7. Indicate which stage of mitosis is occurring in each of the images above and describe what is happening using the words: chromosomes, centrioles, nucleus, and spindle fibers.
A
B
D
C

1. in what ways have non-native species been beneficial? 2. what are some of the hypotheses for the collapse of honeybee colonies? 3. distinguish between regional and functional extinction. 4. why is it difficult to measure background extinction rates? 5. what three factors are most important in causing extinction rates to climb?