DNA Function Gene Expression micoevolution Macroevolution evolution UNIT 8,9,10 Quiz

DNA Function Quiz

Schedule:

After deadline.Ended 02/14/2019 11:59 PM EST

Started:02/08/2019 12:53 PM EST

Submitted:02/08/2019 1:05 PM EST

Score:90%

Points:90 out of 100

Question 1

Points: 10 out of 10

During DNA replication, it is possible for the T residue in the template strand to form two hydrogen bonds with a T base on the new strand. This doesn’t normally occur because:

•  The normal A-T base pairing uses 3 hydrogen bonds, so it will be preferred.
•  The T-T basepair contains two of the smaller sized bases.
•  The two T-T hydrogen bonds will be weaker than the two hydrogen bonds between an A-T pair.
•  DNA polymerase cannot incorporate T into the newly synthesized strands.

Feedback

Correct, a small base is paired with a large base.

Question 2

Points: 0 out of 10

Does the DNA in the skin cell have the same sequence of bases as the DNA in the brain cell of the same organism?

•  Yes, the sequence of bases should be the same in all cells of an organism.
•  No, the DNA sequence will vary based on cell type.
•  No, some cells will have mom’s DNA, other cells will have dad’s DNA.
•  Yes, the sequence of ALL DNA is the same.

Feedback

Incorrect, cells in the human body have DNA from both parents! (red blood cells are the exception: they lose nucleus with its DNA when they mature)

Question 3

Points: 10 out of 10

If radioactive nucleotide bases were provided to bacteria during DNA synthesis, then after cell division you would find:

•  Neither would be radioactive because DNA polymerase can distinguish between isotopes.
•  Both bacteria would be equally radioactive.
•  One bacteria would be radioactive and the other not.

Feedback

Correct, during DNA synthesis the newly synthesized strand will be radioactive while the template will be the original, non-radioactive, DNA. Each bacteria well get one copy of the new, radioactive DNA.

Question 4

Points: 10 out of 10

What is the end result of DNA replication?

•  Two DNA molecules each both have two new strands.
•  Two DNA molecules which each have two new strands and two old strands.
•  Two DNA molecules which each have one old strand and one new strand.
•  Two DNA molecules one with two old strands and one with two new strands.

Feedback

Correct. Each new DNA strand is made from one of the two old strands. This new strand and its template are the new DNA molecule.

Question 5

Points: 10 out of 10

PCR differs from DNA replication in which of the following ways?

•  Primers are needed.
•  A polymerase is needed.
•  A single copy of DNA is made.
•  Double stranded DNA is the product.

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Correct, DNA replication produces one copy, but PCR produces many copies of DNA.

Question 6

Points: 10 out of 10

Skin cells perform very different functions compared to brain cells. On the molecular level, what makes skin cells different from brain cells in the same organism?

•  Proteins
•  ATP
•  DNA
•  pH

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Correct

Question 7

Points: 10 out of 10

A typical PCR cycle consists of steps at different temperatures, typically 55, 78 and 98 oC. The correct order of these steps is?

•  98, 55, 78
•  78, 98, 55
•  78, 55, 98
•  98, 78, 55
•  55, 98, 78
•  55, 78, 98

Feedback

Correct. First you denature the DNA at 98o C and then let the primers anneal at 55o.

Question 8

Points: 10 out of 10

Which part of the nucleotide stores the genetic information?

•  Deoxyribose
•  Phosphate group
•  Nitrogen base
•  Ribose

Feedback

Correct. The specific sequence of nitrogenous bases used by DNA is how information is stored in the DNA.

Question 9

Gene Expression Quiz

Schedule:

After deadline.Ended 02/14/2016 11:59 PM EST

Started:02/08/2016 1:06 PM EST

Submitted:02/09/2016 9:52 AM EST

Score:100%

Points:100 out of 100

Question 1

Points: 10 out of 10

A gene codes for a protein that is 500 amino acids long. Which of the following mutations is likely to be the most deleterious?

•  a nonsense mutation at the fifth codon
•  a nonsense mutation at the 490th codon
•  a missense mutation at the 490th codon
•  a missense mutation at the fifth codon

Feedback

Correct. This would produce a polypeptide that is only four amino acids long. This would certainly not have the same function as the original protein.

