BEP 210A - Epic of Evolution

Midterm Exam - March 17, 2000

Name __________________________

This exam is closed book, closed notes. You have 1 hour. Answer 15 of 18 questions in Part and 4 of 6 in Part II. Write all of your answers on these pages. Good luck!

Part I. (60 pts.): Answer 15 of the following 18 questions in a few sentences. Please cross out the 3 that you don't do. Each of these questions is worth 4 pts.

1) Which of the following objects make up which other ones: neutrons, atoms, quarks, nuclei, electrons, protons? What force holds each composite object together?

2) Put the following three milestones of the Big Bang in chronological order: nucleosynthesis, proton-antiproton (and neutron-antineutron) annihilation, baryogenesis. Once you have ordered the processes, explain how the first process set the stage for the second; and similarly explain how the second process set the stage for the third.

3) How do we know that distant galaxies are moving away from us? Give an example of an analogous effect in everyday life (involving sound).

4) Tell what happened at the period of electron-positron annihilation (about 1 second after the Big Bang). Explain why it could not have happened earlier.

5) What is a quasar and how does it work? Why are all the quasars that astronomers have discovered far away from the earth?

6) What was the "T-Tauri event" in the formation of the solar system? What effect did it have on the composition of the planets? Why is a T-Tauri event much faster than the normal energy producing processes that make the sun shine now?

7) What factors contributed to the early melting of the Earth?

8) Describe how the Moon formed?

9) What are rising plumes and sinking slabs?

10) Why is the Earth like a pot of soup on the stove?

11) Why are there ocean fossils here in St. Louis?

12) Why do volcanoes occur at subduction zones, and why are the eruptions explosive?

13) Thinking of an RNA molecule as a paper-doll chain:

a) Which paper-doll component(s) represent covalent bonds?

b) Which are involved in base-pairing?

c) How is base-pairing involved in generating RNA shapes?

d) How is base-pairing involved in RNA replication?

14) In the switch over from an RNA World to present-day life:

a) Which class of macromolecule came to carry the instructions?

b) Which class of macromolecule came to catalyze biochemical reactions?

c) Which class of macromolecule came to be directly involved in translating the genetic code?

d) How is base-pairing involved in translating the genetic code?

15) Describe why an enzyme changes its shape as the consequence of "pocket occupancy."

16) a) During photosynthesis, where are the electrons located that interact with

photons?

b) During gene regulation, where in the DNA are the nucleotides located that

interact with transcription factors?

c) During signal transduction cascades, how is ATP used to generate shape

changes?

d) During embryology, where is the first gradient found?

17) Some of the following statements can be used to document that all present-day life is genetically descended from a common ancestor - some do not yield this conclusion. Circle those that can be used.

a) All modern organisms are aware.

b) All modern organisms use the same codons.

c) Shapes were generated by RNA molecules in the early "puddles."

d) ATP-binding domains are the consequence of bricolage.

18) Describe the essential features of the cell cycle.

Part II: (40 pts.) Answer 4 of the following 6 questions with a paragraph or so. Each is worth 10 points. Please cross out the two that you do not do. Use the other page side if necessary.

1) Explain how a star like the sun shines. Your explanation should include the following:

a) a statement of what the "raw materials" and "end products" are. (You do not need to list the individual reactions along the way.)

b) the role of each of the four forces.

c) the reason why the energy-releasing process only starts when the temperature gets high enough.

2) What happened at the period of "decoupling" and why? How is the cosmic microwave background related to decoupling? What significance does decoupling have for the condensation of galaxies and stars?

3) Explain the ways in which the Earth cools down, eventually losing its heat to space.

4) Explain the difference between the way ocean crust and continental crust is formed.

5) Explain (flesh out) what is meant by the following: mutations basically run new protein shapes up a flagpole, and natural selection is equivalent to asking whether anybody salutes.

6) Explain (flesh out) what is meant by the following: embryology expanded on the unicellular idea of regulating gene expression in time to include regulating gene expression in space.