BIO 115 Exam 3
What is the "biodiversity crisis"?
A significant percentage of species that are endangered or threatened, if not extinct in the wild
Based on the phylogenetic tree showing the evolutionary relationships among annelids, which of the following collection of lineages form a monophyletic group within the annelids?
Acantobdellida, Branchiobdellida, and Hirudinea Correct! These three groups can be traced back to a common ancestor, and that common ancestor's only descendants are these three groups.
Why is bacterial conjugation relevant to the medical field?
Antibiotic resistance can spread in a population by conjugation Correct! If an F plasmid contains an antibiotic resistance gene, it will be transferred to the other cell during conjugation along with the plasmid.
Which of the following is the broadest taxonomic group (i.e. which answer includes the other answers as subgroups)?
Archaeplastida Correct! This group includes all eukaryotics that descend from the ancestor where primary endosymbiosis occurred. This includes red algae, green algae, and plants
You are tasked with culturing a chemoautotrophic bacteria that metabolizes ammonia into nitrite in order to make ATP. Which of the following resources does it NOT need to survive?
Complex organic molecules Correct! It's energy comes from chemical reactions converting ammonia to nitrate (chemotrophic could also cover the use the chemical bonds in organic molecules for energy, but this species in this question is described as using ammonia, not organic molecules). Autotrophic means that it can use single-carbon molecules like carbon dioxide to build organic molecules, and doesn't need to ingest pre-existing carbon-carbon bonds.
The table below is from a study on fecal transplant as a treatment of recurrent C-diff infections. What role do the factors in the table play in the study?
Controlled variables Correct! These are all potentially confounding factors, and the researchers are making sure that these factors are the same across the treatment groups.
Is photosynthesis homologous or convergent in protists?
Convergent - different lineages of protists acquired the ability to photosynthesize independently Homologous - all chloroplasts in protist can be traced back to a single instance of endosymbiosis of a cyanobacterium It is true that the common ancestor of all photosynthetic protists was not photosynthetic. Therefore, each photosynthetic lineage became photosynthetic independently. It is also true that the endosymbiotic event that gave rise to chloroplasts, which makes photosynthesis possible, occurred only once. The chloroplasts was then acquired by other lineages through secondary and tertiary endosymbiosis.
Which of the following is a good way to preserve genetic variation in endangered populations?
Create conservation area with the largest size possible Correct! The larger size will support a larger population, minimizing genetic drift and its reduction of genetic variation.
How does the current concentration of carbon dioxide in the atmosphere compare to historical concentrations.
Currently much higher than it has ever been in the past 800,000 years
Based on the theory of endosymbiosis, would you predict that the DNA sequence of a gene in the chloroplasts of green algae would most similar to the sequence of gene in...
Cyanobacteria Correct! The chloroplasts of green algae are the result of primary endosymbiosis involving cyanobacteria. The chloroplasts were once free-living cyanobacteria, and so are most genetically similar to current cyanobacteria
Which of the following is an accurate differences between prokaryotic and eukaryotic cells?
Eukaryotic cells have nuclei, prokaryotic cells do not
Which of the following is NOT an example of an ecosystem service?
Gypsy moth caterpillers defoliating trees in New England.
If humans were to immediately eliminate all carbon dioxides contributions from farming and burning plant matter, how would that affect the concentration of carbon dioxide in the atmosphere?
It would continue to increase.
Below is a phylogenetic tree showing the evolutionary relationships among groups of annelids, with the evolution of several traits marked on the tree. Which of the following traits is NOT an example of a homology within the annelids?
Loss of setae Loss of setae appears twice on the phylogenetic tree, meaning that this trait evolved more than once and is not homologous
Which of the following is NOT evidence supporting the theory of endosymbiosis?
Mitochondria have their own nucleus Correct! Mitochondria do not have nuclei, in part because the free-living, prokaryotic bacteria they evolved from do not have nuclei
You are studying a species of bacteria that requires light and access to complex organic molecules to grow. It cannot survive only on carbon dioxide (CO2). Which term best describes its metabolic strategy?
Photoheterotrophic Correct! This metabolic strategy captures solar energy (light) to acquire energy for itself, and takes in pre-existing carbon-carbon bonds in order to make its own building material
Which of the following taxonomic ranks is the most inclusive (potentially includes the most species)
Phylum Correct! All of the the other choices are subgroups with in phyla. A phylum would include the widest variety of species.
Which of the following is NOT a step in the extinction vortex?
Population will have harmful traits selected for by natural selection Correct! Natural selection may be weakened by lack of variation, or be overpowered by strong drift in very small populations. However, natural selection itself will never directly select for or increase the frequency of harmful traits.
Which of the following is an accurate statement about the 3 domains of life?
Some prokaryotic organisms are as different from each other as they are from eukaryotic organisms Correct! Two of the three domains consist of prokaryotes.
Hypothetical data on the stomatal density and cuticle thickness of three plant species is given below. Which plant species is most likely to be a desert-dwelling species? Species A 121 stomatal density 4.3 cuticle thickness Species B 57 stomatal density 6.2 cuticle thickness Species C 52 stomatal density 12.6 cuticle thickness
Species C Correct! Species C has a reduced number of openings, and a thick wax layer sealing the leaves
What feature or features of land plants were made possible by the evolution of delayed meiosis?
Sporophytes Stems Correct! The delayed meiosis means that the diploid zygote can divide mitotically into a multicellular diploid stage (sporophyte). If delayed long enough, the mitosis can produce a stem that raises the sporangia up above the gametophyte. Although not listed, the embryo is another feature of land plants made possible by delayed meiosis.
What is the difference between a sporophyte and gametophyte?
Sporophytes are diploid and generate spores, gametophytes are haploid and generate gametes
Why is a family member that lives with you the best source for a stool sample for fecal transplant?
That person likely has a similar healthy gut flora as you do Correct! The goal is to re-populate the natural gut microbiome, and a person living with would likely have a similar natural microbiome
What role do bacteria that utilize nitrogen in energy acquisition play in ecosystems?
The help cycle nitrogen in ecosystems, converting it into forms that certain plant species can utilize. Correct! Conversion of nitrogen from one from to another as it moves through the nitrogen cycle is almost entire done by various prokaryotes. They are the drives of the nitrogen cycle.
Why are small, isolated populations at greatest risk of extinction?
They experience more genetic drift and less gene flow Correct! They are small (more genetic drift) and isolated (less gene flow), and this combination of evolutionary mechanisms is going to lead to the greatest decrease in genetic variation.
Once inside a hot cell, what does a virus first do during a lytic cycle?
Use the host cells' ribosomes to make more virus capsid proteins
Which type of vaccine requires certain viral genes (such as for a spike protein in a viral capsid) to be incorporated into genome of the individual receiving the vaccine?
Virus vector vaccine Correct! These vaccines carry the gene for the spike protein inside a virus capsid. The virus brings the gene into a person's cell, and the gene is incorporated into the cells DNA. It will then be used to make the spike proteins the immune system will learn to recognize.
