Question 1

In the 1930s, the Navajo Nation treated sheep and cattle for ticks and other parasites by using concrete "dip tanks," a common practice in the United States during that time period. Animals were herded into one end of the tank and out the other. Each day, the tanks were filled with 200,000 gallons of insecticide, and any remaining chemicals were emptied onto the ground. The pesticide solution seeped into the ground, ditches, and pits around the tanks.
In the 1990s, the EPA Emergency Response Team (ERT) was called to the Navajo Nation to investigate the problem. They concluded that bioremediation procedures were the best option for cleaning up the site. Certain types of bacteria are able to feed on and digest toxic organic substances, such as pesticides, and use them as fuel for cell respiration. The ERT distributed these pesticide-eating microorganisms throughout the contaminated soil to remove the chemical residues. Once the contaminants are degraded, these microorganism populations will die off because they will have used up all of their food supply.
-What evolutionary adaptations might the pesticide-eating bacteria have that allow them to be useful in this context? They likely
A) fed on pesticides present on the early planet Earth.
B) fed on the tissues and blood of cattle and sheep.
C) fed on biofilms that colonize anaerobic environments.
D) fed on molecules with a chemical structure similar to pesticides.

Accepted Answer

The pesticide-eating bacteria must have the ability to recognize and break down molecules with a chemical structure similar to pesticides in order to be useful in this context.

Question 2

Traditional microbial genomics and cultivation methods have given scientists access to approximately 1% of microbial genetic diversity. This is because most microbes cannot be grown up, or cultured, on petri dishes. Which scientific field would allow scientists to have a much greater access to an environment's genetic resources?
A) agriculture
B) forestry
C) bioremediation
D) metagenomics

Accepted Answer

Metagenomics involves analyzing the genetic material directly from environmental samples, without the need for cultivating the microbes first. This allows for a much greater access to the genetic diversity of an environment, as it includes microbes that cannot be grown using traditional methods. Agriculture and forestry may involve the study of microbes, but would not necessarily provide a greater access to the genetic resources of an environment. Bioremediation may involve the study of specific microbes for their ability to break down pollutants, but would not necessarily provide a greater access to the overall genetic diversity of an environment.

Question 3

Textile mills often release dye color and toxic by-products into rivers and streams, which may then taint groundwater. Fungi associated with mangrove trees have been shown to reduce both colors and toxicity in tainted groundwater.
-The fungi are being used as a form of
A) endosymbiosis.
B) bioremediation.
C) phagocytosis.
D) mixotrophy.

Accepted Answer

The passage suggests that the fungi associated with mangrove trees are being used to reduce colors and toxicity in tainted groundwater. This process is known as bioremediation, which involves the use of organisms to break down or remove pollutants from the environment. Endosymbiosis, phagocytosis, and mixotrophy are not mentioned in relation to this process.

Question 4

-Which of the following contains only protist clades?
A) SAR
B) Excavata
C) Unikonta
D) Archaeplastida

Accepted Answer

The answer of 
-Which of the following contains only protist...

Question 5

Alginates are used in many everyday products, including toothpaste and soap. When added to water, they form a thick gel that binds or emulsifies liquids. Alginates come from a group of multicellular stramenopiles that have one pigment that masks all others and therefore gives these organisms a distinctive, dark color. Alginates are derived from
A) green algae.
B) brown algae.
C) water molds.
D) dinoflagellates.

Accepted Answer

Alginates are derived from brown algae, also known as Phaeophyceae. They are commonly found in kelp forests and rocky intertidal zones.

Question 6

A negative impact of biofilms in the human body is that biofilms can cause head and neck diseases. A study was completed that compared three groups of medical patients for presence or absence of biofilms. Group 1 were patients with chronic otitis media (COM), a disease where the eardrum continually drains and can often become clogged, that also displayed ear discharge. Group 2 were COM patients without ear discharge. Group 3 were patients undergoing surgery for cochlear implantation, a procedure where a small electronic instrument is placed in the ear to carry out normal functions of the inner ear. Two microscopy methods were used to detect presence of biofilms in all patients of both groups: direct microscopy (DM) and transmission electron microscopy (TEM).
The table below shows the results of presence or absence of biofilms in all study participants.
Table 1. Number of study participants detected with biofilms
 $$\begin{array} { | l | l | l | l | } 
\hline \text { Group } & \text { Group Size } & \text { Biofilm on DM } & \text { Biofilm on TEM } \
\hline 1 \text { COM, discharge } & 10 & 10 & 10 \
 \hline 2\text { COM no discharge } & 9 & 2 & 2 \
 \hline3 \text { B cochlear implant } & 10 & 0 & 0 \
\hline \text { Total } & 29 & 12 & 12 \
\hline
\end{array}$$ Source: Adapted from Akyıldız, I., Take, G., Uygur, K., Kızıl, Y., & Aydil, U. (2013). Bacterial biofilm formation in the middle-ear mucosa of chronic otitis media patients. Indian J Otolaryngol Head Neck Surg, 557-561. doi:10.1007/s12070-012-0513-x
-Which group served as the control group in the experiment?
A) 1
B) 2
C) 3

