Bio Unit 8 MCQ
Which of the following best predicts the effects of an increase in killer whale predation on sea otters on the Adak Island ecosystem?
The sea urchin population will increase and the kelp population will decrease, leading to reduced total biomass and diversity in the Adak Island ecosystem.
How do the data in Figure 1 support the alternative hypothesis that increased use of Bt corn reduces the impact of corn farming on the natural environment?
The toxin in Bt corn kills only the corn pests, leaving other insects unharmed.
The marine iguana, Amblyrhynchus cristatus, is endemic to the Galápagos Islands and is especially vulnerable to El Niño events. These iguanas feed on red and green algae. During an El Niño climate event, surface waters and their currents in the central and eastern Pacific Ocean become significantly warmer than usual. Also during El Niño years, landmasses experience increased rainfall. A researcher suggests that El Niño conditions cause a significant decrease in the size of the Galápagos marine iguana population. Which of the following would best support this alternative hypothesis?
Warm surface water contains fewer nutrients needed by red and green algae than cooler surface waters does.
Which of the following is closest to the calculated wolf population size in 2017 based on the student's claim?
103
Based on information in Figure 1, which of the following is closest to the annual growth rate of the wolf population in Yellowstone National Park from 1996 to 2004 ?
17 wolves per year
The following equation is for trophic level transfer efficiency: (production at present trophic level/production at past trophic level) × 100 If primary producers produce 1,600 kcal/m2 and primary consumers have 800 kcal/m2, what is the trophic level transfer efficiency?
50
Pheromones are used in communication between some organisms. What is a pheromone?
A pheromone is a type of chemical compound.
Which statement best describes a pioneer species?
A pioneer species is a species that can colonize new landscapes and begin the process of succession.
The boreal forest, also known as taiga or coniferous forest, is found south of the Arctic Circle and across most of Canada, Alaska, Russia, and northern Europe. What is a characteristic of the boreal forest?
Acidic soil
Which statement explains the correlation between age structure and the level of economic development observed in many countries?
Age structures of economically undeveloped countries show greater proportions of children and fewer proportions of elderly people.
In which biome are plants unable to grow because the soil is frozen most of the year?
Arctic tundra
The amount of sunlight and rainfall affects the growing season of plants in different biomes. Which biome is characterized by short growing seasons?
Arctic tundra
Why do scientists more commonly analyze net primary productivity compared with gross primary productivity?
As respiration and heat loss uses energy of primary producers, net primary productivity is what is actually available to primary consumers.
What type of pyramid is considered the most representative of ecosystem structure?
Biomass
Corals have a mutualistic relationship with photosynthetic algae in the photic zones of water. What purpose does this serve?
Corals are able to derive their nutrition from the algae and thus survive in the nutritionally poor water.
In a microcosm experiment using fish tanks to mimic a lake environment, an increase in the number of stickleback species would increase the dissolved organic carbon particle size. How could this affect primary producers in the ecosystem?
Decrease abundance
Humans began developing oil as an energy source in the early part of the 20th century. Which statement describes the relationship between oil development and Earth's human carrying capacity?
Drilling for oil enabled humans to increase food production through the use of machinery, which increased Earth's human carrying capacity.
If a population moves to a new environment rich in resources, what type of growth curve will it exhibit in the short term?
Exponential
What type of growth curve do species with limited resources usually exhibit?
Logistic
What is the primary factor that limits the length of food chains in ecosystems?
Low energy transfer efficiency between trophic levels
Which example describes how an animal expends energy in finding, selecting, or winning a mate?
Male cardinals harass and peck at other male cardinals in their territory.
In a region in Texas, biologists observed that two highly venomous snakes with similar markings deter owl predators. Upon closer inspection, the snakes were determined to belong to different genera and species.How would these biologists describe the mimicry in this case?
Mu¨llerian mimicry because it involves different species that both produce toxins and display similar warning coloration
Which group of photosynthetic organisms is more likely to grow in a lake as opposed to a river?
Phytoplankton
An ecologist is planning to measure both the size and density of a population. Which experimental method can best provide these data?
Quadrat
What do the data in Figure 1 suggest about a null hypothesis that the East China Sea ecosystem is unaffected by climatic events?
The null hypothesis is rejected since there are significant effects of EAWM and PDO on surface sea temperature and copepod abundance.
Different varieties of potatoes are known to thrive at different altitudes. What could be the related benefit of maintaining the diversity of potato plants?
The range of usable land is extended.
Figure 1 shows the population fluctuations of phytoplankton and zooplankton in the eastern Pacific Ocean over the course of six years. The major dip in phytoplankton was attributed to a lack of nutrients for phytoplankton.
The reduction in the phytoplankton population meant that the zooplankton's energy source was drastically reduced, leading to the decrease in the zooplankton population size. After the dip, the phytoplankton provided a steady energy source, and the zooplankton population fluctuated around its carrying capacity.
