Environmental Exam 2
If a population has 250 births, 247 deaths, 12 immigrants, and 5 emigrants over 1 year, what is the population growth rate?
10 per year
Today's global extinction rate is ____________ times greater than Earth's background extinction rate.
100 to 1,000
Boulder reservoir contains 13,270 acre feet of water. 1 acre foot of water will support about 2.5 single family households per year and each family has an average of 4 people. If there were no more inputs of water to the reservoir and Boulder had to rely on this reservoir as the sole source of water, how many people could it support for one year?.
132700 people
In a system with three trophic levels starting with the input of 200 calories, roughly how many calories would be left by the top trophic level?
2
In this question, you will use a slightly different model of population growth that includes the limit of carrying capacity. Carrying capacity is the number of individuals than can live in a certain environment without diminishing the capacity of that place to support future populations. Imagine now a herd of wildebeests that has an initial population of 100 individuals, grows at a rate of 4%, and lives in a habitat that has a carrying capacity of 1,400 individuals. In approximately what year does the herd reach its carrying capacity?
200
Over what range of annual precipitation are forests found?
25-300cm
Using the same scenario (with a starting population of 100 wildebeests and 1% growth rate), determine approximately how many wildebeests are added to the population in the first 100 years. Then determine approximately how many wildebeests are added to the population in the second 100 years. About how many more wildebeests are added in the second 100-year period than are added in the first year?
300
The fossil record indicates the occurrence of how many mass extinction events?
5
Compare the population growth curves for the same wildebeest population (starting with 100 individuals) at growth rates of 1% and 2%. Approximately how many more wildebeests are in the herd in 200 years when it grows at a rate of 2% compared to rate of 1%?
5,000
IF there were 100 million species of Earth, how many species might we reasonably predict to become extinct annually assuming background extinction rates?
50 species
If a herd of wildebeests has an initial population size of 100 and grows at a constant growth rate of 1% approximately how many wildebeests would be in the herd in 200 years?
700
If the same herd of wildebeests (with an initial population of 100 individuals, living in a habitat with a carrying capacity of 1,400 individuals) grows at a rate of 8%, in approximately what year does the herd come within 100 individuals of its carrying capacity?
80
Which of the following best describes a population?
A group of organisms of the same species that live in a specific area in a given geological period.
Why is the following scenario wrong? A population of 100 grows by 3 in a year, resulting in an annual growth rate of 3% animals per year (for example, 106, 109, 112, 115, 118, and so on).
A growth rate of 3% will not add 3 animals per year to a population. It will add 3% of the existing population in the total
All of the following are examples of biological limiting factors that can constrain the growth of an organism except
A lack of sunlight
Despite the fact that in both of the previous comparisons the growth rate only changed by 1% (from 1% to 2%, or 4% to 5%), many more animals were added to the herd in the same amount of time (200 years) in the second comparison. Why does this occur?
A larger number of wildebeests are added in the first year at a 5% growth rate than a 2% growth rate (5 versus 2); this new, larger population then grows by an additional 5% (versus an additional 2%) in the following year. Thus, a 5% growth rate produces a significantly larger population in each subsequent year than a 2% growth rate
Which of the following best describes an endemic species?
A native species found in only one specific location
A prokaryotic cell lacks_______________.
A nucleus
Which of the following cases best describes a resilient community?
A population of exotic plants is all but diminished by deforestation; however, it rebounds quickly the following spring, and within a year the population returns to approximately its original numbers
Of the following populations, which one best demonstrates a high degree of ecological resistance after a hurricane along a coast?
A population of trees that was slightly damaged but had a very low overall mortality rate
WHich of the following best describes genetic drift?
A random change in the genetic makeup of a population
Water would flow most quickly through which if the following soils?
A soil consisting entirely of sand particles
Which of the following soils would generally be best for growing crops?
A soil consisting of equal amounts silt, sand, and clay particles
What is the best definition of a keystone species?
A species that has a disproportionately important role in the food web
If you had $1 million and could buy 1 square kilometer of land somewhere in the world in order to preserve species diversity, which of the following location would be the best investment (that is, would preserve the most species)?
A tropical rain forest
Examine the population growth curves for the same wildebeest population (starting with 100 individuals) at growth rates of 4% and 5%. Approximately how many more wildebeests are in the herd in 200 years when it grows at a rate of 5% compared to a rate of 4%?