Accepted Answer

Group 3, the patients undergoing surgery for cochlear implantation, served as the control group because they were not experiencing chronic otitis media (COM), unlike Groups 1 and 2, and were undergoing a different type of ear surgery that did not involve the conditions being directly studied (COM with and without discharge). This makes them a baseline for comparison to understand the impact of biofilms in COM.

Question 7

Some current research efforts are investigating whether or not ________, a group of prokaryotes with the ability to produce oxygen as a by-product of photosynthesis, can be used as a source of renewable energy by converting sunlight into electricity.
A) chlamydias
B) spirochetes
C) proteobacteria
D) cyanobacteria

Accepted Answer

Cyanobacteria are known for their ability to produce oxygen through photosynthesis and are being researched as a potential source of renewable energy. They have been shown to be capable of generating electricity in microbial fuel cells, making them a promising candidate for sustainable energy production. Chlamydias, spirochetes, and proteobacteria do not have the same ability to produce oxygen as a by-product of photosynthesis, making them less likely to be used as a source of renewable energy in this way.

Question 8

A negative impact of biofilms in the human body is that biofilms can cause head and neck diseases. A study was completed that compared three groups of medical patients for presence or absence of biofilms. Group 1 were patients with chronic otitis media (COM), a disease where the eardrum continually drains and can often become clogged, that also displayed ear discharge. Group 2 were COM patients without ear discharge. Group 3 were patients undergoing surgery for cochlear implantation, a procedure where a small electronic instrument is placed in the ear to carry out normal functions of the inner ear. Two microscopy methods were used to detect presence of biofilms in all patients of both groups: direct microscopy (DM) and transmission electron microscopy (TEM).
The table below shows the results of presence or absence of biofilms in all study participants.
Table 1. Number of study participants detected with biofilms
 $$\begin{array} { | l | l | l | l | } 
\hline \text { Group } & \text { Group Size } & \text { Biofilm on DM } & \text { Biofilm on TEM } \
\hline 1 \text { COM, discharge } & 10 & 10 & 10 \
 \hline 2\text { COM no discharge } & 9 & 2 & 2 \
 \hline3 \text { B cochlear implant } & 10 & 0 & 0 \
\hline \text { Total } & 29 & 12 & 12 \
\hline
\end{array}$$ Source: Adapted from Akyıldız, I., Take, G., Uygur, K., Kızıl, Y., & Aydil, U. (2013). Bacterial biofilm formation in the middle-ear mucosa of chronic otitis media patients. Indian J Otolaryngol Head Neck Surg, 557-561. doi:10.1007/s12070-012-0513-x
-How can you interpret results of the study?
A) All patients with a history of ear discharge and two without ear discharge were found by DM and TEM to have presence of biofilms.
B) All cochlear transplant patients were found by DM to have presence of biofilms.
C) Half of the patients with ear discharge were found to be free of biofilms.
D) Cochlear transplant patients were found to have more occurrences of biofilms than all other study patients.

Accepted Answer

All patients in Group 1 (COM with discharge) were found to have biofilms using both microscopy methods, and only 2 patients in Group 2 (COM without discharge) were found to have biofilms, indicating that biofilms were present in all patients with ear discharge and in some without.

Question 9

Some white blood cells are able to surround and ingest bacteria. Which of the following would you expect to see as part of the blood cell structure?
A) secondary cell walls
B) flagella
C) pseudopodia
D) cilia

Accepted Answer

Pseudopodia are cellular extensions that allow cells, including some white blood cells, to move and engulf bacteria. Secondary cell walls, flagella, and cilia are not present in white blood cells.

Question 10

If you place an organism classified as a photoautotroph at the bottom of a lake and later see that it is able to acquire nutrients from dead plant material, you can conclude the photoautotroph is actually a
A) photoheterotroph.
B) chemoautotroph.
C) chemoheterotroph.
D) mixotroph.

