MicroEco Prelims (Objective Type)

What is the etymological origin of the term 'ecology'? A) Latin words 'eco' and 'logia' B) Greek words 'oikos' and 'logos' C) French words 'ecologie' and 'system' D) German words 'okologie' and 'haus'

B) Greek words 'oikos' and 'logos'

Who first defined the term 'ecology' in 1866? A) Louis Pasteur B) Robert Koch C) Ernest Haeckel D) Sergei Winogradsky

C) Ernest Haeckel

When did the term 'microbial ecology' come into frequent use? A) Early 1920s B) Early 1940s C) Early 1960s D) Early 1980s

C) Early 1960s

What does a microbial population refer to? A) All microorganisms in an ecosystem B) A group of individual organisms of one species in a habitat C) Different species interacting together D) The total biomass of microbes

B) A group of individual organisms of one species in a habitat

What is the equation for an ecosystem? A) Ecosystem = Plants + Animals B) Ecosystem = Biotic community + Abiotic environment C) Ecosystem = Producers + Consumers D) Ecosystem = Habitat + Niche

B) Ecosystem = Biotic community + Abiotic environment

What is the correct order of biological organization from smallest to largest? A) Cell → Tissue → Organ → Organism → Population → Community → Ecosystem B) Molecule → Cell → Tissue → Population → Ecosystem C) Macromolecule → Cell → Organism → Population → Community → Ecosystem → Biosphere D) Organism → Community → Population → Ecosystem

C) Macromolecule → Cell → Organism → Population → Community → Ecosystem → Biosphere

What is the microbial equivalent of a single macroorganism? A) A bacterial cell B) A microcolony C) A population D) A biofilm

B) A microcolony

What does species richness measure? A) The proportion of each species B) The total number of different species present C) The biomass of all species D) The genetic diversity within species

B) The total number of different species present

What does species abundance refer to? A) Total number of species B) The proportion of each species in the community C) The diversity of phylotypes D) The richness of species

B) The proportion of each species in the community

Anoxic bacteria are characterized by: A) Requiring oxygen for growth B) Living in environments devoid of oxygen C) Producing oxygen through photosynthesis D) Being facultative anaerobes

B) Living in environments devoid of oxygen

What distinguishes anoxygenic bacteria from oxygenic phototrophs? A) They require oxygen B) They produce oxygen as a byproduct C) They perform photosynthesis without producing oxygen D) They cannot photosynthesize

C) They perform photosynthesis without producing oxygen

Obligate anaerobes are organisms that: A) Prefer oxygen but can survive without it B) Cannot survive in the presence of oxygen C) Produce oxygen D) Only live at high temperatures

B) Cannot survive in the presence of oxygen

What is a hyperthermophile? A) Organism with optimal growth at 40°C or higher B) Organism with optimal growth at 80°C or higher C) Organism with optimal growth at 15°C or lower D) Organism requiring high pressure

B) Organism with optimal growth at 80°C or higher

What are endoliths? A) Microbes living in extreme cold B) Organisms living inside rocks or in pores between mineral grains C) Microbes that produce methane D) Organisms requiring high salt concentrations

B) Organisms living inside rocks or in pores between mineral grains

Who is considered the father of taxonomy? A) Charles Darwin B) Carolus Linnaeus C) Ernst Haeckel D) Robert Whittaker

B) Carolus Linnaeus

Who first observed microorganisms using simple microscopes? A) Louis Pasteur B) Robert Koch C) Antonie van Leeuwenhoek D) Lazzaro Spallanzani

C) Antonie van Leeuwenhoek

Who is regarded as the founder of soil microbiology? A) Louis Pasteur B) Robert Koch C) Sergei Winogradsky D) Martinius Beijerinck

C) Sergei Winogradsky

What major contribution did Robert Koch make to microbiology? A) Discovered antibiotics B) Developed methods for pure culture isolation on solid media C) Discovered viruses D) Invented the microscope