Question 2

Points: 10 out of 10

Which of the following mutations would not be noticeable when studying the expressed traits (or proteins) of an organism?

•  missense
•  frameshift
•  silent
•  nonsense

Feedback

Correct. Silent mutations result in identical proteins and are only visible when studying DNA.

Question 3

Points: 10 out of 10

Identify the flow of genetic information during protein synthesis in a eukaryotic Cell.

•  mRNA moves a protein to the DNA and makes a copy of the DNA through translation.
•  Transcription produces an mRNA molecule in the nucleus. The mRNA moves to the cytoplasm where translation occurs.
•  DNA makes a copy of itself which is transported from the nucleus to the cytoplasm by a chain of amino acids.
•  Translation produces a tRNA molecule in the nucleus; the tRNA transports a protein to the cytoplasm of the cell.

Feedback

Correct. Transcription produces RNA in the nucleus, and translation produces proteins in the cytoplasm.

Question 4

Points: 10 out of 10

Which of the following statements is correct regarding DNA replication, PCR, and transcription?

•  Both DNA replication and PCR use DNA polymerases.
•  All three processes require primers.
•  All three processes happen in the cell naturally.
•  All three processes result in a double stranded product.

Feedback

Correct. In both processes, double stranded DNA is produced with the help of DNA polymerases.

Question 5

Points: 10 out of 10

Which of the RNA molecules can best be described as a copy of the gene that codes for a protein? (This RNA molecule carries the genetic information necessary to build a protein)

•  mRNA
•  tRNA
•  rRNA
•  all of these

Feedback

Correct, mRNA is a copy of the gene and carries the genetic information necessary to build the protein.

Question 6

Points: 10 out of 10

Transcription produces:

•  RNA from a DNA template
•  Proteins from a DNA template
•  DNA from a DNA template
•  Proteins from an RNA template

Feedback

Correct. Transcription produces RNA using a DNA template.

Question 7

Points: 10 out of 10

Which nitrogen base is not found on nucleotides used to build the new molecule in transcription?

Feedback

Correct. RNA does not contain this nitrogen base.

Question 8

Points: 10 out of 10

The tRNA with UAU as the anticodon would be attached to which amino acid?

•  isoleucine
•  tryrosine
•  serine
•  leucine

Feedback

Correct. If the tRNA has UAU as the anticodon, the mRNA must have had AUA as the codon. AUA codes for isoleucine.

Question 9

Points: 10 out of 10

When a cell is getting ready to divide into two cells (during the process of mitosis), which process must first happen so that the entire genome can be passed to the new daughter cells?

•  PCR
•  transcription
•  DNA replication
•  translation

Feedback

Correct. DNA replication produces a new double helix. Each of these DNA molecules can then be passed on to the daughter cells.

Question 10

Points: 10 out of 10

A gene codes for a protein that is 500 amino acids long. A nonsense mutation occurs at the 6th codon. What is the result?

•  A polypeptide that has a different amino acid at position 6.
•  A polypeptide that has the correct amino acids for the first 5 position, and then incorrect amino acids after that.
•  A polypeptide that is 5 amino acids long.
•  A polypeptide that is missing the 6th amino acid.

Feedback

Correct. A nonsense mutation leads to a premature stop codon.

Introduction to Evolution Quiz

Schedule:

After deadline.Ended 02/21/2016 11:59 PM EST

Started:02/17/2016 9:45 AM EST

Submitted:02/17/2016 9:58 AM EST

Score:100%

Points:60 out of 60

Question 1

Points: 10 out of 10

How does evolution occur?

•  The genetic makeup of a population changes over generations of time.
•  All of these are true.
•  The genetic makeup of an individual changes in response to the environment.
•  The genetic makeup of a population changes seasonally.

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Correct. The evolution of a population occurs over generations.

Question 2

Points: 10 out of 10

Below are some examples of changes that occur in life. Which one is an example of biological evolution?

•  Your taste in music changes dramatically between middle school and high school.
•  A young man’s muscles increase in strength and bulk after he starts lifting weights.
•  In New York City, the average wing length of pigeons decreases over a period of 150 years.
•  A cell starts to express a different set of genes when it is exposed to high levels of testosterone.

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Correct. This is a change in a population over many generations of time and is an example of biological evolution.

Question 3

Points: 10 out of 10

Which is not a component of the modern theory of biological evolution?

