AP BIOLOGY Student Exploration: Embryo Development Gizmo

Student Exploration: Embryo Development Vocabulary: Blastula, Carnegie stages, differentiation, ectoderm, embryo, embryology, embryonic stem cells, endoderm, fetus, gastrula, inner cell mass, mesoderm, morula, neurula, primitive streak, trilaminar disk, zygote Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. The images below show embryos of different species at different stages of development. Label the images below with 1-4 from least developed to most developed. A 4 B 1 C 3 D 2 2. Which image above do you think is a human? Explain. Example B is human because its smaller Gizmo Warm-up Embryology is the study of the development of embryos from a single cell to a multicellular fetus. In the Embryo Development Gizmo, you will compare the development of different animals and learn the details of mammalian development. To begin, be sure the COMPARE tab is selected. 1. What do the images have in common? They have a similar shape Click on the check box to turn on Scale bars and labels. You are observing the zygotes, or fertilized single cells, of five animals. 2. At this point, are you able to tell which animal is which? no Explain? Its to small to tell Activity A: Comparative embryology Get the Gizmo ready: • Make sure the COMPARE tab is selected and the Developmental stage slider is on stage 1. • Turn off Scale bars and labels. Introduction: Comparative embryology compares embryos of different species to gain insight into how they are related. To provide a framework for this comparison, embryologists divide this process into 23 Carnegie stages. You will look at seven of these stages in this activity. Question: Can we use comparative embryology to determine the relatedness of species? 1. Challenge: Drag the labels to the embryos you think they belong to. Fill in the first row of the table below with your guesses. Then, move the Developmental stage slider one position to the right, to Carnegie stage 4. Rearrange your labels if necessary and fill in the next row of the table. Continue until you get to stage 23. Don’t turn on the Reveal answers check box until the end. (Note: Your guesses may change as you go through the stages. Don’t worry, they won’t be graded - this is just for fun!) Stage A B C D E 1 Fish Chicken Mouse Human Frog 4 8 13 frog Fish 16 fish Frog 20 23 2. Reveal: Click Reveal answers. A. Did you guess correctly in the end? Carnegie stage 8 B. At which stage were you able to tell which was which? The chicken and the human were pretty easy Explain: they were obvious in the second stage