Exam 1 Questions

Question 1

(T/F)

High pressure has the same effects on cellular membranes as does low temperature.

Answer 1

True

Question 2

(T/F)

The 16s rRNA molecule can be used to determine what microbes are active within an environment.

Answer 2

False

The MRNA molecule…

Question 3

(T/F)

Aquatic environments tend to be well-mixed.

Answer 3

False

…tend to NOT BE well-mixed

Question 4

(T/F)

A rarefraction analysis can be used to compare richness among sampling sites that have been unequally sampled.

Answer 4

True

Question 5

(T/F)

The benthic zone is at the bottom of the water column, and has a low concentration of organisms and nutrients.

Answer 5

False

…has a HIGH concentration of organisms and nutrients

Question 6

(T/F)

The cation exchange capacity of soils with high clay content is low because of negative charges associated with clays

Answer 6

False

…high clay content is HIGH because of…

Question 7

(T/F)
The Biological Pump refers to the ocean’s biologically-driven sequestration of carbon from the atmosphere to the deep sea.

Answer 7

True

Question 8

(T/F)
An autotroph utilizes carbon dioxide as a carbon source and a heterotroph utilizes organic compounds as a carbon source.

Answer 8

True

Question 9

(T/F)

The stable isotope method is used to characterize the diversity of microbial communities.

Answer 9

False

…characterize the ACTIVITY of microbial communities

Question 10

(T/F)

A microbial mat is a vertically-stratified biofilm that is often associated with extreme environments.

Answer 10

True

Question 11

(T/F)

Direct microscopic counts using fluorescent dye (such as DAPI) will be equal to viable cell counts.

Answer 11

False

…will be UNEQUAL to viable cell counts

Question 12

(T/F)
If you isolated an organism from a psychrophilic environment and assayed the membrane, you would likely find an increase in the average fatty acid chain length in comparison to mesophiles.

Answer 12

False

…an organism from a THERMOPHILIC environment…

Question 13

(T/F)
Microbial ecology is the study microbes within all habitats and their beneficial and detrimental impacts on human health and welfare.

Answer 13

False

ENVIRONMENTAL BIOLOGY is the study of…

Question 14

(T/F)

The results of a DNA-DNA re-association analysis will be indirectly proportional to species diversity.

Answer 14

True

Question 15

(T/F)

Microorganisms adapted to high UV environments often contain more than one copy of their genome.

Answer 15

True

Question 16

(T/F)
The Neuston layer is considered by many to be an extreme environment because of the potential for the accumulation of toxic substances.

Answer 16

True

Question 17

List (3) strengths of the RNA World theory for the evolution of information processing in cells:

Answer 17

A.) RNA can serve as genetic material
B.) 16s rRNA is present amongst all organisms
C.) RNA is more reactive than DNA

Question 18

What is the important of the “microbial loop” in aquatic environments?

Answer 18

Important for nutrient cycling

nutrients (go into) –> ocean/atmosphere (uptaken by) –> phytoplankton (food) –> heterotrophs (secretes) –> nutrients (beginning)

(can refer to valerie’s drawing #2)

Question 19

Distinguish between the biological species concept as applied to plants and animals and the operational taxonomic unit (OTU) concept that can be applied to Bacteria and Archaea.

Answer 19

The Biological Species Concept focuses on organisms’ ability to reproduce (which doesn’t take into account for asexual microbes).
The OTU Concept incorporates a more molecular approach to microbes since it focuses on organisms’ taxonomy, abundance, and genome similarities/differences.

Question 20

List (3) reasons why ribosomal RNAs are ideal molecular chronometers:

Answer 20

A.) All organisms have the 16s rRNA molecule
B.) 16s rRNA molecule is highly conserved in many regions (doesn’t change much)
C.) 16s rRNA is variable in some regions (allows us to determine differences & similarities with other organisms)

Question 21

What are (3) key roles that microorganisms play in soil ecosystems?

Answer 21

A.) They can alter the microenvironment/habitat of the soil they live in
B.) They are important for nutrient cycling (1* producers/2* consumers)
C.) They can affect the stratification of the soil layers (surface vs sub-surface layers)

Question 22

Explain the difference in GC content observed in the DNA extracted from thermophilic organisms versus DNA extracted from halophilic organisms.

Answer 22

You would think that thermophiles have a high GC content, but they’re actually AT-rich. They have a lot of proteins (ex: histones) that bind and protect thermophilic DNA from denaturing.
Halophiles have a higher GC content in their DNA to help overcome their harsh (high salt) environment.

Question 23

List (3) adaptations seen in proteins from high temperature environments:

Answer 23

A.) Less and shorter loops
B.) Less cavities
C.) Less binding/interactions within chains (ex: ionic)

Question 24

What are (3) weaknesses (or remaining questions) of the Miller-Urey experiment:

Answer 24

A.) How can they be sure of the composition of the early atmosphere
B.) How were molecules able to polymerize amidst the aquatic environment if protein polymerization requires hydrolysis
C.) Stereoisomers of molecules dictate if they will polymerize or not

Question 25

What are (3) functions of viruses in aquatic systems?

Answer 25

A.) Lyse 2* consumers to release nutrients
B.) Assist in carbon sequestration
C.) Assist in nutrient cycling

Question 26

List the steps involved in formation of a biofilm:

Answer 26

1. ) a single microbe adheres to a surface
2. ) more microbes come and adhere to that surface and begin to interact with each other
3. ) phase 1: microbes begin to secrete exopolysaccharides = begins the formation of a biofilm = reversible
4. ) phase 2: biofilm structure becomes stronger and thicker = irreversible
5. ) mature biofilm