Listen to part of a lecture in a biology class.
- What is the lecture mainly about?
- A. The discovery of a previously unknown trace metal.
- B. The role trace metals play in carbon cycling.
- C. Ways that living organisms rid themselves of trace metals.
- D. Ways that zinc interacts with carbon dioxide.
- What does the professor imply about the conversion of carbon dioxide molecules in plants?
- A. It is an unusually complex chemical process
- B. It only takes place in full sunlight
- C. It proceeds slowly when cadmium is present
- D. It is regulated by an enzyme that may contain zinc
- According to the professor, why is it surprising that many marine plants are able to survive near the surface of oceans?
- A. Weather conditions near the surface disrupt certain life processes.
- B. The salt content of surface waters is constantly changing.
- C. Surface waters contain low quantities of zinc.
- D. Surface waters absorb large amounts of carbon dioxide.
- According to the professor, what important function do diatoms serve?
- A. They alter cadmium so it is less toxic to humans.
- B. They help cycle zinc in places where it is scarce.
- C. They distribute carbon throughout the ocean.
- D. They remove cadmium from the ocean floor.
- What point does the professor make when she talks about cadmium being poisonous to humans?
- A. That cadmium and zinc can serve a similar function in plant enzymes.
- B. That both cadmium and zinc are rare in plant enzymes.
- C. That most trace metals are poisonous to humans.
- D. That cadmium does not serve any biological purpose.
- The professor states that the discovery of an enzyme containing cadmium is important. What are two reasons that this discovery is important?
[CHOOSE 2 ANSWERS]
- A. It may lead to the discovery of new enzymes that use other trace metals.
- B. It may explain the ocean’s increased level of carbon dioxide.
- C. It may explain the scarcity of some elements in the ocean.
- D. It may help scientist better understand global warming.
B D C C A AD