1. Take out your Clocks in Rocks for check-off Prepare for a warm-up!
BES 10/30 and 10/31
Take out your Clocks in Rocks for check-off
Prepare for a warm-up!

2. Warm-Up 10/30 and 10/31
You find a sample of 10 radioactive Uranium atoms near an old dinosaur bone. Draw ten circles in your lab book to represent these atoms.
What would they look like after one half life, when half have turned to Lead?
Draw them after two and three half-lives!

3. Part 2
You measure a fossil that has a ratio of 25% Uranium and 75% Lead. How old is it?
If there were 10 grams of Uranium to start with, how many are left after 3 half lives?

4. Learning Targets
I can calculate the age of a fossil using Radiometric Dating
I can explain how embryos and body structures provide evidence for evolution

5. Another explanation of Carbon dating

6. Radiometric Dating Practice
Pink Worksheet
PHET simulation (extra credit)- only if Clocks in Rocks and pink worksheet are done

7. Check Up 100% C-14 0% N-14 50% C-14 50% N-14 25% C-14 75% N-14
How old would the bottom row of fossils likely be?
How old would the top row of fossils likely be?
(Half-life of C-14 is 5730 years)

8. Evidence For Evolution
How do we know evolution happens?
Fossil record
a. Relative and radiometric dating
DNA comparisons- next unit
Body structures
Comparing embryos
Antibiotic resistance and Viruses

9. Form Follows Function
Body structures of organisms have to be a perfect fit for their environment or they don’t survive.
Organisms “unfit” will die off by natural selection
The perfect fit of organisms is evidence that natural selection and evolution occur

10. Homologous Structures
A second piece of evidence for evolution is Homologous Structures
Body structures in organisms that can be explained by a common ancestor.
Ex: Whales, humans, birds, and all vertebrates have the same “hand” bones
The bones have taken on different shapes to fit the purpose they are used for!

11. Similarities: number and location of bones Differences: shape of bones
Why? The animals have adapted to survive in their environment (see the verbs above each picture!)
Homologous Structures Berkeley Website?

12. Vestigial Structures
Some organisms have traces of homologous structures that they no longer use
Ex: human appendix
Our grass/leaf eating ancestors needed a large appendix to digest lignin
We have a smaller version left over!

13. Human Vestigial Structures
We inherited these useless characteristics from our mammal ancestors!

14. Embryology Activity Where do these body structures first come from?
Put the correct embryo in the correct stage for the correct organism.
Discuss with your teammates, come up with the solution.
Flag me down and I’ll tell you how many you have correct.

15. Embryology Activity Which was the easiest? Which was the toughest?
What do the three most similar organisms have in common?

16. Comparative Embryology
Embryos of diverse organisms look very similar!

17. Comparative Embryology
The same groups of embryonic cells develop in same order and in same patterns
Groups of cells produce homologous structures
We must have inherited the same directions (DNA) from a common ancestor!
Snapping Turtle Embryo
Cat Embryo

18. Due Next Time Pink Radiometric Dating Worksheet
PHET Simulation (Extra Credit)