8. Which of the following provides the best evidence of a biodiversity crisis?
(A) the incursion of a non-native species
(B) climate change
(C) increasing pollution levels
(D) decrease in regional productivity
(E) high rate of extinction

4. Leaf thickness represents a trade-off between ______. (A) water retention and carbon dioxide absorption (B) light collection and carbon dioxide absorption (C) water retention and oxygen absorption (D) light collection and oxygen absorption (E) light collection and water retention

5. What is the only type of chemical signal that does not alter the physiology of the animal producing that signal? (A) paracrine (B) pheromones (C) neuroendocrine (D) neural (E) none of above

6. Which of the following causes populations to shift most quickly from an exponential to a logistic population growth? (A) competition for resources (B) favorable climatic conditions (C) decreased death rate (D) removal of predators (E) increased birth rate

7. Matter is gained or lost in ecosystems. How does this occur? (A) Heterotrophs convert heat to energy. (B) Photosynthetic organisms convert solar energy to sugars. (C) Chemoautotrophic organisms can convert matter to energy. (D) Matter can be moved from one ecosystem to another. (E) Detrivores convert matter to energy.

9. An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake? (A) disruptive selection (B) a genetic bottleneck (C) directional selection (D) a founder event (E) stabilizing selection

10. If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents? (A) It has double the amount of DNA as the cell that began meiosis. (B) It has one-fourth the DNA and one-half the chromosomes as the originating cell. (C) It has half the amount of DNA as the cell that began meiosis. (D) It is identical in content to another cell formed from the same meiosis I event. (E) It has half the chromosomes but twice the DNA of the originating cell.

11. Jams, jellies, preserves, honey, and other foods with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment ______. (A) are unable to swim through these thick and viscous materials (B) undergo death as a result of water loss from the cell (C) are unable to metabolize the glucose or fructose, and thus starve to death (D) are obligate anaerobes (E) are unable to reproduce then die eventually

12. Sympatric species ______. (A) are more likely than allopatric species to display character displacement (B) always show character displacement (C) are less likely than allopatric species to display character displacement (D) are unlikely to be competing (E) are more likely than allopatric species to display character displacement and likely to be competing

13. The veins of leaves are ______. I) composed of xylem and phloem II) continuous with vascular bundles in the stem and roots III) finely branched to be in close contact with photosynthesizing cell (A) only I (B) only II (C) only III (D) I and II (E) I, II, and III

14. To be useful to plants soil nitrogen must usually occur as: (A) N2 and NH3 (B) NH3 and NO3 - (C) NO3 - and N2 (D) N2 and NO2 (E) NO2 and NO3 -