Ecology

2.a) The growth curves for species B in group I and for species A in group II (shaded columns) have been plotted on the template. Use the template to complete an appropriately labeled line graph to illustrate** the growth of species A in treatment group I and species B in treatment group II (unshaded columns).

2.b) As shown in the table, the student established treatment group II with 5 individuals of each species. Provide reasoning for the reduced initial population sizes.

2.c) The student claims that species A and B compete for the same food source. Provide TWO pieces of evidence from the data that support the student’s claim.

2.d) Predict TWO factors that will most likely limit the population growth of species A in treatment group I.

2.e) Many protists contain an organelle called a contractile vacuole that pumps water out of the cell. The student repeated the experiment using a growth medium with a lower solute concentration. Predict how the activity of the contractile vacuole will change under the new experimental conditions. Justify your prediction.

5.a) A characteristic of a community that makes a species invasive in that community but not invasive in a different community is the absence of natural predators or competitors in the invasive community.

5.b) Removing species PP1 will have a greater effect on community B than on community A because PP1 is the only producer in community B, while community A has multiple producers. The removal of PP1 in community B will lead to a collapse of the food web.

5.c)

5.d) Human activities that add toxins to the soil could change a community with many species at each trophic level, such as community A, into a community with few species at each trophic level, such as community B, because the toxins could kill off many of the species in the community. This would reduce the biodiversity of the community and lead to a less complex food web.

3.a) Describe the effect of increased biodiversity on the resilience of an ecosystem in a changing environment.

3.b) Justify the scientists’ selecting 5°C as the lowest temperature and 400 μatm as the lowest CO2 level in their study of sand lance embryo survival.

3.c) State a null hypothesis for the experiment.

3.d) The scientists claim that a reduction in the population size of the Ammodytes sand lances will affect the stability of the entire coastal ecosystem. Provide reasoning to support the scientists’ claim.