Sea otters living along the Pacific coast were hunted to near extinction in the nineteenth century. After being protected from hunting in the early 1900s, a remnant population of otters near Adak Island, Alaska, recovered rapidly. Otters did not return to the environmentally similar nearby island, Alaid Island. Sea otters eat sea urchins, which eat kelp, a brown alga. Researchers surveyed both islands in 1988, to measure sea urchin biomass and kelp density. The data are presented in Table 1. Table 1. Kelp and sea urchin data from two Alaskan islands in 1988 In 1991, researchers at Adak Island observed the first attack by a killer whale on a sea otter in historical times. The researchers hypothesized that the population sizes of the larger marine mammals that the killer whales normally prey on declined, so the killer whales were starting to prey on different prey, including the smaller sea otters. Which of the following best predicts the effects of an increase in killer whale predation on sea otters on the Adak Island ecosystem?
The sea urchin population will increase and the kelp population will decrease, leading to reduced total biomass and diversity in the Adak Island ecosystem.
A researcher suggests that El Niño conditions cause a significant decrease in the size of the Galápagos marine iguana population. Which of the following would best support this alternative hypothesis?
Warm surface water contains fewer nutrients needed by red and green algae than cooler surface waters does.
Baker's yeast, Saccharomycetes cerevisiae, is the species of yeast that is commonly used in baking, brewing, and making wine. It is a single-celled organism; each cell is capable of undergoing asexual reproduction by mitosis and sexual reproduction by meiosis, forming spores that combine with other spores. To find out if energy and nutritional resource availability determines which form of reproduction is used, researchers grew twenty yeast colonies on an agar medium plate providing ideal nutrient environments. Each colony was composed of a population of yeast that originated from a single yeast cell that had reproduced asexually to form a population of millions of yeast clones. That plate was used to produce replicate plates of yeast colonies. Each replicate plate was a mirror image of the original cultures, so each colony could be subjected to each treatment group. The replicate plates contained different media as follows. Robust media: Contains all nutrients required by yeast in excess amounts Complete media: Contains all nutrients at a level promoting exponential growth at rmax Minimal media: Nutrients available at a low level, allowing growth, but stressing the yeast colonies Deficient media: Nutrient content less than what is needed to sustain growth, extreme stress on yeast colonies Eight replica plates were made, two plates of each media, and all plates were incubated at 30°C for 24 hours. Yeast from each colony were observed through a microscope and their means of reproduction determined. Table 1 summarizes these results. Table 1: Reproductive Strategy of S. cerevisiae under different environmental stress levels (20 different colonies per medium ×2)
Yeast respond to nutritional stress with sexual reproduction, producing new genetic combinations, or dormancy.
Which of the following best explains the data in Table 1 ?
Yeast respond to nutritional stress with sexual reproduction, producing new genetic combinations, or dormancy.
The study of the effect of abiotic factors such as rain and temperature on the distribution of living organisms is known as —
biogeography
Global temperatures have been steadily increasing since the Industrial Revolution largely as a result of —
burning fossil fuels
Populations with the greatest proportion of young individuals can be found in —
economically underdeveloped countries
Earth's geological past has witnessed many important events. Which period was associated with global warming?
Permian period
What are usually the primary producers in an ocean grazing food web?
Phytoplankton
Energy is a fundamental component in an ecosystem and is contributed by the primary producers. How can light energy, in turn, support the consumers of an ecosystem?
Primary producers convert light energy to chemical energy using photosynthesis and consumers gain energy by feeding on them or on other consumers that have consumed these producers.
If you wanted to measure gross primary productivity in a terrestrial ecosystem, what would you measure?
Rate of energy incorporation by plants
In the mid-1920s, gray wolves, Canis lupus, were eliminated from Yellowstone National Park in the northwestern United States. Over the course of 1995 and 1996, 31 wolves from Canada were relocated to the park. Researchers have tracked the growth of the wolf population from 21 in 1995 to 108 at the end of the study in 2016 (Figure 1).
Rest: Decreases Travel: No Effect Hunt: No Effect Feeding on Carcasses: Increases Vigilance: Increases
Which abiotic factor is most important for sustaining life in marine biomes?
Salt
Where are coral reefs found?
Shallow ocean water
What is a likely reason that small animals survived the cataclysmic impact of a large meteorite that caused the massive extinction at the Cretaceous-Paleocene?
Small animals needed less food for survival and reproduced rapidly.
Which of the following correctly identifies the dependent variable and the independent variable for the experiment?
The dependent variable is the percent change in the amount of nicotine, and the independent variable is the time interval the plants were exposed to the hornworms.
Why are mesocosm and microcosm experiments NOT considered to represent the true nature of ecosystems?
The ecosystem is either recreated or partitioned in both types of experiments, which may alter the dynamics of the ecosystem the experiments are aiming to analyze.
Backpackers returning from a long trip abroad are stopped by customs and asked whether they brought back plants, flowers, or fruit from their trip location. Their fruit bought at a local market is confiscated. What is the most likely reason why the fruit was confiscated?
The fruit may introduce new exotic pests that threaten local plants.
