All GRE Subject Test: Biology Resources
Example Questions
Example Question #2 : Understanding Population Ecology
There are several different kinds of survivorship curves for different kinds of animals. What kind of survivorship curve do organisms with little to no parental care generally exhibit?
Very old individuals
Type III: high initial mortality
Type II: constant mortality rate
Type I: high advanced age mortality
An intermediate between types I and II
Type III: high initial mortality
Organisms with little to no parental care typically have large amounts of offspring to compensate for high mortality rates of the young, as shown in a type III survivorship curve. These include organisms like trees, which spread large numbers of seeds because the seeds rarely find a good growing spot and mature to adulthood.
Example Question #12 : Ecology
Which of the following best defines the interspecies interaction in the following situation?
Jackrabbit populations introduced to the Australian outback from Europe in the 1800s decimate communities of desert shrubs and grasses.
Predation
Parasitism
Amensalism
Mutualism
Commensalism
Amensalism
The over-browsing by the invasive jackrabbit population has resulted in harm being done to the desert plant communities with no negative impact on the rabbits, resulting in amensalism.
Example Question #11 : Organismal Ecology
Hummingbirds use their long beaks to drink nectar from flowers. In turn, they carry the pollen from flower to flower, assisting the reproduction of the flowers.
What relationship does this describe?
Competitive Exclusion
Resource Partitioning
Parasitism
Mutualism
Co-evolution
Mutualism
Coevolution is a process by which two or more species evolve in response to one another, and generally describes competing species. While the hummingbird and the flower may evolve due to this relationship, coevolution more freqeucntly describes the evolution of defense mechanisms in response to a predator-prey relationship. Parasitism is the relationship in which one species benefits at the expense of the host. This can sometimes lead to coevolution, depending on how the host reacts. Neither species is being harmed in the given scenario, so this is incorrect. Commensalism is when one species benefits, but the other species is not impacted. In this case, both the hummingbird and the flower are benefiting, so this is not our answer. Resource partitioning is when species evolve together to share resources in a sustainable way. The hummingbird is using a resource that the flower provides, but they are not "sharing" in the sense of the definition of resource partitioning. Competitive exclusion describes the phenomenon when two species share the same niche, and the stronger one forces out the weaker competitor.
Mutualism, the correct answer, describes a relationship wherein species exploit each other mutually. In this case, the hummingbird gains nutrition from the flower, and the flower gains a reproductive advantage from the hummingbird.
Example Question #1 : Understanding Community Ecology
When measuring biodiversity, there are several possible indices to use, such as alpha diversity or beta diversity. What does beta diversity, or species evenness, measure?
The diversity of the entire geographic area
The number of individuals in a population
The species richness in a patch of uniform habitat
The number of individuals per square kilometer
The rate of change in species composition from one habitat to the next
The rate of change in species composition from one habitat to the next
Beta diversity measures the rate of change in the species composition of one habitat as compared to others. This is called the species evenness of an area. For instance, if one habitat has radically more species than a neighboring habitat, this would result in a high beta diversity. Alpha diversity is measured as the number of species in a uniform area, and gamma diversity is the species richness in a range of habitats (a mix of alpha and beta).
Example Question #1 : Understanding Trophic Energy
A bacterium is found to survive off of organic molecules created by other organisms. It relies on these as both carbon and energy sources. Which term best describes this bacterium?
None of these
Chemoautotroph
Chemoheterotroph
Photoheterotroph
Photoautotroph
Chemoheterotroph
Autotrophs use for their carbon source, while heterotrophs use organic compounds from other organisms. Chemotrophs use chemical bonds as their energy source, while phototrophs use light. Combining these ideas we can come up with various terms to describe an organism's nutrition. The bacterium in this question stated to rely on organic chemicals from other organisms as a carbon and energy source. This makes it a chemoheterotroph.
Example Question #14 : Ecology
The phosphorus cycle is fundamentally different from the nitrogen and sulfur cycles. How so?