•  All life forms are related by ancestry from one or a few single-celled common ancestors.
•  Natural selection explains life’s adaptive features.
•  Changes in the genetic makeup of a population can occur over time.
•  Individuals gain experience during the developmental process that lead to evolution of the thought process.

Feedback

Correct. Changes in individuals over a lifespan do not qualify as biological evolution.

Question 4

Points: 10 out of 10

Which of the following ideas would fit within the theory of evolution as proposed by Charles Darwin and as accepted today?

More than one option is correct; select only those options that qualify as modern scientific views of evolution.

•  Fossils are traces or remains of organisms that existed in the past and reveal the history of life on Earth.
•  The Earth is no more than 10,000 years old.
•  The present is the key to the past; over time, the Earth has changed under the influence of slow natural processes that continue to operate today.
•  All living species are related by descent from one or a few common ancestors.
•  Species do not change or go extinct; each species is so complex and perfect that it must have been designed by an intelligent being.

Feedback

Correct. It is abundantly clear that fossils reveal the history of life on Earth given the many thousands that have been described and analyzed. The idea that the ‘present is key to the past’ is the general assumption of geologists, evolutionary biologists, and others who attempt to reconstruct past events based on analysis of “crime scene” evidence like fossils or DNA sequences. Finally, the theory that all living species descended from a few common ancestors is supported by many detailed similarities that unite living organisms.

Question 5

Points: 10 out of 10

Natural selection results in…

•  Increase in adaptive traits over time
•  Mutations in the genetic makeup of a population
•  All of these
•  Environment stresses on a population

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Correct. Natural selection allows better adapted organisms to survive and reproduce more successfully.

Question 6

Points: 10 out of 10

Which statement is true about Charles Darwin?

•  He was the first to ask questions about the origins of life.
•  He was the first to publish the traditional belief of evolution.
•  He was the first to propose a hypothesis for the origin of life.
•  He was the first to outline the modern theory of evolution.

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Correct. Darwin demonstrated evidence for and outlined a coherent theory of the evolutionary process.

Microevolution Quiz

Schedule:

After deadline.Ended 02/21/2016 11:59 PM EST

Started:02/17/2016 9:59 AM EST

Submitted:02/17/2016 10:06 AM EST

Score:100%

Points:90 out of 90

Question 1

Points: 10 out of 10

Which gene pool has changed through some process of microevolution?

•  Your cells express different genes today than they did when you were born.
•  A moth population increases from 3,000 individuals to 33,000 individuals over a period of favorable weather.
•  A mouse population (about 10,000 mice total) starts with 99% of the mice tan and 1% white; after 20 years 70% are tan and 30% are white.

Feedback

Correct. White fur color is very likely an inherited characteristic caused by a genetic variation (allele) whose frequency has increased in the gene pool over time.

Question 2

Points: 10 out of 10

______________ can occur only if there are two or more separate gene pools that are exchanging individuals (through migration) or genes.

•  gene flow
•  natural selection
•  genetic drift
•  mutation

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Correct. Gene flow occurs when two or more populations mix.

Question 3

Points: 10 out of 10

The sickle cell allele is more likely to have higher prevalence in populations where:

•  Antibiotics are not available
•  Malaria is present
•  Malaria is not present
•  Antibiotics are available

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Correct. The heterozygous condition for this allele confers an advantage in areas where malaria is common.

Question 4

Points: 10 out of 10

Humans are the only primate species in which mammary glands (breasts) remain large and prominent throughout adulthood. Other primates’ mammary glands swell only when they are nursing offspring; scientists are not sure why human females have noticeable breasts on a permanent basis. One hypothesis is that they increase a female’s ability to attract mates. If so, this would be an example of a trait favored by…

•  natural selection
•  sexual selection
•  artificial selection
•  genetic drift
•  gene flow

Feedback

Correct. If the main function of the prominent breast is to increase mating success, this would be an example of sexual selection.

Question 5

Points: 10 out of 10

What sorts of effects do new mutations have on the individuals that inherit them?

•  Mutations disrupt the normal development of an organism. They produce phenotypes that are bizarre and have a poor chance of survival.
•  Mutations do not affect proteins or alter phenotypes; they only affect gene sequences (DNA).
•  Mutations can have a wide range of effects on proteins and therefore phenotypes. They may have no effect, a negative effect, or a positive effect on survival, growth, mating success, etc.

