Beavers are considered a keystone species in the U.S. because of their extensive dam-building activities and their role creating riparian habitat. They generally feed on leaves, soft inner bark, and young shoots of trees (and not on animals).  Explain why these characteristics would result in the keystone role of beavers in their ecosystem. Select only ONE answer choice, the best answer.  

At ASU graduation during the festivities, your great aunt brings a potato salad to share.  Your auntie places the potato salad on a picnic table in the hot sun at 1:00 pm – where it continues to sit all day.  This potato salad is starting to look funny and it smells quite bad!  With your special training in bacterial population ecology, you estimate the population size of E. coli bacteria in this dish to be 300,000 cells at 4:00 pm and 600,000 cells at 5:00 pm.  Able to replicate in one hour,  how many bacteria will be there by 6:00 pm?  (One growth cycle). Select only ONE answer choice.  Hint: because this is a population has been growing all day, it may be running out of resources – hence the logistic growth equation is probably appropriate.  We will assume a carrying capacity of 2,000,000 cells.

The Midas cichlid species complex is a group of fish species found in a young and small volcanic crater lake in Nicaragua. Researchers found that this lake (Lake Apoyo) was seeded only once by the ancestral species Amphilophus citrinellus, the most common cichlid species in the area.  They found that a new species (Amphilophus zaliosus) evolved in Lake Apoyo from the ancestral species (A. citrinellus) within less than ∼10,000 years.   Both species inhabited this lake during this same time period.  Finally,  they demonstrated that two species in Lake Apoyo are reproductively isolated; and both different in outward phenotype and their preferred ecological niche in the lake.  This is an example of what kind of speciation?

The African great lakes (including Tanganyika and Malawi) are famous for their diversity of cichlid fish species.  These fish have radiated out into a whole complex of species – with diverse coloring and behaviors and specialized adaptation to different niches found in the lakes.  They are a famous example of sympatric speciation.  In their native lakes, these species rarely mate, but in an artificial setting (such as aquariums) different species are able to successfully reproduce together (but only when given no other choice).  Behavioral factors and sexual selection may be important.  Which reproductive barriers are most likely involved in their speciation in nature?  Choose all that apply (multiple answer question)

In a two-point test cross GgWw x ggww what proportion of the offspring will be Yellow and smooth? (a Mendelian experiment with pea-plant crossing). G_ = yellow gg = green W_ = smooth ww = wrinkled

A population of snakes that is at Hardy-Weinberg equilibrium has the following genotype frequencies:   Phenotype:                         green skin                    yellow skin                                                  Genotype:                         BB    or   Bb                           bb Phenotype frequency:           0.96                               0.04 What is the frequency of p (B) and q (b)?

Directions: The following question is based on the food web (below). Which organism acquires energy from both producers and consumers? Select only ONE answer choice. 

Given the observed genotype frequencies below, what would the expected frequencies be under Hardy-Weinberg? *Hint: first calculate ‘p’ and ‘q’ then determine the predicted values for the genotype frequencies under Hardy-Weinberg. AA Aa aa 0.3 0.1 0.6

You are given the following information about a population: There are two alleles, C and c C is dominant to c C codes for blue hair and c codes for white hair The frequency of the c allele is 0.6 The population is comprised of 100 individuals. Assuming the population is in Hardy-Weinberg equilibrium, how many individuals have blue hair?

Is this population at Hardy-Weinberg equilibrium? AA Aa aa 0.4 0.51 0.09 Hint: calculate the allele frequencies: p(A) and q(a) and then remember that under Hardy Weinberg equilibrium p2+ 2pq +q2= 1.  With the allele frequencies calculated you can come up with the expected frequencies for AA, Aa, and aa under Hardy-Weinberg.  If these expected frequencies match the frequencies you actually see above it is in HW equilibrium