Phosphorus is not fixed in the atmosphere by lightning.
Phosphorus is not taken up by plants and is a strictly inorganic cycle.
Phosphorus is cycled back into the soil through precipitation.
The phosphorus cycle does not include a gaseous phase, resulting in no significant quantities of atmospheric phosphorus.
Phosphorus does not enter the cycle from weathering of sediments and parent material.
The phosphorus cycle does not include a gaseous phase, resulting in no significant quantities of atmospheric phosphorus.
The phosphorus cycle does not contain an atmospheric phase, while both the sulfur and nitrogen cycles do.
Example Question #15 : Ecology
Which of the following provides the most accurate example of primary succession?
Lichens re-establish themselves on rocks and shallow soil beds following a tundra fire
Coral reef and aquatic wildlife communities that have re-established themselves in regions of the South Pacific that were evacuated following the nuclear tests conducted by the U.S. military
Native grass communities forming after a wildfire burned through a meadow/woodland ecosystem
Lichen and grass communities establishing themselves on a recently-formed island, resulting from an uplift in the ocean bedrock
Seedlings establishing themselves in a heavily logged area where the seed-tree cutting method was employed
Lichen and grass communities establishing themselves on a recently-formed island, resulting from an uplift in the ocean bedrock
Primary succession is characterized by plants establishing themselves in areas that were initially devoid of soil (usually bedrock). Grasses establishing themselves on a newly-formed island that is mostly bedrock is the best fit for this definition.
Example Question #1 : Ecological Succession
Which of the following would NOT contribute significantly to primary succession?
Wind-carried soil particles and nutrients
The time-consuming process of weathering the bedrock into smaller particles
Pre-existing nitrogen-fixing plant communities
Feces from wildlife populations that occupy the region
Soil nutrients deposited by a nearby river
Pre-existing nitrogen-fixing plant communities
Primary succession is characterized by pioneer species establishing themselves in areas that are predominantly bedrock and devoid of organic material. The formation of organic material in these areas typically occurs with the accumulation of wind-carried soil erosion, nutrients deposited by flowing bodies of water, and erosion of bedrock. Wildlife populations are also a significant contributor of soil nutrients, with feces being rich in both nitrogen and phosphorus. In contrast, pre-existing nitrogen-fixing plants (or any pre-existing plant communities) are uncommon to nonexistent in an area with no established soil system.
Example Question #1 : Evolution And Mutations
Which type of mutation creates a premature stop codon in the mRNA?
Missense mutation
Nonsense mutation
Frameshift mutation
Silent mutation
Nonsense mutation
While a missense mutation involves substituting a base pair, resulting in a new amino acid, a nonsense mutation takes place when the new substituted codon is a stop codon. This causes the protein to stop being translated prematurely. Because of their impact on protein production, nonsense mutations very commonly prevent the formation of a functional protein.
Silent mutations result in no change in primary protein structure. Due to the degeneracy of the genetic code, a mutation can occur without changing the identity of the amino acid recruited during translation. A frameshift mutation results in a shift in the codon reading frame, severely altering the primary protein structure and often resulting in a truncated protein.
Example Question #1 : Mutations And Variability
A __________ mutation always results in the ribosome encountering a premature stop codon.
deletion
nonsense
missense
frameshift
nonsense
Nonsense mutations are the name specifically given to mutations that cause the ribosome to encounter a premature stop codon and terminate translation early. A point mutation causes the transcription of a stop codon by changing the DNA transcript transcribe to the mRNA stop codons UAG, UAA, or UGA. Placement of this codon in the transcript will interrupt translation.
Missense mutations are a type of mutation that result in the inclusion of a different amino acid than the wild type protein. Frameshift mutations result in a change to the codon reading frame, and are typically caused by deletion or insertion mutations. Frameshift mutations have the most dramatic and detrimental effect on proteins. Deletion mutations result from removal of one or more base pairs.
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