About 1,300,000
Bases on the taxonomic groups shown here, approximately what percentage of the total threatened species in the United States and Canada are plants?
About 25%
What percentage of endemic species are also classified as threatened endemic species in Africa?
About 40-50%
What is the residence time of water in the atmosphere? The atmosphere contains about 10 km3 and about 430 km3 go into and out of the atmosphere each year.
About 8 days
Which of the following regions has the largest percentage of threatened endemic species?
Africa
What are the major types of physical limiting factors to life?
All of the above
Which of the following are characteristics of an organism that gives birth to a small number of offspring?
All of the above
Which of the following characteristics describes a type I survivorship curve?
All of the above
Which of the following invasions might cause important economic impacts?
All of the above
Which of the following resources could influence carrying capacity?
All of the above
All of the following are components of an ecosystem except
All of these are components of an ecosystem
Which areas of the world tend to have the greatest species richness?
Areas near the Equator
If you were instead focused upon reducing total rates of extinction by the greatest amount (that is, extinction of not just endemic species, but of all species), which region would you focus your efforts in?
Asia
Which region has the largest total number of threatened species based on the taxonomic groups shown here?
Asia
Domain Eukarya includes all the following except
Bacteria
Weathering involves the breakdown of
Bedrock
Which of the following scenarios best represents a mutualistic interaction?
Birds called oxpeckers land on zebras and eat parasites off their backs, providing food doe the oxpecker and pest protection for the zebra
Which of the following is not a major fertilizer nutrient?
Carbon (C)
Which of the following is not a plant macronutrient?
Carbon (C)
In past major extinction events, something happened (for example, climate change or meteorite impact), and then many species disappeared. What actually caused the species to disappear?
Conditions changed faster than the organisms were able to adapt to, and, as a result, these species eventually disappeared.
Which of the following accurately describes current trends in biodiversity and crop production?
Crop diversity has declined, as have populations of pollinators needed to pollinate our crops.
The process of mineralization is performed by
Decomposers
Which of the following examples is a good description of a community?
Different populations living close enough together to interact
Evolutionary speaking, which of the following groups of organisms appeared most recently?
Eukaryotes
In the scenario you just examined, the wildebeest population with an initial population of 100 is growing at a steady rate (1%), but about three times as many wildebeests are added to the herd in the second 100-year period as in the first 100-year period. What type of growth is occurring in this population and why?
Exponential. The population increases by more individuals each year when the population size is greater
Which of the following would be considered a regulating service?
Flood control
Which of the following is true about fluxes in the environment?
Fluxes are the transfer of molecules from one reservoir to another
If you were traveling to an unknown country but you knew that it received more than 125 cm of rainfall annually, what type of biome would you anticipate seeing?
Forest
Which of the following is NOT true about the history of forest management in the United States?
Forest management in the US hasn't changed at all in the past 200 years
Which of these statements best describes the distribution of forests, grasslands, and deserts and xeric shrublands, and when mean annual precipitation is from 25 to 50 cm per year?
Forests are found in the coolest regions, deserts and xeric shrublands are in the hottest regions, and most grasslands are in intermediate regions
Which of the following would you be considered a provisioning services?
Fuel wood
Migration of organisms contributes to which of the following causes of evolution?
Gene flow
Mass extinction events are characterized by the disappearance of 20% of the ___________ in the fossil record.
Genera
Read the following definition of niche utilization and choose the term that best describes this organism: lives in a forest, grassland, or human-dominated setting and feeds on a variety of different food types.
Generalist
Biodiversity is a measure of the diversity of life at what levels?
Genetic, species, and ecosystem
All of the following would result in secondary succession except
Global warming uncovering a boulder field in the arctic that has been covered with ice for thousands of years
Which ecosystem would you expect to have the more frequent fires (smallest fire interval)?
Grasslands
If you were interested in knowing whether an ecosystem was storing carbon from the atmosphere, which of the following equations would you want to use?
Gross primary productivity - (autotrophic respiration + heterotrophic respiration)
What's the primary (most important) cause of species extinction on Earth?
Habitat loss
Which of the following is the major cause of biodiversity loss on land?
Habitat loss
If a crop needs nitrogen, phosphorous, and calcium to grow, which of the following is true about that plant?
If nitrogen and phosphorous are available in large amounts and calcium is only available in small amounts, it is most likely to be calcium limited
Which of the following is an example of evolutionary change?