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Correct. Mutations have a wide range of effects and are a normal feature of biology.

Question 6

Points: 10 out of 10

A population of pond snails has two genetically determined types: one with a black stripe on its shell and one with a plain brown shell. Evidence indicates that there is absolutely no difference between the two snail types in terms of their fitness: each type survives, grows, and mates with the same average level of success. Over time, black-striped snails become more or less common in a population due to chance events. At one point, for example, the pond nearly dries up and the few surviving snails happen to be mostly black-striped. This evolutionary change is the result of…

•  genetic drift
•  sexual selection
•  mutation
•  natural selection
•  gene flow

Feedback

Correct. Genetic drift occurs when allele frequencies change due to random events. It often occurs when populations are brought to low sizes by catastrophes (bottleneck effect).

Question 7

Points: 10 out of 10

A storm uproots 60% of the trees in a population. This is an example of:

•  Genetic drift
•  Gene flow
•  Natural selection
•  Gene pool

Feedback

Correct. Genetic drift refers to random events that change the frequency of alleles and genotypes in a population.

Question 8

Points: 10 out of 10

Each year a gardener saves seeds from those tomato plants that produce the juiciest fruits. She uses these seeds to plant the next year’s crop of 20 plants. Over time, the gardener develops her own special variety of very juicy tomatoes. This is best described as an example of…

•  sexual selection
•  natural selection
•  genetic drift
•  mutation
•  artificial selection

Feedback

Correct. The tomatoes that were most successful were favored because of the preferences of a human breeder.

Question 9

Points: 10 out of 10

Modern HIV therapy controls HIV infection through what strategy?

•  A single drug that stops viral replication is paired with another drug that prevents the virus from mutating so that it cannot evolve resistance.
•  Several different drugs are used that target different viral enzymes; if the virus evolves resistance to one drug, a different set of drugs is used.
•  A single very effective drug stops viral replication by targeting a key viral enzyme that is indispensable to the virus.

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Correct. This is HAART (Highly Active Anti-Retroviral Therapy) and has been very successful in controlling HIV infections.

Macroevolution Quiz

Schedule:

After deadline.Ended 02/21/2016 11:59 PM EST

Started:02/17/2016 10:06 AM EST

Submitted:02/17/2016 10:17 AM EST

Score:100%

Points:100 out of 100

Question 1

Points: 10 out of 10

According to the data presented here, modern birds are most closely related to

•  Deinonychosauria
•  Pterosauria
•  Ancient birds
•  Tyrannosauroidea

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Correct. This is the closest group to modern birds.

Question 2

Points: 10 out of 10

We can see evidence for the relatedness of humans, wheat plants, and bacteria if we compare their…

•  ribosomes
•  embryonic development patterns
•  body structures
•  muscle cells

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Correct. This is an intricate structure that is found in every living cell. Similarities indicate relatedness at the broadest level; all life forms a single clade.

Question 3

Points: 10 out of 10

Which best sums up the relationship between microevolution and macroevolution?

•  Microevolution and macroevolution are separate processes that operate under different principles and are not linked.
•  Microevolution occurs through or as a result of macroevolution; it is the outcome of macroevolution operating over long time scales at high levels of organization.
•  Macroevolution occurs through or as a result of microevolution; it is the outcome of microevolution operating over long times scales at high levels of organization.

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Correct. Macroevolutionary changes result from microevolution operating over long periods of time and within biological lineages instead of individual gene pools.

Question 4

Points: 10 out of 10

How might phylogenetics help scientists fight a new flu outbreak?

•  Scientists could compare the genetics of the viruses and trace the source of the outbreak.
•  Scientists could compare the symptoms of the new virus with genetically related viruses.
•  All of these
•  Scientists could compare the genetics of the virus to determine useful antivirals.

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Correct. All of these are true.

Question 5

Points: 10 out of 10

Which form of speciation occurs while the organisms are living in the same geographic area?

•  Sympatric speciation
•  Parapatric speciation
•  Allopatric speciation
•  Peripatric speciation

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Correct. Sympatric speciation occurs without physical separation.

Question 6

Points: 10 out of 10

The formation of new biological lineages is called _____________.

