Due

1. what are primary and secondary succession?

2. how do communities change over time?

3. why do successions occur?

4. do ecosystems return to “normal” following a disturbance, such as a natural disturbance or a human-caused disturbance?

80 pts the type of cloud shown here may produce heavy rainfall. this type of cloud most likely occurs in an area of the sub-saharan that is a) often dry. b) often wet. c) very windy. d) usually cool.

Which of the following scenarios is an example of the bottleneck effect? answers a in south africa, much of the afrikaner population is descended from a small number of dutch colonists. in this population, this is an unusually high frequency of pseudoxanthoma elasticum (pxe), an elastic tissue disorder. b four white-tailed deer are introduced to a park in finland. thirty years after their introduction scientists compare the genes in the population and find that there is no variation. c during the industrial revolution, london's air became filled with soot. as a result, birds started eating more of the lighter moths because they were easier to spot than their darker counterparts. over time, the moth population changed so that there were more darker moths than lighter ones. d 10% of the population of american alligators in an area have the recessive trait albinism. a massive flood results in the death of 80% of the population. of the remaining population, 60% have the recessive trait of albinism.

Which of the organisms listed below performs nitrogen fixation? a. legumes b. plants c. bacteria d. fungi