Climate change can affect oceanic ecosystems and their food webs. In the East China Sea (ECS) , three major climactic events were considered: the Pacific Decadal Oscillation (PDO) , the East Asia winter monsoon (EAWM) , and the El Niño Southern Oscillation. Figure 1 shows the relationships among these climactic events, surface sea temperature (SST) , amount of phytoplankton, and copepod abundance. Copepods are important primary consumers in this ecosystem, and many species of fish depend on copepods as a food source. Solid arrows on the diagram indicate a statistically significant effect. The thicker the arrow, the greater the effect. Dashed arrows indicate statistically insignificant relationships.
The null hypothesis is rejected since there are significant effects of EAWM and PDO on surface sea temperature and copepod abundance.
Bison in Yellowstone National Park have a food-limited carrying capacity that determines how their population grows. If the population grows too large, some bison will either starve or migrate to search for more food. The park is able to support a maximum population of 4,500 bison. Park conservation officials must watch the population and prevent the bison from overpopulating, since they would migrate to nearby farms, causing agricultural damage and creating hazards to drivers. The bison begin to migrate when the population reaches 4,000 because of competition for food. If the current population size of bison is 3,652 and the maximum growth rate of the population is 0.28, calculate the population size after one year and determine whether the park will need to take measures to control the population.
The population will be 3,845 after a year. The bison will not pose a problem until the following year, and no conservation action will need to take place.
Which of the following correctly identifies the dependent and independent variables in the described study?
The presence of pups is the independent variable, and the frequency of sentinel behavior is the dependent variable.
In the mid-1920s, gray wolves, Canis lupus, were eliminated from Yellowstone National Park in the northwestern United States. Over the course of 1995 and 1996, 31 wolves from Canada were relocated to the park. Researchers have tracked the growth of the wolf population from 21 in 1995 to 108 at the end of the study in 2016 (Figure 1).
The presence of wolves
Of the following, which explains why the zooplankton also dipped during the same year and then seemed to cycle over the next three years?
The reduction in the phytoplankton population meant that the zooplankton's energy source was drastically reduced, leading to the decrease in the zooplankton population size. After the dip, the phytoplankton provided a steady energy source, and the zooplankton population fluctuated around its carrying capacity.
What survivorship pattern can be used to describe humans?
Type I survivorship curve
Based on the data in Figure 1, which of the following statements is most accurate about the species diversity of the four different environments that the students analyzed?
Based on the data, there is no statistically significant difference between the species diversity of plants in the light, moist environment and in the dark, moist environment.
Which statement explains the symbiotic relationship of mutualism?
Both species benefit from the relationship.
Humans have altered their own carrying capacity. How have humans changed their carrying capacity, and what are the consequences of this change?
By increasing their own carrying capacity, humans have enabled their population to grow exponentially.
Many endemic species are found in areas that are geographically isolated. Which option is a plausible scientific explanation why this is so?
Geographically isolated areas have provided a unique environment for certain species to evolve. Over time, these species retain their unique characteristics because they remain separated from other species.
Ecologists often collaborate with other researchers interested in ecological questions. Which levels of ecology would most easily lend to collaborative research because of the similarities in the scope of questions asked?
It is easier to study community and ecosystem ecology as the effect of biotic and abiotic factors can be studied in a community or ecosystem more easily. Organismal and population ecology might be more difficult for collaboration.
What is community ecology? Give an example.
It is the study of the processes and consequences of interactions within and among different species within an area. An example would be the work of scientists who study the various interactions of several populations of birds, crabs, and grasses in a marsh without studying the water or air quality.
What would happen if the competitive exclusion principle were violated?
One species will contend with another species for the same resources.
In a study of energy flow, the following data were collected: Each human requires 55 grams of protein per day. An acre of soybeans produces 200,000 grams of protein per year. A cow grazing on one acre of land produces 19,000 grams of protein per year. Based on these data, an acre of land would support: 10 humans per year on a diet of soy, or 0.9 human per year on a diet of beef. Which of the following statements best explains these relationships in terms of energy transfer?
Only 10% of the energy on each level of the trophic pyramid is available for use by the next level. The rest is lost as heat or used for growth and repair.
Which of the following statements best explains these relationships in terms of energy transfer?
Only 10% of the energy on each level of the trophic pyramid is available for use by the next level. The rest is lost as heat or used for growth and repair.
In the mid-1920s, gray wolves, Canis lupus, were eliminated from Yellowstone National Park in the northwestern United States. Over the course of 1995 and 1996, 31 wolves from Canada were relocated to the park. Researchers have tracked the growth of the wolf population from 21 in 1995 to 108 at the end of the study in 2016 (Figure 1).
The reintroduction of wolves led to a decrease in the population of elk, allowing aspen trees to grow taller.
In grasslands, fires are a common occurrence. Which statement regarding grasslands is true?
They have a well-developed root system, which allows them to regrow after a fire.
In grasslands, fires are a common occurrence. Which statement regarding grasslandsis true?
They have a well-developed root system, which allows them to regrow after a fire.
An ecologist hiking up a mountain may notice different biomes along the way due to changes in all of the following except —
latitude