Accepted Answer

A mixotroph is an organism that can obtain nutrients through both phototrophic and heterotrophic means. In this scenario, the organism was initially classified as a photoautotroph, but is now also obtaining nutrients from dead plant material, indicating that it can also act as a heterotroph. This fits the definition of a mixotroph.

Question 11

Dunaliella salina is a bacterium that is able to live in aqueous solutions with such high salt concentrations that the salt cannot fully dissolve. D. salina is an example of a(n)
A) extreme thermophile.
B) extreme halophile.
C) methanogen.
D) proteobacteria.

Accepted Answer

Dunaliella salina is able to live in extremely high concentrations of salt, making it an extreme halophile. It is not an extreme thermophile, methanogen, or proteobacteria.

Question 12

-Which stage of the life cycle of Ulva shown is the sporophyte?
A) stage A
B) stage B
C) stage C
D) stage D

Accepted Answer

The answer of 
-Which stage of the life cycle of...

Question 13

A negative impact of biofilms in the human body is that biofilms can cause head and neck diseases. A study was completed that compared three groups of medical patients for presence or absence of biofilms. Group 1 were patients with chronic otitis media (COM), a disease where the eardrum continually drains and can often become clogged, that also displayed ear discharge. Group 2 were COM patients without ear discharge. Group 3 were patients undergoing surgery for cochlear implantation, a procedure where a small electronic instrument is placed in the ear to carry out normal functions of the inner ear. Two microscopy methods were used to detect presence of biofilms in all patients of both groups: direct microscopy (DM) and transmission electron microscopy (TEM).
The table below shows the results of presence or absence of biofilms in all study participants.
Table 1. Number of study participants detected with biofilms
 $$\begin{array} { | l | l | l | l | } 
\hline \text { Group } & \text { Group Size } & \text { Biofilm on DM } & \text { Biofilm on TEM } \
\hline 1 \text { COM, discharge } & 10 & 10 & 10 \
 \hline 2\text { COM no discharge } & 9 & 2 & 2 \
 \hline3 \text { B cochlear implant } & 10 & 0 & 0 \
\hline \text { Total } & 29 & 12 & 12 \
\hline
\end{array}$$ Source: Adapted from Akyıldız, I., Take, G., Uygur, K., Kızıl, Y., & Aydil, U. (2013). Bacterial biofilm formation in the middle-ear mucosa of chronic otitis media patients. Indian J Otolaryngol Head Neck Surg, 557-561. doi:10.1007/s12070-012-0513-x
-What can you conclude from the study?
A) If ear discharge is treated with a lose-dose antibiotic, COM will not be established in a patient.
B) Treatment for patients with COM may be challenging due to the presence of biofilms.
C) Cochlear ear transplant patients should be concerned about contracting COM.
D) Biofilms are naturally present in the human ear.

Accepted Answer

The presence of biofilms in all patients with chronic otitis media (COM) with discharge (Group 1) and in some patients with COM without discharge (Group 2) but not in patients undergoing cochlear implantation (Group 3) suggests that biofilms are associated with COM and may contribute to its persistence, making treatment challenging.

Question 14

Which of the following statements regarding Ulva is true?
A) Ulva, a brown algae, resembles land plants because it produces diploid gametes.
B) Ulva, a brown algae, has a complex life cycle with diploid body cells and haploid gametes.
C) Ulva, a green algae, has a complex life cycle with diploid body cells and haploid gametes.
D) Ulva, a green algae, has a complex life cycle with alternation between multicellular diploid and haploid generations.

Accepted Answer

Ulva is a green algae known for its alternation of generations, where it alternates between multicellular diploid (sporophyte) and haploid (gametophyte) stages.

Question 15

Textile mills often release dye color and toxic by-products into rivers and streams, which may then taint groundwater. Fungi associated with mangrove trees have been shown to reduce both colors and toxicity in tainted groundwater.
-Suppose that fungal treatment was added to stream water contaminated from a textile mill. The toxins in the water tend to lower pH levels, and scientists wanted to study how adding the fungal treatment affected stream pH levels. pH levels were recorded every year for five years. Results indicated that the acidity of the stream water decreased from pH 2.5 in the first year to pH 5.9 by the fifth year. Scientists concluded that
A) the fungal treatment had little to no effect on detoxifying the stream water.
B) the fungal treatment had a positive effect on detoxifying the stream water.
C) the fungal treatment had completely detoxified the stream water.
D) there was not enough evidence to determine the effects of the fungal treatment on the toxic stream water.

Accepted Answer

The decrease in acidity from pH 2.5 to pH 5.9 over five years indicates that the fungal treatment had a positive effect on detoxifying the stream water. However, it did not completely detoxify the water, as the pH level was still below neutral after five years. Therefore, choice B is the best answer.