B) Developed methods for pure culture isolation on solid media

The 'great oxidation event' refers to: A) Industrial pollution B) Oxygen production by cyanobacteria creating an aerobic atmosphere C) The discovery of oxygen D) Volcanic activity

B) Oxygen production by cyanobacteria creating an aerobic atmosphere

In binomial nomenclature

what does the first name represent? A) Species B) Genus C) Family D) Order

How many kingdoms are in Whittaker's classification system? A) Two B) Three C) Five D) Six

C) Five

What percentage similarity in 16S rRNA genes traditionally indicates the same species? A) 85% B) 90% C) 95% D) 97%

D) 97%

What is a strain in microbiology? A) A collection of different species B) A genetic variant or subtype within a species C) A different genus D) A viral classification

B) A genetic variant or subtype within a species

What are serovars? A) Strains that vary in morphology B) Strains that vary in antigenic properties C) Strains that vary in biochemical properties D) Different species

B) Strains that vary in antigenic properties

What percentage of Earth is covered by ocean? A) 50% B) 60% C) More than 70% D) 80%

C) More than 70%

Which physiological group is most abundant in wetland soil? A) Aerobic heterotrophic bacteria B) Anaerobic heterotrophic bacteria C) Nitrifying bacteria D) Denitrifying bacteria

B) Anaerobic heterotrophic bacteria

What is the fundamental niche? A) The actual niche occupied in nature B) The full range of conditions a microbe could use without competition C) The habitat of a microbe D) The food source of a microbe

B) The full range of conditions a microbe could use without competition

What is the realized niche? A) The potential niche in the lab B) The actual conditions/resources occupied considering competition C) The theoretical maximum niche D) The preferred temperature range

B) The actual conditions/resources occupied considering competition

What is a microbial guild? A) A group of closely related species B) Microorganisms from different taxa performing the same ecological function C) A taxonomic classification D) A type of bacterial colony

B) Microorganisms from different taxa performing the same ecological function

Which gene is used as a marker for ammonia-oxidizing bacteria? A) nifH B) amoA C) dsrAB D) mcrA

B) amoA

What is the primary function of methanogens? A) Nitrogen fixation B) Sulfate reduction C) Methane production from H₂ and CO₂ D) Ammonia oxidation

C) Methane production from H₂ and CO₂

Which gene is diagnostic for methanogenic archaea? A) amoA B) nirK C) mcrA D) nosZ

C) mcrA

What is the role of nitrifying bacteria? A) Convert N₂ to ammonia B) Convert ammonia to nitrite and nitrate C) Convert nitrate to N₂ D) Fix atmospheric nitrogen

B) Convert ammonia to nitrite and nitrate

What is the key enzyme in biological nitrogen fixation? A) Nitrogenase (nifH) B) Ammonia monooxygenase (amoA) C) Nitrite oxidoreductase (nxrB) D) Nitrous oxide reductase (nosZ)

A) Nitrogenase (nifH)

Anammox stands for: A) Anaerobic ammonia production B) Anaerobic ammonia oxidation C) Aerobic ammonia oxidation D) Anaerobic nitrate oxidation

B) Anaerobic ammonia oxidation

What is the equation for anammox? A) NH₄⁺ + O₂ → NO₂⁻ B) NH₄⁺ + NO₂⁻ → N₂ + 2H₂O C) NO₃⁻ → N₂ D) N₂ → NH₃

B) NH₄⁺ + NO₂⁻ → N₂ + 2H₂O

Which organisms perform symbiotic nitrogen fixation with legumes? A) Azotobacter B) Nitrosomonas C) Rhizobium and Bradyrhizobium D) Pseudomonas

C) Rhizobium and Bradyrhizobium

Denitrification converts: A) N₂ to NH₃ B) NH₃ to NO₂⁻ C) NO₃⁻ to N₂ D) NO₂⁻ to NO₃⁻