•  mutation
•  genetic drift
•  speciation
•  natural selection
•  sexual selection

Feedback

Correct. Speciation is the formation of a new species, or biological lineage.

Question 7

Points: 10 out of 10

A rare (fictitious) plant species, the Frilly Philodendron, contains a chemical that is helpful in controlling cancer. Biologists would like to find similar chemical compounds and test them for potential medical use. Which would be the most efficient strategy for finding these chemicals?

•  Do a phylogenetic analysis and then look in plants that are closely related to the Frilly Philodendron. They will probably produce similar chemical compounds.
•  Base your search on geography. Look in other plants that live in the same region as the Frilly Philodendron. They should have similar chemistry because they are exposed to similar climate.
•  Base your search on ecology. Look in other plants that live in the same specific habitat with the Frilly Philodendron. In particular, examine all the plants that grow in the same soil type, because they will probably have similar chemistry.

Feedback

Correct. Chemicals produced by a plant are encoded in their genes, so close relatives are most likely to make similar chemicals.

Question 8

Points: 10 out of 10

Which of the following is true?

•  Microevolution and macroevolution are not related.
•  Microevolution can lead to macroevolution.
•  Microevolution and macroevolution are the same thing.
•  Macroevolution can lead to microevolution.

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Correct. Macroevolution occurs through the process of microevolution.

Question 9

Points: 10 out of 10

According to the phylogenetic tree diagram above, Old world monkeys are most closely related to:

•  New world monkeys
•  Lemurs and Lorises
•  Tarsiers
•  Apes (including humans)

Feedback

Correct. Apes, humans, and old world monkeys share a common ancestor that is more recent than that between old world monkeys and the other primate groups.

Question 10

Points: 10 out of 10

Which of the following terms would contain all of the other terms within it i.e. which is the most inclusive.

•  Species
•  Clade
•  Individual
•  Population

Feedback

Correct. Clades contain groups of related species, species are made up of different populations, and populations are made up of individuals. Therefore, clade is the most inclusive term in this list.

Populations Quiz

Schedule:

After deadline.Ended 02/28/2016 11:59 PM EST

Started:02/17/2016 10:17 AM EST

Submitted:02/22/2016 9:07 AM EST

Score:70%

Points:70 out of 100

Question 1

Points: 10 out of 10

When does a self-limiting population such as a population of large fish or mammals grow the fastest?

•  When it is large and close to carrying capacity.
•  When it is low, about 10% of carrying capacity.
•  When it is moderate in size, about half of carrying capacity.

Feedback

Correct. At this level there are many breeding individuals but the effects of crowding are minimal.

Question 2

Points: 0 out of 10

Montana Vital Statistics 2010 Report

Source: Montana Department of Public Health and Human Services, Vital Statistics 2010 Report and US Census Bureau Montana QuickFacts.

Variable

Value in 2010

N (human population size)

989,415

Annual number of births

12,058

Annual number of deaths

8,803

Total land area

376,962 km 2

What was the per capita rate of change in Montana’s population in 2010?

•  -0.001
•  0.001
•  0.9
•  1.1
•  0.003

Feedback

Incorrect. The per capita rate of change = per capita rate of birth − per capita rate of death; not per capita rate of death / per capita rate of birth with intermediate results rounded prematurely.

Question 3

Points: 10 out of 10

A population is

•  All the species in a given area at one point in time.
•  All of the living organisms in an area plus the nonliving factors that interact with them.
•  All the individuals of a particular species within a given area at one point in time
•  All the species in a given area that actively interact with each other.

Feedback

Correct. A population is all the individuals of a given species in a given area at a given time

Question 4

Points: 10 out of 10

Montana Vital Statistics 2010 Report

Source: Montana Department of Public Health and Human Services, Vital Statistics 2010 Report and US Census Bureau Montana QuickFacts.

Variable

Value in 2010

N (human population size)

989,415

Annual number of births

12,058

Annual number of deaths

8,803

Total land area

376,962 km 2

What was Montana’s per capita birth rate for 2010?

•  0.03
•  0.01
•  82
•  12,060

Feedback

Correct. Per capita birth rate = births / N

Question 5

Points: 10 out of 10

Which graph below depicts an exponential growth pattern?