Question 16

Compost piles create an intense heat source and would therefore be suitable environments for
A) extreme thermophiles.
B) extreme halophiles.
C) methanogens.
D) proteobacteria.

Accepted Answer

Compost piles can reach temperatures of over 70°C, which is suitable for extreme thermophiles.

Question 17

Someone diagnosed with meningitis has inflamed membranes that cover and protect the brain and spinal cord. Meningitis is a result of pathogenic gram-negative bacteria that cause extreme infections when their bacterial cell wall dies and lipopolysaccharide (a lipid and polysaccharide) is released. The lipopolysaccharide is an example of a(n)
A) endotoxin.
B) exotoxin.
C) stomach microbiota.
D) parasite.

Accepted Answer

Lipopolysaccharide is a component of the cell wall of gram-negative bacteria and is released when the bacterial cell wall dies, making it an endotoxin.

Question 18

-How do you characterize SAR, Excavata, Unikonta, and Archaeplastida?
A) They are all protist clades.
B) They are all nonprotist clades.
C) They are all eukaryote supergroups.
D) They are all diatoms.

Accepted Answer

SAR, Excavata, Unikonta, and Archaeplastida are all eukaryote supergroups, as indicated by the figure.

Question 19

-Which group has the least scientific support for its position in the phylogeny?
A) SAR, because the phylogeny indicates that stramenopiles, alveolates, and rhizarians have only partial scientific support of evolutionary relationships.
B) Excavata, because the phylogeny indicates this group is not related to any other group in the phylogeny.
C) Unikonta, because the phylogeny indicates that fungi and animals are only partially evolutionarily related to one another.
D) Archaeplastida because the phylogeny indicates that red and green algae have stronger relationships with one another than with land plants.

Accepted Answer

The phylogeny indicates that SAR (stramenopiles, alveolates, and rhizarians) have only partial scientific support of evolutionary relationships.

Question 20

In the 1930s, the Navajo Nation treated sheep and cattle for ticks and other parasites by using concrete "dip tanks," a common practice in the United States during that time period. Animals were herded into one end of the tank and out the other. Each day, the tanks were filled with 200,000 gallons of insecticide, and any remaining chemicals were emptied onto the ground. The pesticide solution seeped into the ground, ditches, and pits around the tanks.
In the 1990s, the EPA Emergency Response Team (ERT) was called to the Navajo Nation to investigate the problem. They concluded that bioremediation procedures were the best option for cleaning up the site. Certain types of bacteria are able to feed on and digest toxic organic substances, such as pesticides, and use them as fuel for cell respiration. The ERT distributed these pesticide-eating microorganisms throughout the contaminated soil to remove the chemical residues. Once the contaminants are degraded, these microorganism populations will die off because they will have used up all of their food supply.
-The bacteria used in this bioremediation procedure are
A) chemoautotrophs.
B) photoautotrophs.
C) chemoheterotrophs.
D) photoheterotrophs.

Accepted Answer

The bacteria used in the bioremediation procedure are able to feed on and digest toxic organic substances, which indicates they are chemoheterotrophs. Chemoautotrophs and photoautotrophs are not able to perform this function, and photoheterotrophs rely on light as a source of energy, which is not relevant in this context.

Quiz 16: Microbial Life: Prokaryotes and Protists

Textile mills often release dye color and toxic by-products into rivers and streams, which may then taint groundwater. Fungi associated with mangrove trees have been shown to reduce both colors and toxicity in tainted groundwater. -The fungi are being used as a form of

-Which of the following contains only protist clades?

Some current research efforts are investigating whether or not ________, a group of prokaryotes with the ability to produce oxygen as a by-product of photosynthesis, can be used as a source of renewable energy by converting sunlight into electricity.

Some white blood cells are able to surround and ingest bacteria. Which of the following would you expect to see as part of the blood cell structure?

If you place an organism classified as a photoautotroph at the bottom of a lake and later see that it is able to acquire nutrients from dead plant material, you can conclude the photoautotroph is actually a

Dunaliella salina is a bacterium that is able to live in aqueous solutions with such high salt concentrations that the salt cannot fully dissolve. D. salina is an example of a(n)

-Which stage of the life cycle of Ulva shown is the sporophyte?

Which of the following statements regarding Ulva is true?

Compost piles create an intense heat source and would therefore be suitable environments for

-How do you characterize SAR, Excavata, Unikonta, and Archaeplastida?

-Which group has the least scientific support for its position in the phylogeny?