DNA sequences of different animals. This work is very difficult and time consuming, but it can help biologists determine the evolutionary ancestry of a species. For example, when investigating the human genome, biologists found that about 99.5% of the DNA sequences among humans are the same. Considering the wide variety of traits in the human population, we are a lot more similar than we are different. Humans share approximately 96% of their DNA sequences with chimpanzees, 85% with mice, and 75% with chickens. 16. Study the table below. Organism Pair Percentage of DNA Similarity A–B 97 A–C 85 A–D 50 a. To which organism, B, C or D, is organism A most closely related? Support your answer. A is most like B because it has 97% same DNA b. Which pair of organisms in the table is least closely related? Support your answer. A and D are least related at 50% c. Which pair of organisms most likely shares a recent common ancestor? Support your answer. A and B are most likely to have a common ancestor 4 POGIL™ Activities for High School Biology 17. Suppose another organism, organism X, is discovered. Suggest how scientists would use DNA comparison to classify organism X? compare the X DNA with others and see which one it’s closest to Evidence for Evolution 5 Extension Questions 18. Refer to Model 2. Study the bone arrangement in the bird and whale. Propose an explanation for the similarity of elongated bone arrangement in the lower parts of the forelimb (metacarpals and phalanges), given the differences in the animals? both bird and whale use those bones for different things but came from same ancestor 19. Thinking about how traits are inherited and considering the similarities in bone structure among the various animals in this activity, what might you expect to find if you compared the development of embryos among the organisms used in this activity? embryos would probably look kinda similar at early stages 20. Thinking about how traits are inherited, how would you explain the close similarities between the make-up of the oxygen-carrying molecule hemoglobin in organisms as diverse as birds, horses, gorillas, and humans? they all need oxygen so the molecule stayed similar through evolution 6 POGIL™ Activities for High School Biology