Members of which two bacterial phyla shown below are most commonly found in both
ID: 180088 • Letter: M
Question
Members of which two bacterial phyla shown below are most commonly found in both freshwater lakes and terrestrial soils?
A. Proteobacteria
B. Cyanobacteria
C. Acidobacteria
D. Actinobacteria
E. Bacteroidetes
Microbial species diversity tends to be
A. high in communities under stress
B. low in physically controlled environments
C. seems to be unrelated to community productivity
D. high in biologically controlled habitats
What physiological characteristics are most commonly found in cultured members of the archaeal Domain of prokaryotic microorganisms?
A. halophily
B. hyperthermophily
C. methanogenesis
D. nitrogen fixation
E. methane oxidation
Which statement is false?
A. It is less expensive to sequence a hundred thousand smaller DNA fragments using the Illumina sequencing method than it is to prepare and sequence 100 to 200 DNA fragments using the Sanger sequencing method.
B. An advantage of next generation sequencing methods is the more detailed taxonomic information that it is possible to obtain about the individual microbes in natural communities.
C. The rate-limiting step in exploring the diversity of bacterial communities using DNA sequencing used to be the labor involved in preparing clone libraries but now it is the post-sequencing analysis of massive amounts of DNA sequence data.
D. Next generation sequencing methods allow microbial ecologists to obtain data sets that are more representative of the true diversity of microbial communities and probably detect more rare microbes than using traditional cloning and Sanger sequencing techniques.
E. Metagenomics can be used to detect metabolic flexibility in bacterial groups.
Which of these microorganism-organism pairs are examples of mutualistic relationships? (circle all correct answers)
A. Frankia – common alder E. sulfur-oxidizing bacteria – Riftia
B. Vibrio fischeri – squid F. Zooxanthellae – coral
C. Bradyrhizobium – cyanobacteria G. Bacteroides – humans
D. fungi – green algae H. Pseudomonas – soybeans
Explanation / Answer
I. Cyanobacteria is present in all habitats and biomes on earth. Acidobacteria is the most abundant bacterial phylum in many soils. The primary habitat of Actinobacteria is soil, they are also common in fresh water habitats and other aquatic environments like rivers, brackish seas, bays and glacial ice. Bacteriodetes occur in soil, in aquatic environments, or as symbionts of plants, animals, and humans. Proteobacteria is found in lakes/pond (alphaproteobacteria), fresh/ waste water/soil (betaproteobacteria) or intestinal tracts (gammaproteobacteia). The most commonly found two phylla can be attributed to Cyanobacteria and Actinobacteria.
IV. Mutualistic relationships is shown by A,B,D, E, F, G and H
II. A study on biological diversity among bacterial, fungal and ant communities in small road medians, larger parks across Manhattan (NYC) showed that microbial diversity and composition was less sensitive to urban stress than those of macroorganisms. Microbes and their associated ecosystem services and functions showed more resilience to the negative effects of urbanization. In a study on freshwater protozoan communities it was observed that stress distorts the distribution of species within the community by eliminating the sensitive ones and increasing the tolerating ones, thereby greater proportion of tolerant ones but with lower diversity as a whole. Generally diversity increases ecosystem productivity over short timescales.
Considering these conclusions it can be infered that the microbial species diversity tends to be low in physically controlled environments.
III. Archaea domain is pathogenic and many members live in extreme environments. Halophyles are commonly grown in hypersaline media. it seems halophily is the most common physiological character found in cultured members of Archae domain.