Feedback

Correct

Question 6

Points: 0 out of 10

Aphids are tiny plant-sucking insects that complete a life cycle in a few weeks. A population of aphids is likely to be…

•  unlimited; able to increase exponentially without any kind of limitation.
•  self-limiting; limited by factors that become stronger as the population is more crowded.
•  limited by unpredictable outside factors such as weather.

Feedback

Incorrect. No population can increase exponentially forever.

Question 7

Points: 10 out of 10

Most pest populations can be easily and effectively managed by occasionally killing most of the individuals, for example by using a chemical weed or insect killer.

Feedback

Correct. With their high birth rates, these populations are often hard to control using a single method. It may be necessary to limit birth rates as well, for example by reducing the available egg-laying habitat.

Communities Quiz

Schedule:

After deadline.Ended 02/28/2016 11:59 PM EST

Started:02/22/2016 9:09 AM EST

Submitted:02/22/2016 9:42 AM EST

Score:80%

Points:80 out of 100

Question 1

Points: 10 out of 10

A sample of insects and other invertebrates is collected from an urban stream. A total of 244 individuals is collected from 2 m2 of stream bottom habitat. In this sample there are 22 recognizably different types of invertebrate. The average total length of the individuals is 6.7 mm. What is the best estimate of species richness based on these data?

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Correct. If each recognizable type is a species, the estimated species richness based on this sample is 22 species in the community.

Question 2

Points: 10 out of 10

Which of the following are examples of symbiosis? Select all that apply.

•  Head lice complete an entire life cycle within a person’s hair and scalp; they cannot survive long away from a human host.
•  Deer range widely feeding on many different types of grasses, herbs, and woody plants.
•  Bees feed on flower nectar and pollen; in the process they move pollen from one flower to the next and help plants mate.
•  Archaea (prokaryotes) live in the guts of ruminants like cattle; they help cattle digest plant fibers and in return are provided with a warm place to live and abundant food.
•  Bark beetles live, feed, and breed within the soft wood just beneath the bark of their host trees. They leave the tree only for a brief time as adults.

Feedback

Correct. Two species live in close contact in these example.

Question 3

Points: 10 out of 10

Occasionally American alligators are sighted in rivers or lakes in New York City, far north of their usual range. These alligators are usually escaped pets. There is no self-sustaining population of alligators in New York, and they have no important influence on other populations there. Is the American alligator a member of the ecological community in New York?

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Correct. The alligator does not have a self-sustaining population in New York and does not affect other species populations there.

Question 4

Points: 10 out of 10

By damming streams, American beavers produce swamp, open marsh, and pond habitats that would not otherwise exist. Ecologists have compared the species diversity in regions with and without beaver populations. If the beaver is a keystone species, what do you think they found?

•  Beaver did not influence the diversity of other species.
•  Species diversity was higher in areas with beaver.
•  Species diversity was higher in areas without beaver.

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Correct. Keystone species support higher species diversity by maintaining or supporting community types that would otherwise collapse.

Question 5

Points: 10 out of 10

Two species with very similar resource requirements that live in the same area are most likely to interact in what way?

•  mutualism
•  competition
•  predation

Feedback

Correct. Similar species are likely to compete.

Question 6

Points: 10 out of 10

In Africa, grasses are the main vegetation in savanna communities. Acacias and other trees are few and widely scattered. Elephants range over very large territories and are not very abundant in any one location. However, they strongly affect the community by uprooting and consuming trees and shrubs, maintaining suitable habitat for grasses and grassland animals. Many species of birds and insects live in the savanna grasses. Which of the species or groups above would best be described as foundation species?

•  birds and insects
•  grasses
•  elephants
•  acacia trees

Feedback

Correct. Grasses are the most abundant organisms, are a key source of food, and make up the main physical structure of the savanna habitat.

Question 7

Points: 10 out of 10

What type of relationship exists between the hummingbird and the flower?

•  Mutualism
•  Predation
•  Competition

Feedback

Correct. The bird is able to gain nourishment from the nectar and the flower is pollinated.

Question 8

Points: 0 out of 10

Species richness is

•  The total weight, or biomass, of living organisms in a given area
•  The number of organisms in a community
•  The number of species in a population
•  The number of different species in an area

Feedback

Incorrect. Species richness is a measure of the number of species, not the number of individuals

Question 9

Points: 10 out of 10

The effect of wolves on the survival and growth of young trees along rivers in Yellowstone National Park is a good example of…

•  symbiosis.
•  a direct interspecific interaction.
•  an indirect interaction between two species.
•  predation.

