Decomposers are vital components of a food web because they:
answer
return carbon (as CO2) to the atmosphere.
question
Which of the following factors likely contributed to the accumulation of O2 within Earth's atmosphere?
answer
the fact that there is a slight "de-coupling" between photosynthesis and respiration
***All of these choices are correct.
the fact that oxygen is also cycled during the carbon cycle
the fact that photosynthesis releases O2 as a product
the evolution of cyanobacteria
question
Which of the following organisms can incorporate atmospheric carbon directly into C6H12O6, thereby playing a major role in a food web?
answer
primary producers
question
If all of the tertiary consumers were removed from an environment, the associated food web (and thus the carbon cycle) would collapse.
answer
False
question
Which of the following statements explains how an oxygen-rich atmosphere was possible?
answer
Rates of oxygen consumption were lower than rates of photosynthesis.
question
The evolution of biodiversity on the planet can be linked to patterns in the carbon cycle over time.
answer
True
question
The sequence of species that colonize a recently disturbed area through succession is unpredictable.
answer
False
question
Which of the following is a good predictor of biodiversity in terrestrial ecosystems?
answer
plant species in a community
question
In the example of the giant kelp forests on the Pacific coast, a rise in the otter population would have what effect on the kelp populations?
answer
Kelp populations would increase due to a decrease in sea urchins.
question
Keystone species can have significant influences over several populations in a community through their:
answer
effect on high amounts of biomass and energy transfer between populations.
question
While biodiversity includes the number of species in a given area, it also includes:
answer
unique phylogenetic lineages.
question
Following a disturbance, the process by which species replace each other over time is/are called:
answer
succession.
question
You decide to plant a garden in your backyard. You dig up a strip of grass in a sunny spot. When you have finished digging up the grass, but you haven't planted anything, you have created a(an) _____ in the lawn.
answer
ecological disturbance
question
The sum total of the populations that live in a given area is called a(n):
answer
community
question
A species that has a disproportionately large effect on a community is called a _____ species.
answer
keystone
question
Predator/prey relationships are always linear, with one species affecting only one other in the community.
answer
false
question
A _____ depicts the flow of carbon through an ecosystem, whereas a _____ depicts the transfer of energy.
answer
food web; trophic pyramid
question
Which group in a food web is responsible for returning inorganic compounds back to the environment?
answer
decomposers
question
While food chains show linear energy transfer between organisms, food webs depict more realistically what occurs in an ecosystem.
answer
True
question
Energy flow through ecosystems can be depicted using a(n):
answer
trophic pyramid.
question
The broadest level in a trophic pyramid is primarily composed of:
answer
primary producers.
question
Organisms that take up inorganic nutrients and convert them to organic molecules such as carbohydrates and proteins are called:
answer
primary producers.
question
A(n) _____ is a community of organisms and the physical environment it occupies.
answer
ecosystem
question
What is generally true about biomass and energy as we move from one trophic level to the next?
answer
Not all energy is transferred to the next trophic level.
question
Warm air is _____ dense than cold air, and warm air holds _____ moisture than cold air.
answer
less; more
question
How many "cells" of circulating air are found around the Earth?
answer
6
question
The high specific heat of water means that land masses near the equator are:
answer
cooler than predicted because of all the heat carried by ocean waters from low to high latitudes.
question
If Earth had no oceans, would temperatures at the equator be hotter or colder than they are now?
answer
Temperatures would be hotter.
question
The hypothesis that species diversity is greater at lower latitudes than higher latitudes because low-latitude habitats are older would be supported if speciation rates were:
answer
the same at high and low latitudes.
question
As you hike from the base of a mountain to the top of a mountain, you would expect see decreasing levels of biodiversity.
answer
True
question
Rainforests have high tree species richness, but low density. In deciduous forests the pattern is the opposite. Which of the following is NOT a plausible explanation for this pattern?
answer
There are fewer species in temperate regions because the number of trees per hectare is lower than in tropical rainforests.
question
What is the approximate size of the human population today?
answer
7 Billion
question
In general, what is the relationship between a country's ecological footprint and its overall standard of living?
answer
As the standard of living increases, so does the ecological footprint.
question
An individual's ecological footprint is equivalent to the:
answer
amount of land required to provide all the resources used by that individual.
question
A group of scientists in Alaska notices that not only have atmospheric CO2 levels increased at their sampling site but so too have methane levels. What most likely accounts for this increase in methane levels?
answer
The release of methane from thawed permafrost.
question
Which of the following statements is TRUE regarding the process of eutrophication?
answer
It can result in "dead zones" devoid of aquatic animal life.
question
Remember that, as a rule, temperatures decrease with an increase in altitude. If you were studying the effects of climate change on the geographic ranges of species living in the mountains and your climate records showed that mean temperatures were increasing, you would predict that species ranges would show a shift toward:
answer
higher elevations.
question
Which of the following statements about coral bleaching is TRUE?
answer
Bleached corals die more rapidly than unbleached corals.
Coral bleaching results from the loss of algal symbionts from the coral tissue.
***All of these choices are correct.
Corals appear white after bleaching because their white calcium carbonate skeletons are visible through their translucent tissue.
Increased seawater temperature is one cause of coral bleaching.
question
Most climate models predict that, during the 21st century, mean global temperature will increase by:
answer
2-5°C.
question
What is one "low-tech" method currently available to actively remove CO2 from the air?
answer
reforestation of previously cleared landscapes
question
Given models of population growth, which model would be the BEST to use for determining estimated sustainable yield?
answer
logistic
question
In addition to burning fossil fuels, humans return CO2 to the atmosphere faster than it can be removed by:
answer
clearing forests for agriculture.
question
Which of the following is an appropriate interpretation of the graph below?
answer
The anchovy catch grew through 1970, after which there was rapid decline without recovery.
question
Some biologists have suggested that overexploitation in the harvesting of some sharks (i.e. top predators) has caused drastic changes in marine communities. Which of the following would you expect after removal of a top predator from a community?
answer
population growth of prey species
question
Consider the figure below showing calculated sustainable yield for Peruvian anchovy. For years Peruvian anchovy were fished at their estimated sustainable yield. Which of the following is the BEST explanation for why the population crashed?
answer
The estimated sustainable yield was calculated at the maximum population size of Peruvian anchovy.
question
As a young field biologist, you are walking through a patch of grassland where you notice that there is a very common, well-established species of grass. Further research shows that this grass is native to an area in another part of the world. This species of grass would be classified as a(n) _____ species.
answer
invasive
question
If a scientist wanted to determine if a forest environment had been polluted, which of the following groups of organisms typically would be the BEST indicator for the presence of pollutants?
answer
amphibians
question
Some forms of M. tuberculosis are very difficult—or even impossible—to treat with antibiotics.
answer
True
question
Sustainable development plans are designed to allow:
answer
conservation of species used by humans without causing the decline or extinction of that species.
question
Increased overfishing on predators of crown-of-thorns starfish is likely to result in continued increase in crown-of-thorns starfish population sizes.
answer
True
question
Biologists who study biodiversity describe new species and monitor species of which we are aware. Why is the study of biodiversity important in the Anthropocene?
answer
The study of biodiversity is important because it helps quantify the effects of human actions on changes in the traits of many populations (size, density, distribution).
question
Genetic variation within species is important to conservation because:
answer
genetic variation provides material for natural selection to "act upon" in changing environments.
question
Biological reserves are an important tool in maintaining biodiversity because a reserve:
answer
that is designed for a single species will also protect other species in the reserve.
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