C) NO₃⁻ to N₂

Which gene is diagnostic for sulfate-reducing bacteria? A) amoA B) dsrAB C) mcrA D) nifH

B) dsrAB

Sulfate reducers convert: A) SO₄²⁻ to H₂S B) H₂S to SO₄²⁻ C) S⁰ to SO₄²⁻ D) HS⁻ to S⁰

A) SO₄²⁻ to H₂S

Aerobic methanotrophs use which gene for methane oxidation? A) mcrA B) pmoA C) amoA D) nirK

B) pmoA

Where is anaerobic methane oxidation (AOM) primarily found? A) Desert soils B) Marine sediments with sulfate C) Hot springs D) Acidic lakes

B) Marine sediments with sulfate

What is horizontal gene transfer (HGT)? A) Gene transfer from parent to offspring B) Gene transfer between unrelated organisms C) Mutation of genes D) Gene deletion

B) Gene transfer between unrelated organisms

Which mechanism of HGT involves uptake of free DNA? A) Conjugation B) Transduction C) Transformation D) Recombination

C) Transformation

What are plasmids? A) Viral genomes B) Extrachromosomal DNA elements C) Bacterial chromosomes D) RNA molecules

B) Extrachromosomal DNA elements

What is Average Nucleotide Identity (ANI) used for? A) Measuring gene expression B) Defining species boundaries (>95% = same species) C) Counting cells D) Identifying functional genes

B) Defining species boundaries (>95% = same species)

What is the 'great plate count anomaly'? A) Too many colonies on plates B) Culture methods recover <1% of cells seen microscopically C) Plates contaminated with fungi D) Difficulty counting colonies

B) Culture methods recover <1% of cells seen microscopically

What does metagenomics study? A) Single genomes B) Community genomes from environmental samples C) Only viral genomes D) Human genomes

B) Community genomes from environmental samples

What is the Shannon index used for? A) Measuring temperature B) Combining richness and evenness in diversity C) Counting cells D) Measuring pH

B) Combining richness and evenness in diversity

What is enrichment culture? A) Growing all microbes equally B) Tailoring conditions to favor microbes with particular metabolic abilities C) Adding nutrients randomly D) Sterilizing media

B) Tailoring conditions to favor microbes with particular metabolic abilities

What are acidophiles? A) Organisms growing best at high pH B) Organisms growing best at low (acidic) pH C) Organisms requiring high salt D) Organisms living at high temperature

B) Organisms growing best at low (acidic) pH

Halophiles require: A) High temperatures B) Low pH C) High salt concentrations D) High pressure

C) High salt concentrations

Psychrophiles have optimal growth at: A) 40°C or higher B) 15°C or lower C) 80°C or higher D) 25-37°C

B) 15°C or lower

What are piezophiles (barophiles)? A) Organisms living at high temperatures B) Organisms living optimally at high hydrostatic pressure C) Organisms requiring high oxygen D) Organisms living in acidic environments

B) Organisms living optimally at high hydrostatic pressure

What is interspecies hydrogen transfer? A) Exchange of genetic material B) H₂ consumption by one organism drives metabolism of another C) Competition for hydrogen D) Hydrogen production only

B) H₂ consumption by one organism drives metabolism of another

What is syntrophy? A) Competition between species B) Obligate cooperation where metabolism of one depends on another C) Parasitism D) Predation

B) Obligate cooperation where metabolism of one depends on another

What distinguishes viruses from cellular organisms? A) They have both DNA and RNA B) They contain only one type of nucleic acid (DNA or RNA) C) They have a nucleus D) They perform photosynthesis

B) They contain only one type of nucleic acid (DNA or RNA)

What are bacteriophages? A) Viruses that infect bacteria B) Bacteria that eat viruses C) Antibiotics D) Fungal spores

A) Viruses that infect bacteria

The typical size range of most viruses is: A) 1-5 µm B) 20-300 nm C) 500-1000 nm D) 5-10 µm