Feedback

Correct. Wolves affect tree survival through their effect on a third species (grazers like elk).

Question 10

Points: 0 out of 10

In Africa, grasses are the main vegetation in savanna communities. Acacias and other trees are few and widely scattered. Elephants range over very large territories and are not very abundant in any one location. However, they strongly affect the community by uprooting and consuming trees and shrubs, maintaining suitable habitat for grasses and grassland animals. Many species of birds and insects live in the savanna grasses. Based on this information, which of the species or groups above would best be described as keystone species?

•  elephants
•  birds and insects
•  acacia trees
•  grasses

Feedback

Incorrect. Grasses are very abundant and therefore don’t qualify as keystone species.

Ecosystems Quiz

Schedule:

After deadline.Ended 02/28/2016 11:59 PM EST

Started:02/22/2016 9:43 AM EST

Submitted:02/24/2016 7:25 PM EST

Score:80%

Points:80 out of 100

Question 1

Points: 10 out of 10

Which of the four major biogeochemical cycles are significantly affected by human activities?

•  Nitrogen and phosphorus only
•  All of them (water, carbon, nitrogen, and phosphorus)
•  None of them
•  Water only
•  carbon only

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Correct. We influence all of these cycles.

Question 2

Points: 10 out of 10

Which human activity reduces transpiration and can reduce rainfall in the affected region?

•  buring fossil fuels
•  damming rivers
•  fertilizer use
•  deforestation

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Correct. Deforestation reduces plant cover, reduces transpiration, and can reduce regional rainfall levels.

Question 3

Points: 10 out of 10

A dog eats a pound of dog food. What happens to the energy and chemical nutrients in the food over the next several days?

•  Both the energy and nutrients are metabolized by the dog and are released as heat to the outside environment.
•  Both the energy and the nutrients become a permanent part of the dog’s ecosystem.
•  The energy is mostly released as heat through the dog’s activities; the nutrients either become part of the dog’s body or are released to the ecosystem as wastes like urine, feces, and exhaled gases.

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Correct. Energy dissipates as heat; nutrients are recycled.

Question 4

Points: 10 out of 10

Producers in a food chain are on which level of an energy pyramid?

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Correct. Producers make up the bottom of the energy pyramid.

Question 5

Points: 0 out of 10

Turkey vultures soar high in the sky until they detect dead animals with their supremely sensitive noses. They then swoop down and eat the dead flesh. Which of the following terms accurately describe turkey vultures? Select all that apply.

•  producers
•  consumers
•  detritivores
•  decomposers

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Incorrect. One or more of your selections is not characteristic of turkey vultures.

Question 6

Points: 10 out of 10

Adult largemouth bass eat smaller fish. These smaller fish eat a variety of foods. They eat some producers (algae) directly. They eat some zooplankton that are primary consumers. They also eat some predatory insects that are secondary consumers. Which option best describes the trophic level(s) of largemouth bass?

•  They are on trophic level 2
•  They are on trophic level 1
•  They are on trophic levels 2–4
•  They are on trophic levels 3–5
•  They are on trophic level 5

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Correct. When they eat primary consumers they are placed on level 3, but when their prey are at higher trophic levels they can be placed as high as level 5.

Question 7

Points: 10 out of 10

Which of the following consumers should be most abundant and most able to obtain an adequate food supply from a small area of habitat?

•  A primary consumer (level 2) such as a rabbit.
•  A secondary consumer (level 3) such as a rabbit-eating fox.
•  A tertiary consumer (level 4) such as a fox-eating eagle.

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Correct. This consumer is close to the base of the energy pyramid and has a lot of energy available to it.

Question 8

Points: 0 out of 10

Plants require phosphorus to build which kinds of macromolecules?

•  Proteins
•  carbohydrates
•  Nucleic acids, ATP, and phospholipids
•  All macromolecules (carbohydrates, lipids, nucleic acids, and proteins)

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Incorrect. Phosphorus is not required to make most proteins, lipids, or carbohydrates.

Question 9

Points: 10 out of 10

Which statement accurately describes one role of producers?

•  Producers consume dead organic matter and release the nutrients to make them available for othe