Evolution Evolution Online Activities Radioactive Dating Game Lab ...

Name: ________________________ AP Biology - Unit 8: Evolution Evolution Online Activities Radioactive Dating Game Lab Purpose: You will use the radioactive decay rate and original-daughter element ratios of carbon-14 and uranium-238 to determine the ages of different objects. Procedure: 1. 2. 3. 4. 5.

Go to: http://phet.colorado.edu/en/simulation/radioactive-dating-game Load PhET Radioactive Dating Game. Click on the “Decay Rates” tab. Select Carbon-14. Using the graph, the estimated half-life for C-14 is _________ years. Move the bucket slider all the way to the right. This will place 1000 C-14 atoms onto the screen. (a) Click on the Start/Stop to stop the C-14 decay. Click on Reset All Nuclei. (b) Click on the Start/Stop to start the C-14 decay. Stop the decay as you get close to one half-life. (c) Use the Step button to stop decay at one half-life. • After 1 half-life, how many C-14 atoms of the 1000 original remain? _______ • Use the Start/Stop and Step buttons to reach two half-lives. After two half-lives, how many C-14 atoms remain? ________ • What fraction of the C-14 atoms present at 1 half-life remain after 2 half-lives? _______ (d) Use the Start/Stop and Step buttons to reach three half-lives. After three half-lives, how many C-14 atoms remain? ________ • What fraction of C-14 atoms present at 2 half-life remain after 3 half-lives? _______ 6. Repeat Steps (a) to (d) with Uranium-238. • Estimated half-life for U-238 is _________ years. • After 1 half-life, how many U-238 atoms of the 1000 original remain? _______ • What fraction of the U-238 atoms present at 1 half-life remain after 2 half-lives? _______ • What fraction of the U-238 atoms present at 2 half-life remain after 3 half-lives? _______ 7. Based on the results above, explain the meaning of the word “half-life” in one complete sentence.

8. Click on the “Measurement” tab. 9. Under Probe Type, select Uranium-238 and Objects. Under Choose an Object, select Rock. 10. Click on Erupt Volcano. Let the simulation run until you reach 1 half-life. What percent of the original uranium remains? _________. How many years did this take? ____________ 11. Under Probe Type, select Carbon-14 and Objects. Under Choose an Object, select Tree. 12. Click on Plant Tree. Let the simulation run until you reach 1 half-life. What percent of the original carbon remains? _________. How many years did this take? ____________ 13. Explain why uranium-238 is used to measure the age of rocks while carbon-14 is used to measure the age of the tree trunk?

14. Click on the “Dating Game” tab. There are objects on the surface and in the five layers beneath the surface. There are both rocks and fossils in each layer. 15. Select the Carbon-14 detector. Move the Geiger counter to each fossil and record the percent of original in the table below. 16. On the ½ life graph, move the green arrow right or left until the percent of original matches the reading on the detector. Record your estimated age for each fossil in the table. 17. Repeat Steps 12 and 13 using the Uranium2-38 detector to estimate the rock ages. For fossils with no remaining C-14 signal, use the rock ages to estimate fossil ages in the same layer. Table: Radiometric Ages for Various Objects Measured using C14 or U-238?

Object

Percent of Original

Guessed Age

Measured Age

Animal Skull Living Tree Distant Living Tree House Dead Tree Bone Wooden Cup 1st human skull 2nd human skull Fish Bones Fish Fossil 1 Rock 1 Dinosaur Skull Rock 2 Trilobite Rock 3 Rock 4 Rock 5 18. In the space below, summarize how C-14 and U-238 dating together can be used to determine fossil ages.

Campbell Online Resources – Chapter 26 Investigation: How Did Life Begin on Early Earth? 1. Why is it not feasible to replicate the events leading to the origins of life on Earth?

2. What proportion of the molecules produced in the experiment are directly useful for the cellular metabolism and cell structure found in contemporary organisms, and what is the importance of this observation?

3. Hypothesize why clay was important in the formation of life on Earth.

4. What information is greatly lacking that prevents the solidification of a theory explaining the origins of cells similar to those existing today?

A Scrolling Geologic Record Era Precambrian

Paleozoic

Mezozoic

Cenozoic

Time Span

Major Events

New Types of Organisms Evolved

The History of Life Label the timeline below by listing the events from the activity in the correct order. earliest

most recent

Classification Schemes In the early days of biology, all organisms were classified as either ____________ or _______________. Single-celled eukaryotic organisms such as algae and Paramecium were assigned to one of the kingdoms according to whether they are ______________________ or not. __________ and _____________________ were grouped with plants, because fungi are __________________ and prokaryotes have ________________. A ________________________ scheme was devised because some organisms don't fit well into a twokingdom system of classification. The simple cells of prokaryotes set them apart in their own kingdom, _______________. Organisms in the other four kingdoms all have ______________________________. __________ are not photosynthetic, so they are given their own kingdom. The kingdom ________________ is an assortment of eukaryotes that don't fit into the other kingdoms-- mostly ___________________ organisms such as Paramecium, unicellular algae, and multicellular algae. The ______________________ scheme divides living things into two fundamentally different groups-prokaryotes and eukaryotes. New data suggests that two kinds of prokaryotes diverged early in the history of life, and thus there are actually three major categories of organisms. A new classification system assigns more significance to the ancient split by creating a level of classification larger than a kingdom--a new category called a ____________. The two domains of prokaryotes are _______________ and ______________. The domain ______________ encompasses all of the kingdoms of eukaryotes. Taxonomists are in the process of sorting out various kingdoms of prokaryotes within the domains Bacteria and Archaea, and also splitting the protists into several kingdoms within the domain Eukarya.