B) 20-300 nm

Early life forms were primarily: A) Aerobic phototrophs B) Anaerobes including methanogens and thermophiles C) Eukaryotes D) Multicellular organisms

B) Anaerobes including methanogens and thermophiles

The endosymbiont theory explains the origin of: A) Cell walls B) Mitochondria and chloroplasts C) Ribosomes D) DNA

B) Mitochondria and chloroplasts

When did the first eukaryotic organisms appear (approximately)? A) 0.5 Ga (billion years ago) B) 1.5 Ga C) 3.5 Ga D) 4.5 Ga

B) 1.5 Ga

What is a biofilm? A) A single bacterial cell B) A structured community of microbes embedded in EPS matrix C) A viral infection D) A type of culture medium

B) A structured community of microbes embedded in EPS matrix

What advantage do biofilms provide? A) Faster individual growth B) Protection from environmental stresses and antibiotics C) Reduced metabolic activity D) Decreased diversity

B) Protection from environmental stresses and antibiotics

Which domain includes organisms with ether-linked lipids in their membranes? A) Bacteria B) Eukarya C) Archaea D) All domains

C) Archaea

Which domain has 80S ribosomes? A) Bacteria B) Archaea C) Eukarya D) Bacteria and Archaea

C) Eukarya

Peptidoglycan containing muramic acid is found in: A) Archaea B) Eukarya C) Bacteria D) All three domains

C) Bacteria

What is bioremediation? A) Use of microbes to degrade pollutants B) Production of antibiotics C) Genetic engineering D) Vaccine development

A) Use of microbes to degrade pollutants

Enhanced Biological Phosphorus Removal (EBPR) relies on: A) Chemical precipitation B) Polyphosphate-accumulating organisms (PAOs) C) Filtration D) Chlorination

B) Polyphosphate-accumulating organisms (PAOs)

What does autecology study? A) Entire communities B) Particular organisms and their physiological ecology C) Only bacteria D) Abiotic factors only

B) Particular organisms and their physiological ecology

What does synecology study? A) Individual organisms B) Populations co-occurring in time and space C) Only viruses D) Laboratory cultures

B) Populations co-occurring in time and space

What are chemolithoautotrophs? A) Organisms using organic compounds for energy B) Organisms using inorganic compounds for energy and CO₂ as carbon source C) Organisms requiring light D) Heterotrophs

B) Organisms using inorganic compounds for energy and CO₂ as carbon source

Oxygenic photosynthesis is performed by: A) Purple sulfur bacteria B) Cyanobacteria and algae C) Methanogens D) Sulfate reducers

B) Cyanobacteria and algae

What is the role of decomposers? A) Primary production B) Breaking down organic matter to CO₂ or reduced products C) Nitrogen fixation only D) Methane oxidation only

B) Breaking down organic matter to CO₂ or reduced products

Which organisms are responsible for cellulose degradation? A) Methanogens B) Cellulomonas

Clostridium thermocellum

What are iron-oxidizing bacteria important for? A) Nitrogen fixation B) Acid mine drainage formation and iron cycling C) Methane production D) Photosynthesis

B) Acid mine drainage formation and iron cycling

Geobacter and Shewanella are known for: A) Nitrogen fixation B) Extracellular electron transfer and Fe(III) reduction C) Methane production D) Sulfate reduction

B) Extracellular electron transfer and Fe(III) reduction

What is functional redundancy in microbial ecology? A) One species performing one function B) Multiple species performing the same ecological function C) No overlap in functions D) Competition only

B) Multiple species performing the same ecological function

Alpha diversity refers to: A) Regional diversity B) Diversity within a single community C) Differences between communities D) Global diversity

B) Diversity within a single community

Beta diversity refers to: A) Diversity within a community B) Differences in community composition between environments C) Global diversity D) Genetic diversity

