Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Name: _______________________ Evidence for Evolution Much evidence has been found to indicate that living things have evolved or changed gradually during their natural history. The study of fossils as well as work in embryology, biochemistry, and comparative anatomy provides some of the evidence for evolution. PART 1: HOMOLOGOUS STRUCTURES Carefully examine the drawings of bones in Figure 1. Notice that all the limbs, whether wins, arms, legs, or flippers, are built upon the same basic structure. These structures form in similar ways during embryonic development and share similar arrangements, but are somewhat different in form and function. We call these structures homologous structures. Figure 1 1. Examine the relative size, shape, number and position of the bones. Then, in the table below, identify the body part shown for each organisms and describe the function of that body part. Animal Human Whale Cat Bat Bird Whale Body Part Function 2. How are the body parts from the Figure 1 similar? How are they different? List two or more similarities or differences. Similarities Differences 3. How does the arm of a human and the flipper of a whale what show evidence of an evolutionary relationship? __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ PART 2: ANALOGOUS STRUCTURES Some unrelated animals have organs with similar functions, yet are very different in both structure and form. These types of structures are called analogous structures. Figure 2 4. Do the wings have similar or different structures? Hint: Are they made of the same “materials?” Explain your answer. __________________________________________________________________________ __________________________________________________________________________ 5. Do the wings have similar or different functions? Explain your answer. __________________________________________________________________________ __________________________________________________________________________ 6. Does the structure of the wings suggest that there is a close evolutionary relationship? Why do you think this? __________________________________________________________________________ __________________________________________________________________________ PART 3: VESTIGIAL STRUCTURES Gradual changes have occurred throughout time and have in some cases, reduced or moved the function of certain body structures and organs. Organs or structures that remain in an organism but have lost their function and become reduced in size are called vestigial structures. The penguin’s wings and the leg bones of snakes are examples of this phenomenon. The cave fish and minnow shown in Figure 3 are related, but the cave fish is blind. Minnow Cave Fish Figure 3 7. Explain why the cave fish’s eyesight is NOT an important adaptation to life in a cave. __________________________________________________________________________ __________________________________________________________________________ 8. Does the appearance of the cave fish and minnow suggest any common ancestry? Give an example. __________________________________________________________________________ __________________________________________________________________________ 9. Read the list of human vestigial structures below. Suggest a possible function for each part (think about what modern day animals might do with these structures as some may still have them) and explain why it might have become vestigial in humans. The first one has been done for you as an example. Structure Ancestral Function and Use in the Wild Why Vestigial Now? Appendix Aided in digestion of grasses, leaves, and other foliage when our ancestors were herbivores. Humans eat less raw plant food material now and often cook their food. Food is more easily digested and so the appendix is less necessary. Coccyx (tail bones) Assists in balance and mobility as a tail. Muscles to move ears The ability to change ear position to pick up noises from other animals in the area. Goose bumps when under stress Reflex to raise body hair to make the body look larger and more intimidating to predators. Wisdom teeth Used to grind down raw plant tissue and typically appear later in life. Possibly used to replace teeth lost or eroded by a coarse diet which may have included some dirt and sand. PART 4: CYTOLOGY (Study of Cells) All organisms—big and small—are made of cells. Cells consist of membranes, genetic material, proteins, fats, carbohydrates, salts, and other substances. Look at the picture of a typical animal and plant cell below. Notice that only three structure (in capital letters: cell wall, centriole, and chloroplasts) are unique to either plant or animal cells. Figure 3 10. What is inside the nucleus of a plant and animal cell? __________________________________________________________________________ 11. Do bacteria have a nucleus? __________________________________________________________________________ 12. What do you this means (with regards to #11) in terms of when bacterial first appeared on Earth? Did they come before or after plant and animal cells? How do you know? __________________________________________________________________________ __________________________________________________________________________ PART 5: DNA DNA, our genetic code, is nearly universal in eukaryotes and prokaryotes. Anthropologists compare the differences in DNA to determine the period in which the splitting of two species from an ancestor occurred. This is based on the fact that harmless DNA mutations can be passed from parent to offspring and will build up from generation to generation. Generally, the greater the amount of time that has passed since two species diverged from a common ancestor, the more different their DNA will be. Measuring the differences in DNA between species can be used to tell how long ago they split from a common ancestor. The chart below shoes the percentage difference between the DNA of several primate species. Examine the chart and answer the questions based on the evidence presented. Species Compared Human & Gorilla Human & Chimpanzee Gorilla & Chimpanzee Human & Orangutan Gorilla & Orangutan Chimpanzee & Orangutan Percent Difference in DNA 1.4% 1.2% 1.2% 2.4% 2.4% 1.8% 13. What is the job of DNA? __________________________________________________________________________ __________________________________________________________________________ 14. Which are more closely related? a. A chimpanzee & orangutan OR a human & orangutan? ____________________________ b. A human & chimpanzee OR a gorilla & chimpanzee? ____________________________ c. ____________________________ A human & gorilla OR a gorilla & orangutan? 15. If the DNA is very similar, what does that mean for how these related organisms function, behave, etc. in comparison to each other? __________________________________________________________________________ __________________________________________________________________________ PART 6: EMBRYOLOGY As adults, humans, fish, pigs, chickens, and salamanders are very different animals. But, surprisingly, they look very similar in their early stages of development. Chickens and eggs even retain many similarities until they are born! As Darwin realized, such developmental resemblances hint at having a common ancestor. Different animals develop along similar pathways because they have all inherited the same genes for building limbs or eyes or heads. In fact, swapping the gene that triggers eye development in one animal with the corresponding gene from another animal has little effect—it’s the same gene! Differences arise among various species because of changes that affect when and where genes get activated during development. Ultimately, those variations in timing are the biggest differences between fish, chickens, pigs, and humans! Figure 5 16. What are some common characteristics that ALL the animals share at some point in their development? __________________________________________________________________________ __________________________________________________________________________ 17. Looking at the developmental patterns for the animals above, which two animals seem to be the most closely related? __________________________________________________________________________ 18. What did you choose the two animals that you did in #17? Explain what you see. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ 19. Why do you think that humans, cows, rabbits, and pigs look similar for so long? What do they have in common compared to other animals? __________________________________________________________________________ __________________________________________________________________________