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Which of the following contributes to the acidification of rainwater? burning of fossil fuels CO2 in the atmosphere SO2 (Sulphur dioxide) in the atmosphere all of the above the rising global temperature Biodiversity is a way for ecologists to quantify the community of an ecosystem. In general ecologists believe ecosystems are most stable and therefore healthy when biodiversity is high. If you needed to determine the diversity of tree species in a forest. How would you do this? a) collecting all the trees in the community b) determining the relative abundance of tree species present to one another c) counting every single organism present d) counting every single species present e) both A and D Omnivores: a) are always considered tertiary (3rd order) consumers b) consume only dead matter and waste products of other organisms. c) are never found in the first trophic level. d) may exist at any trophic level. e) feed only on primary producers. The beak sizes and shapes of Darwin’s finches, which are closely related to one another, are correlated with which environmental factor? a) relative height of nesting sites b) size of the island on which the birds are found c) total weight of seeds consumed during a day d) distance of the birds’ founding island from the mainland e) size of seeds eaten What drives the evolution of carnivory in plants? Think back to the greenhouse lab and plants such as the Venus Fly Trap. lack of nutrients lack of sunlight lack of water lack of competition all of the above The most effective nature preserves: focus on one species. consider ecosystem interactions. reduce buffer zones as much as possible. incorporate humans as much as possible. All of the above choices are correct. What abiotic factor limits primary productivity in typical deserts? water

sunlight average temperature only biotic factors limit primary productivity in deserts competition What abiotic factor usually limits primary production in aquatic ecosystems. water sunlight average temperature only biotic factors limit primary productivity in deserts nutrients (N + P) What is/are the underlying problem(s) causing algal blooms in the Great Lakes and Gulf of Mexico? Loss of natural wetlands along many of the rivers agricultural runoff increases the nutrients available to algae large watersheds have many rivers eventually draining into one area all of the above are correct B and C are correct

A population with a higher death rate than birth rate may still have positive growth. This statement is: a) incorrect; if death rate is higher than birth rate, the population will decrease. b) incorrect; birth rate must equal death rate for a population to have positive growth. c) correct; if emigration rate is higher than the death rate, the population will still have positive growth. d) incorrect; immigration and emigration play only a very small factor in population growth, the overall population growth is still determined by birth and death rates, thus a population with a higher death rate will have negative growth. e) correct; if immigration rates plus birth rates are greater than death rate plus emigration rate, population growth will still be positive even if birth rate is lower than death rate alone. Answer: e

On average, which leaves more offspring that survive to become adults and reproduce: a pair of elephants or a pair of rabbits? a) If both populations are stable, then the pair of elephants and the pair of rabbits will leave the same number of offspring that survive to become adults and reproduce. b) The pair of elephants will leave more, because any individual elephant born is more likely to survive to become an adult and reproduce. c) The pair of rabbits will leave more, because they have so many more offspring per breeding season than do the pair of elephants. d) The pair of elephants will leave more, because elephants live much longer and have more breeding seasons.

e) The pair of rabbits will leave more, because they reach sexual maturity more rapidly. Answer: a

Natural populations fluctuate in size through time. One force influencing population size is the physical environment, which can have both direct and indirect effects on population sizes. Changes in a population’s size due to environmental factors (aside from those that occur daily or seasonally) are likely to: a) be density-dependent. b) track the exponential growth model. c) track the logistical growth model. d) be predictable. e) be irregular, perhaps even random. Answer: e

When plants of a particular species are growing too close to each other, crowding may eventually lead to mortality, known as self-thinning. This type of mortality is: a) oscillating. b) density-independent. c) random. d) density-dependent. e) exponential. Answer: d

Populations that exhibit logistic growth still exhibit exponential growth. This statement is: a) true; populations exhibiting logistic growth go through a period of exponential growth before growth rates level off around zero. b) true; logistic growth is another term for exponential growth. c) false; populations exhibiting logistic growth show exponential growth when the population size is greater than the environment’s carrying capacity. d) false; exponential growth and logistic growth are characteristics of different species. e) true; however, this can only occur in different populations of the same organism because one population cannot exhibit both types of growth. Answer: a

The graph above represents the standard demographic transition—the pattern of population growth that is experienced as a country industrializes. In this graph, the green line represents __________________, the red line represents __________________, and the blue curve represents _________________. a) death rate; birth rate; population growth rate b) birth rate; death rate; total population size c) death rate; birth rate; total population size d) population growth rate; carrying capacity; total population size e) birth rate; death rate; population growth rate Answer: e How does exponential growth differ from logistic growth? a) Logistic growth generally comes with infinite expansion. b) Logistic growth models take the population’s age structure into account. c) Long-term exponential growth is more commonly observed than long-term logistic growth in nature. d) The logistic model of growth incorporates environmental limitations on population size. e) Exponential growth models include consideration of a population’s carrying capacity. Answer: d

In a population exhibiting logistic growth, what happens when the carrying capacity is exceeded? a) The population crashes and becomes extinct. b) The growth rate becomes negative until the population is back within the carrying capacity. c) The population’s fertility drops to zero. d) The growth rate becomes zero until the population is back within the carrying capacity. e) The population fluctuates around the new level. Answer: b

“Food chains are an accurate representation of energy flow through an ecosystem.” This statement is: a) false; the idea of producers, herbivores, and carnivores are human constructs. b) true; food chains accurately illustrate existing trophic levels. c) false; real ecosystems are much more complex than simplified food chains. d) true; however, they do not represent the amount of energy flowing through an ecosystem. e) false; food chains depict organism diets, not energy flow. Answer: c

When plants of a particular species are growing too close to each other, crowding may eventually lead to mortality, known as self-thinning. This type of mortality is: a) oscillating. b) density-independent. c) random. d) density-dependent. e) exponential.

Answer: D The majority of the world’s forests exist: a) in the northern hemisphere. b) in the southern hemisphere c) are evenly distributed between both hemispheres d) in Madagascar e) (it is unknown where most of the forests exist) Answer: A An umbrella species is a: popular species that the public tends to rally behind and support. non-native species, usually introduced to an area by accident. species whose removal will severely damage or cause the collapse of its ecosystem. species whose protection also results in the protection of many other species. Both the third and fourth choices are correct. Answer: D...