L2
讲座
1. What is the main purpose of the lecture?
To explain the function of stromatolites in Earth’s earliest ecosystems
To discuss the characteristics of the bacteria that form stromatolites
To discuss a possible cause for the decline of stromatolites
To examine a disagreement over which came first, stromatolites or thrombolites
2. What opinion does the professor express about stromatolites?
Stromatolites illustrate an important concept in Earth science
A popular theory about the origin of stromatolites is probably wrong.
Human activity is having a negative impact on living stromatolites.
The literal meaning of the word “stromatolite” does not accurately describe a stromatolite.
3. Why does the professor mention dinosaurs?
To suggest that dinosaurs and stromatolites may have declined for the same reason
To suggest that the decline of stromatolites may have played a role in the dinosaur extinction
To emphasize how dramatic the decline of stromatolites was
To emphasize the difference between a “decline” and an “extinction”
4. What point does the professor make about the salt content of Shark Bay?
The presence of stromatolites has led to an increase in the salt content of the bay.
Shark Bay’s high salt content helps protect the bacteria that produce stromatolites.
Recent increases in the salt content of Shark Bay have stopped the growth of stromatolites there.
Shark Bay has a higher salt content than the ocean had billions of years ago.
5. According to the professor, what is one difference between stromatolites and thrombolites?
Only stromatolites are composed of sediments.
Only stromatolites form in shallow water.
Only stromatolites require the presence of bacteria to form
Only stromatolites consist of well-ordered layers.
6. What do the results of the researchers’ experiments with stromatolites and foraminifera suggest?
Foraminifera behave differently in the laboratory than they do in the wild
Foraminifera stimulate the growth of the bacteria that produce stromatolites
Foraminifera help protect stromatolites from various kinds of threats.
Foraminifera movement can cause structural changes in stromatolites.
