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Possible Free Response Questions (FRQs) for Unit 2 Test (chapters 5,6)
Directions: You will be asked to answer two of the four questions listed below (my choice), which are weighted equally;
the suggested time is about 15 minutes for answering each question. Where calculations are required, clearly show
how you arrived at your answer. Where explanation or discussion is required, support your answers with relevant
information and/or specific examples.
1. Extinction is a natural occurrence, though many scientists claim that Earth is currently entering its sixth mass
extinction event.
a. Use the data below to answer the questions that follow. For each calculation, show all work.
Historical annual extinction rate based on fossil record: 1 species per 1 million extant
species
Species that have gone extinct worldwide between 1970 – 2004:
58 fish, 9 birds, 1 mammal
There are approximately 35,000 extant fish species in the world
There are approximately 10,000 extant bird species in the world
There are approximately 5,000 extant mammal species in the world
i. Use the historical extinction rate to calculate how many years it should take for a species of bird
to go extinct.
ii. Calculate the combined extinction rate, in species per year per million, of fish, bird and mammal
species between 1970 and 2004.
iii. Using your answer from part (a) ii, calculate how many times greater the 1970-2004 rate is than
the historical background extinction rate.
b. Identify and describe one other mass extinction event that has occurred in Earth’s history.
c. Describe how speciation and extinction together determine the Earth’s biodiversity.
2. Temperate deciduous forests are rich and complex ecosystems.
a. Complete the diagram below of a temperate deciduous forest ecosystem by drawing arrows that show
the direction of energy flow.
b. Explain why it takes many hectares of forest to support a pair of owls.
c. The food web above does not contain detritivores or decomposers. Identify an example of a temperate
detritivore and a temperate decomposer that could be added to the food web.
d. Humans have a substantial impact on temperate forests.
i. Describe one specific human activity that degrades temperate deciduous forests.
ii. Describe TWO specific human activities that benefit temperate deciduous forests.
iii. Describe one U.S. federal law related to protection of forests.
e. Describe one difference between the soil of a temperate deciduous forest and the soil of a tropical
rainforest.
3. Read the following article from Marinebiotech.org and answer the questions that follow.
A casual look at a typical dock piling, seawall, ship hull, water intake pipe, or anything else manmade that's put into
the ocean environment gives you an appreciation for those industries that must contend with problems of marine
bioufouling.
Biofouling is generally defined as the settlement and accumulation of living organisms on man-made physical
structures placed in an aquatic or marine environment. The term usually refers to sessile (stationary) macroscopic
organisms like macroalgae, barnacles, bivalves, bryozans, sea squirts, and the like, but biofouling occurs very rapidly on
a microscopic scale as well. In fact, the formation of so-called microbial (bacterial) 'biofilms' is considered an essential
first step in the establishment of a marine fouling community.
The biofouling issue is more than aesthetic. The biological fouling of submerged materials is of great economic
importance to several industries, and is responsible for increased frictional resistance (drag) of fouled ship hulls;
structural deterioration (corrosion) of engineered materials; restricted flow through fouled aquaculture cage netting;
mechanical blockage of intake and outfall pipes; losses in heat-transfer efficiency of marine cooling systems; increased
costs for maintaining/replacing all of the above.
While it is difficult to put a figure on the worldwide cost of combating biofouling, the fact that the US Navy alone
spends about $1 billion every year on the problem hints at the economic scope involved. Fouling of a ship's hull can
decrease fuel efficiency by as much as 20-30%. This efficiency reduction represents a substantial financial liability since
fuel accounts for up to 50% of marine transportation costs. Additional costs come from hull cleaning, paint removal and
reapplication, and meeting environmental compliance standards. Not surprisingly, the Office of Naval Research (ONR)
allocates a considerable amount of money for research related to combating biofouling.
a. As described in the article above, biofouling is a marine version of succession. Is biofouling of a freshlypainted boat an example of primary succession or secondary succession? Explain your reasoning.
b. Identify the pioneer species described in this article and compare it to a pioneer species in terrestrial
succession.
c. Describe what a climax community would eventually look like on a dock piling or boat hull.
d. Biofouling represents a multi-billion dollar problem for marine industries. Based on the information in
the article, identify and describe one external cost associated with biofouling.
e. Zebra mussels are one species that may eventually attach themselves to a ship’s hull. Describe the
environmental impact of this attachment if a ship were to travel to a lake without Zebra mussels.
4. Two different classes were given Starbursts each day for a week. The initial population consisted of equal
frequencies of four flavors: 25% cherry, 25% strawberry, 25% orange and 25% lemon. Following each class, the
survivors of each day’s feasting (by students) reproduced, each spawning one offspring of the same color
(example: if there were 8 orange survivors at the end of class, then there would be 16 orange at the beginning of
the next class). Thus, color/flavor was passed from parent to offspring.
a. Describe ONE source of genetic variation in organisms for natural selection to act upon.
b. Which trait(s) were adaptive in 2nd hour? Which trait(s) were adaptive in 7th hour? Explain your reasoning.
c. The orange starbursts feed exclusively on the nectar of the endemic crunchberry flowers of the island chain
where they live.
i.
Describe the orange starburst’s niche.
ii.
Identify the species interaction that best describes the orange starburst/crunchberry flower
relationship.
iii.
The crunchberry bushes are being overharvested by Cap’n Crunch industries to the brink of their
extinction. Predict what will happen to the orange starbursts.
d. The starbursts in these two classes represented populations of a species on two different islands.
i.
Which type of speciation could be taking place? Explain.
ii.
Describe what would happen if the two populations were isolated for thousands of generations and
then brought back together. Explain the reasoning behind your answer.
e. This simulation is a model for natural selection in real organisms. Identify and describe ONE example of an
organism that has a NEGATIVE impact on humans that is being selected for in an analogous way to the
starburst simulation described here.