A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true?

A) The amount of available food may have increased.

B) The number of predators may have decreased.

C) The squirrels of subsequent generations should show greater levels of genetic variation than previous generations, because squirrels that would not have survived in the past will now survive.

Choose correct combination,

#Question id: 11396

#Unit 9. Diversity of Life Forms

Carl Woese and collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?

#Question id: 11397

#Unit 9. Diversity of Life Forms

Which statement about the domain Archaea is false?

#Question id: 11398

#Unit 9. Diversity of Life Forms

Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments?

#Question id: 11399

#Unit 9. Diversity of Life Forms

The thermoacidophile, Sulfolobus acidocaldarius lacks peptidoglycan. What is likely to be true of this species?

1. It is a bacterium.

2. It is an archaean.

3. The optimal pH of its enzymes will lie above pH 7.

4. The optimal pH of its enzymes will lie below pH 7.

5. It could inhabit certain hydrothermal springs.

6. It could inhabit alkaline hot springs.

#Question id: 11400

#Unit 9. Diversity of Life Forms

What is the primary ecological role of prokaryotes?

#Question id: 11401

#Unit 9. Diversity of Life Forms

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leafʹs nonliving, waxy covering, while inhibiting the growth of

other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, it causes a fatal disease in the plant. Once the plant dies, the bacterium

and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that

apply.

1.  nutrient recycler          2.  mutualist            3.  commensal              4.  parasite          5.  primary producer