In a certain population of birds, the birds with larger beaks are better able to eat the hard seeds that are abundant in their environment. These birds survive and produce offspring with large beaks. Over time, the population has a larger proportion of birds with large beaks.
WHich of the following groups comprises the largest group of known species on the planet?
Insects and their kin
Which taxonomic groups appear most often as having the most threatened species across all regions?
Invertebrates and plants
The majority of the solar energy entering a forest ecosystem?
Is either reflected back to the atmosphere or directly converted to heat energy
How is it possible that we don't currently know how many species are present on Earth?
It is very difficult to measure insect and microbiological diversity accurately.
A small population of coyotes live in a desert habitat. There is plenty of habitat and prey available for these coyotes, but they typically do not have much water available to them, especially during the hot summer months. However, at one point in time, a series of very wet years occurs, which increases all the resources--including water--available to the coyotes. During this series of wet years, how is the coyote population likely to change?
It will grow exponentially
In 2001, a small population of mice in Colorado had 150 births, 110 deaths, 12 immigrants to the population, and 2 emigrants from the population. In 2002, Colorado experienced a severe drought. In this year, the birthrate for the population remained the same (150), but there were 140 deaths, 2 immigrants to the population, and 12 emigrants from the population. Keeping in mind the equation for growth rate (r=[B+I]-[D+E]), explain what the population curve would look like for this population during the period from 2001 to 2002.
It would show an increase in the population in 2001 and a flat line in 2002
Which of the following factors is most likely to be responsible for a population having a carrying capacity of 1,400?
Limited resources, such as food or space, and/or heavy competition for these resources
A density-forested area provides enough shelter and water for approximately 50 bears. If 30 bears move into this region and the population grows to 50, which of the following would be the best description of that growth pattern?
Logistic
In the previous simulation, you may have noticed that even before a population reaches carrying capacity, it grows much more slowly than it would under the conditions of unlimited, exponential growth. In other words, as the population reaches carrying capacity, the growth rate increasingly slows, unlike the first simulation in this activity, in which the growth rate remained the same over time. The graph shows the curves for both of these types of population growth. Which type of population growth is likely to occur more often in nature and why?
Logistic. Most populations face one or more factors that limit their growth over time.
Endemic species are species found in only one location. Regions with high numbers of endemic species are important for biodiversity conservation because you can maximize the number of species conserved per unit of habitat conserved. Based on the graph, which region has the largest total number of both total endemic species and threatened endemic species?
Mexico, Central America, and South America
Imagine you are leading a global species conservation organization and want to figure out how to prioritize your conservation efforts. One option is to focus on the regions that have the largest number of threatened endemic species. Based on this priority, in which two regions would you focus your conservation efforts?
Mexico, Central America, and South America; and Asia
Which of the following organisms would you most likely find on a Hawaiian lava field?
Microbes that need few nutrients
The species of what organisms are best characterized by genetic analysis?
Microorganisms
Many ecologist support the idea that more diverse ecosystems should be less affected by major environmental change than less diverse ecosystems. For example, a large drought would have a bigger negative impact on the life in a low-diversity ecosystem than it would on the life in a high-diversity ecosystem. Why would this be?
More diverse ecosystems have a broader mix of species, including some that are more likely to be able to tolerate changes such as drought, floods, or other extreme environmental events.
Which are the following statements about mutations and natural selection is true?
Most genetic mutations have little to no effect on an organisms.
Why is most of the world's water directly inaccessible to humans?
Most of the water on earth either is found in saline oceans or is stored in reservoirs like glaciers and permafrost that make it challenging to access.
Which of the following is NOT true about regional or national-scale water data?
Most regions of the world have the same per capita freshwater resources available
If you wanted to know whether or not an ecosystem was accumulating carbon from the atmosphere, which of the following would be the best measure?
NEP
Within an ecosystem, which of the following would represent the greatest amount of carbon dioxide?
Net ecosystem production (NEP)
What nutrient is typically most limiting in terrestrial environments?
Nitrogen (N)
Do natural disturbances harm ecosystems?
No, a disturbances is often essential to the long-term health and functioning of an ecosystem
Which of the following is not an organism "level" in the trophic structure?
Obtainers
Which of the following statements accurately describes how traits are passed to future generations?
Only traits that are a result of genetics can be passed down to the generation
Which of the following statements is true?
