Polar bear evolution
1. What is the main purpose of the lecture?
- A To compare the behaviors of three different bear species
- B To examine changes to the habitat in which polar bears live
- C To discuss recent insights into polar bear evolution
- D To illustrate a new method of DNA analysis used in climate studies
2. Why did the professor mentions use mitochondrial DNA for testing instead of nuclear DNA?
[CHOOSE 2 ANSWERS]
- A Mitochondrial DNA has a more stable structure than nuclear DNA has.
- B Mitochondrial DNA has a shape that is more easily identifiable than that of nuclear DNA.
- C Mitochondrial DNA is present in larger quantities in cells than nuclear DNA.
- D Mitochondrial DNA analysis is a better-understood research tool than nuclear DNA analysis
3. What point does the professor make about brown bears?
- A They now compare with polar bears for food- and territory.
- B They are the ancestors of polar bears.
- C They face the same environmental threat as polar bears.
- D Their jawbones can be easily distinguished from those of polar bears.
4. According to the professor, what do researchers believe about the Svalbard islands?
- A Polar bears first came into existence as a species on the islands.
- B The separate islands were once joined together in a single large landmass.
- C Interbreeding between polar bears and a species of brown bear occurred on the islands.
- D The islands provided a refuge for polar bears during an ancient warming period.
5. What does the professor imply when she discusses the current warming period?
- A The consequences of the current warming period will not be as serious as most scientists believe.
- B The current warming period is progressing more slowly than previous warming periods.
- C Arctic temperatures today are similar to temperatures during previous warming periods.
- D The fast pace of the current warming period will threaten polar bears’ long-term survival.
6. Why does the professor imply when she says this: 【音频缺失】
- A The size of the grizzly bear population will soon stabilize.
- B The future of the polar bear as a distinct species might be at risk.
- C Hybridization has already diminished the polar bear population within a short period of time.
- D Hybrid species do not adapt well to sudden changes in the environment.