“Life’s Greatest Miracle” Video Worksheet Name: Refer to the Video on Demand link to this video in the Cell Division Lesson. http://video.pbs.org/video/1841157252/ or Miracle of Life Part 1 www.youtube.com or http://youtu.be/vR75Y3G8PHA Answer the following questions about the video using information from the video. Submit your worksheet to the dropbox. 1. You began life as a single cell. By the time you reach adulthood, your body consists of about how many cells? 2. The adults on the beach are all busy trying to do one thing, even though they may not realize it. What are they trying to do? 3. DNA has “run the show” for more than four billion years. Why? What ability does DNA have that has made it so successful? 4. How do bacteria reproduce? Use the name that the narrator gives for the process. 5. Why would it be dangerous for humans to reproduce in the way that bacteria do? What example does the narrator give? 6. What method of reproduction is used by 99.9% of all organisms more complex than bacteria? 7. How are the offspring of organisms using the method in #6 different from bacteria? (This property gives survival of the fittest a definitie advantage.) 8. How many new sperm does an average man churn out every second? 9. What is the process for making sperm or eggs called? 10. What are the names of the man and woman in the film? 11. At what age or stage of the woman’s life did her body develop all its eggs? 12. At age 31, about how many eggs does the woman have left? 13. The egg that has been expelled from the ovary has everything it needs to survive except for one thing. What is that one thing? 14. When a man ejaculates, about 1 teaspoon of semen is released. About how many sperm are in that one teaspoon? 15. What is it about the vagina that makes it inhospitable to sperm? 16. Once a sperm reaches the egg, it must break through a thick protein shell in which the egg is encased. What is the thick protein shell called? 17. What percent of fertilized eggs fail to develop? 20. How long after after the sperm enters the egg does the first cell division take place? 21. How many days does the ball of cells that will become the baby take to arrive in the uterus? 22. The ball of cells, called the blastocyst, is in grave danger once it enters the uterus. Why is it in danger and how does the blastocyst overcome this danger? 23. What is the name of the milestone event that occurs 2 weeks after conception when the cells of the blastocyst organize themselves into an embryo? 24. How many layers of cells form during this process in #23? 25. Give an example of an organ or other body part that each layer will give rise to. a. Lower layer: b. Middle layer: c. Top layer: 26. What is responsible for the fact that there are different types of cells that make up the body with different types of jobs? 27. What is the name of the gene, found on the Y chromosome, that confers maleness? The narrator says that this gene functions only once in a lifetime, late in the 6th week of embryonic development. 28. How wide must the cervix become to allow for the birth of a baby? (This is the tiny passageway that once allowed the entrance of a single file of sperm.) 29. How and why is the human brain and pelvis different in size or shape from that of an ape? 30. Why was death a common outcome of of the birthing process before the rise of modern surgery?