Organisms that are similar in appearance generally have genomes that are more similar than organisms that look quite different.
Which of the following is the major cause of biodiversity loss in Earth's oceans?
Overexploitation
Which of the following accurately describes the movement of oxygen in an ecosystem?
Oxygen is released into the atmosphere during photosynthesis
Which of the following is true about global water use?
Per capita water use has declined since the 1980s
Which of the following groups of organisms has the greatest percent of species at risk of extinction today?
Plants
Which of the following roles do plants plat in an intact ecosystem?
Plants provide energy to ecosystems in the form of sugars
Which of the following statements about evolution is true?
Populations evolve, but individual members of the population do not.
Some coral reefs are protected from being overrun with algae by a sea urchin that grazes on the algae. In one of these reefs, a disturbance even (such as a hurricane) severely damages the coral reef; however, enough sea urchins live in the system to keep the algal growth under control while the corals rebuild themselves. Which of the following terms best characterizes the ecosystem and why?
Resilient, because the ecosystem was able to return to it predisturbance state fairly quickly
Which of the following would be considered a cultural service?
Rock climbing
Fossils generally form in what kind of rock?
Sedimentary
Of the following examples, which one best represents a state change in an ecosystem?
Soil becomes increasingly sandy over many years of grazing
Which of the following would be considered a supporting service?
Soil formation
Which of the following is true about fires in the ecosystem?
Some plant species, like many pines, depend on fires to release seeds
Which of the following is an example of the use if biocontrol?
South American weevils are introduced to Lake Victoria to help eradicate the invasive water hyacinth
___________ is the process by which geographic isolation results in the formation of multiple species from a common ancestor.
Speciation
Which of the following is a good physical representation of a flux?
The Colorado River
Which of the following ecosystems is likely to have the largest carrying capacity (that is, can support the largest number of organisms)?
The Serengeti Plain, In southern Africa
Which of the following is true about carbon flows in an ecosystem
The carbon that a plant uses during photosynthesis cannot be lost or released in any way
What would you need to know to estimate when a fossilized fish lived?
The characteristics of the rock in which the fossil was found.
All of the following are major causes of biodiversity loss except
The collection of animals for zoos
Which of the following statements about ecosystem is true?
The concept of an ecosystem can applied to human-dominated landscapes
The background extinction rate is about 1 extinction per 1 million species per year. How does the current rate of extinction compare to the background extinction rate?
The current extinction rate is considerably higher (100 times or more) than the background rate
A herd of deer are introduced to an isolated island, where they survive by grazing on the grasses growing on the island. The island experiences a period of drought, during which the grasses that the deer are grazing on do not regrow at a normal rate, and soon the deer population has experienced the carrying capacity of the island. Assuming the drought continues, what is likely to happen to the ecosystem during this period?
The deer will continue to stay in the area until they all eventually die; by that point, the soil will have experienced significant as a a result of overgrazing, and the ecosystem is likely to be permanently changed.
An invasive plant is introduced to a small stream ecosystem that originally had a number of different plant species within it. The invasive plant uses a lot of water and soon outcompetes the other plants in the ecosystem. If this newly-changed ecosystem is faced with a major ecological disturbances, such as a pest infestation that affects a number of species, including the invasive trees, what is likely to happen?
The ecosystem will be less resilient (and likely degraded) because it is now less diverse due to the effects of the invasive species
While most major U.S. conservation policy focuses on species diversity, scientists also look at other levels of diversity, such as genetic diversity. Why would genetic diversity be an important factor to consider when investing the biodiversity of a group of organisms?
The genes of individuals within the same species can vary greatly, making some members of the same species more successful than others in certain situations.
Which of the following is NOT true about how soils are linked to hydrology?
The hydrologic cycle isn't impacted by soils
Marine sponges and microbes called cyanobacteria have a unique relationship. The sponge provides protection for the bacteria, and, in return, the bacteria provide nutrients for the sponge through the process of photosynthesis. Because both organisms benefit, their symbiotic interaction is mutualistic. However, if the environment suddenly changed to a point where the cyanobacteria did not access to light and thus could no longer photosynthesize, how would the symbiotic association change?
The interaction would likely become commensalistic because the cyanobacteria would continue to benefit from living on the sponge, but the sponge would not gain anything or be hurt by the bacteria (aside from the loss the nutrients that the sponges had been receiving)
This graph shows terrestrial (land) species richness in some of the majpr regions around the world. There are various hypotheses about why so many species are in the tropics, but on of them is that life in the tropical regions has been less affects by the major glacial cycles during which ice sheets cover the northern section of the planet. Why would this lead to higher biodiversity in these regions?