B) Differences in community composition between environments

What does high evenness in a community indicate? A) One species dominates B) All species have relatively equal abundances C) Low species richness D) High mutation rate

B) All species have relatively equal abundances

Rarefaction curves are used to: A) Measure temperature B) Plot observed richness versus sequencing depth C) Count colonies D) Measure pH

B) Plot observed richness versus sequencing depth

What is Stable Isotope Probing (SIP)? A) Measuring isotope ratios in rocks B) Tracking substrate assimilation to identify active microbial guilds C) Radioactive labeling D) DNA sequencing only

B) Tracking substrate assimilation to identify active microbial guilds

What did Beijerinck's principle state? A) Only bacteria exist B) 'Everything is everywhere

the environment selects' C) All microbes are pathogenic D) Pure cultures are unnecessary

Who developed the enrichment culture technique? A) Louis Pasteur B) Robert Koch C) Beijerinck and Winogradsky D) Antonie van Leeuwenhoek

C) Beijerinck and Winogradsky

The Winogradsky column demonstrates: A) Pure culture techniques B) Vertical stratification of microbial guilds based on redox and light C) Antibiotic production D) Virus replication

B) Vertical stratification of microbial guilds based on redox and light

What is metatranscriptomics? A) Study of community DNA B) Study of expressed genes (mRNA) in communities C) Study of proteins D) Study of metabolites

B) Study of expressed genes (mRNA) in communities

Which phylum includes the 'Low G+C' Gram-positive bacteria? A) Actinobacteria B) Proteobacteria C) Firmicutes D) Chlamydiae

C) Firmicutes

The genus Streptomyces belongs to which phylum? A) Firmicutes B) Actinobacteria C) Proteobacteria D) Bacteroidetes

B) Actinobacteria

What is the primary carbon source for autotrophs? A) Glucose B) Acetate C) CO₂ D) Methane

C) CO₂

Which organisms are capable of lignin degradation? A) Most bacteria B) White-rot and brown-rot fungi C) Methanogens D) Nitrifiers

B) White-rot and brown-rot fungi

What is the role of Nitrobacter in the nitrogen cycle? A) Ammonia oxidation B) Nitrite oxidation to nitrate C) Nitrogen fixation D) Denitrification

B) Nitrite oxidation to nitrate

Mercury methylation in sediments is performed by: A) Cyanobacteria B) Desulfovibrio species C) Nitrifiers D) Methanogens

B) Desulfovibrio species

What is the main electron donor for hydrogenotrophic methanogens? A) Acetate B) Methanol C) H₂ D) Glucose

C) H₂

Beggiatoa forms conspicuous mats at: A) Desert surfaces B) Oxic-anoxic interfaces where H₂S and O₂ meet C) Deep sea vents only D) Acidic hot springs

B) Oxic-anoxic interfaces where H₂S and O₂ meet

What are ANME archaea involved in? A) Aerobic methane oxidation B) Anaerobic methane oxidation coupled to sulfate reduction C) Methane production D) Nitrogen fixation

B) Anaerobic methane oxidation coupled to sulfate reduction

The nosZ gene encodes: A) Ammonia monooxygenase B) Nitrous oxide reductase C) Nitrogenase D) Methane monooxygenase

B) Nitrous oxide reductase

What is the significance of the 'microbial dark matter'? A) Microbes that are black in color B) Uncultured microbial lineages detectable only by molecular methods C) Microbes living in caves D) Extinct microorganisms

B) Uncultured microbial lineages detectable only by molecular methods

Transduction in bacteria involves: A) Direct cell-to-cell contact B) Phage-mediated DNA transfer C) Uptake of free DNA D) Spontaneous mutation

B) Phage-mediated DNA transfer

What is the main limitation of culture-dependent methods in microbial ecology? A) Too expensive B) Too slow C) Recover <1% of actual microbial diversity D) Require too much equipment

C) Recover <1% of actual microbial diversity