The lack of ice sheets means that there has been more uninterrupted time for speciation to occur, therefore leading to higher biodiversity
The northern-most area to which birds migrate is typically limited by the minimum nighttime temperature of the area. As the climate changes, the northern latitudes are likely to become warmer, allowing birds migrate further north. What process is this an example of?
The removal of an constraint on a group of organisms
Fill in the blanks: Intraspecific competition occurs when members of __________ species compete for _________________ resource(s)
The same; the same
Which part of soils are most important for plant growth?
The surface soil with minerals and organic material
Why does the Amazon rain forest generally have higher species diversity than temperate North American rain forests?
The temperature has been relatively stable over long periods of time in the tropics (where the Amazon rain forest is located) in comparison to other areas of the world.
Which of the following is true about fire management at the wildland-urban interface?
There is often a lot of fuel from vegetation and houses which can cause fire to spread quickly
What major impacts did photosynthetic bacteria have on Earth's atmosphere?
They begun to produce oxygen, which accumulated in the atmosphere.
Which of the following statements about biodiversity is true?
They use of only a handful of species for the vast majority of our crops has made our food supply more vulnerable to pests and disease.
A small mouse population found in the Front Range of Colorado looks and acts very much like most other mice in the area; yet, this particular group of mice is thought by many to deserve protection under the U.S. Endangered Species Act (ESA). How could this be?
This particular group of mice appears to be genetically distinct (sub)species and therefore would qualify for protection under the ESA
Which of the following statements regarding the benefits of biodiversity is true?
Traditional cost and benefit analyses of economic activity largely ignore the benefits of ecosystems and biodiversity, and therefore global ecosystems and biodiversity are in serious peril
Explain what is wrong with the following statement: Giraffes have developed long necks over many generations because they keep stretching higher and higher to reach the highest leaves on trees.
Traits, such as long necks, are developed over many generations through the process of natural selection; they are the result of a lifetime of activity.
The cones of some coniferous trees are serotinous, which means they need heat in order to open. When forests of these experience a fire, the cones become reproductively viable (that is, they are able to reproduce and grow into new trees). When coupled with the extra sunlight available to the new plants after the understory of the forest had burned, these plants can thrive. Which of the following processes is this an example of?
Trees exploiting resources after competition is removed
Which of the following is something that humans can do to minimize the impacts of fire on human populations?
Use management to reduce available fuel in forests so when fires occur they aren't as severe
A species classified as _____________ by the ICUN is likely to become endangered unless threats to its existence are reduced.
Vulerable
The Colorado River is an important source of water to Southern California. What would happen to water supplies to California if there were no dams and reservoirs on the Colorado river?
Water supplies would become much more variable and unpredictable
Which of the following is an example of a NON-consumptive water use?
Water used when flushing a toilet
Which of the following would stress an organism that lives in a warm desert environment?
Weather that is much hotter or colder than usual
What are the major differences between a population that is experiencing logistic growth and one that is experiencing exponential growth?
When a population experiences logistic growth, it will eventually level off as it reaches carrying capacity; when a population experiences exponential growth, it will increase at a steady rate indefinitely
What differences a non-native species from an invasive species?
When a species has been introduced to a new place but causes little damage, it is called non-native; when the non-native species begins to outcompete native species and cause ecological or economic impacts, it is deemed invasive
Why is a mutation an important aspect of how evolution occurs?
Without mutations in genes, there would be no variation in traits that could be selected for
There are many different definitions of a species. These include the capacity to interbreed, physical similarities, genetic similarities and others. Biologists spend a fairly large amount of time worrying about this definition, but does it make any difference for biodiversity conservation policy?
Yes, because laws such as those in the U.S. Endangered Species Act focus on species-level conservation of threatened or endangered species.
Which of the following is the best example of an ecosystem?
Your intestinal tract and all of the microbes
A biodiversity hotspot is
a threatened habitat that has high levels of species diversity and a large number of endemic species
What is the largest consumptive use of freshwater globally?
agriculture
A gene is a sequence of compounds found within what kind of molecule?
deoxyribonucleic acid
If two species are members of the same class, they would also have to be members of the same___________.
kingdom
