Introduction
Microbial and Molecular Ecology explores how microorganisms interact with one another, their environment, and the genetic mechanisms that drive those interactions.
It combines ecology, genetics, and molecular biology to explain microbial diversity, gene flow, biofilm formation, and the role of microbes in nutrient cycling, climate regulation, and biotechnology.
This quiz is ideal for students of Environmental Science, Microbiology, Biotechnology, and Ecology preparing for exams such as UGC NET, GATE, CSIR-JRF, and university entrance tests.
Microbial and Molecular Ecology MCQs
- Microbial ecology studies
a) Microbe–microbe interactions only
b) Microorganisms in relation to their environment
c) Plant physiology
d) Industrial fermentation - The father of microbial ecology is
a) Louis Pasteur
b) Sergei Winogradsky
c) Robert Koch
d) Anton van Leeuwenhoek - The Winogradsky column demonstrates
a) Microbial diversity in stratified environments
b) Antibiotic resistance
c) Nitrogen fixation only
d) Pathogen growth - The term microbiome refers to
a) All bacteria in the soil
b) The collective genomes of microorganisms in a habitat
c) Only gut microbes
d) Viruses only - The 16S rRNA gene is widely used for
a) Protein synthesis
b) Phylogenetic identification of bacteria
c) Antibiotic production
d) Mutation detection - Metagenomics allows scientists to
a) Culture all microbes in a lab
b) Sequence genetic material directly from the environment
c) Study only viruses
d) Remove pollutants - The nitrogen-fixing symbiont of legumes is
a) Rhizobium
b) Nitrosomonas
c) Clostridium
d) Azotobacter - Nitrification involves conversion of
a) NH₃ → NO₂⁻ → NO₃⁻
b) NO₃⁻ → N₂
c) N₂ → NH₃
d) NO₂⁻ → NH₃ - Denitrification is carried out by
a) Nitrobacter
b) Pseudomonas and Paracoccus
c) Rhizobium
d) Azospirillum - The carbon cycle in microbial ecology involves
a) Photosynthesis and respiration
b) DNA replication
c) Methane oxidation only
d) Antibiotic resistance - Methanogens belong to
a) Archaea
b) Bacteria
c) Fungi
d) Algae - The PCR (Polymerase Chain Reaction) technique is essential for
a) Amplifying DNA fragments
b) Synthesizing proteins
c) Digesting RNA
d) Sequencing proteins - Horizontal gene transfer refers to
a) Parent-to-offspring transfer
b) Gene movement between unrelated organisms
c) Mutation accumulation
d) Gene deletion - Transformation, transduction, and conjugation are examples of
a) Gene silencing
b) Horizontal gene transfer mechanisms
c) Replication modes
d) DNA repair - Quorum sensing enables microbes to
a) Detect toxins
b) Communicate via signaling molecules to coordinate behavior
c) Produce energy
d) Digest nutrients faster - The Lux operon in Vibrio fischeri controls
a) Bioluminescence
b) Antibiotic synthesis
c) Biofilm formation
d) Metal resistance - Biofilms are
a) Free-floating microbes
b) Microbial communities embedded in extracellular polymeric substances
c) Dead cell layers
d) Viruses on surfaces - The first step in biofilm formation is
a) Detachment
b) Surface attachment
c) Maturation
d) Signal quorum - The hydrogenosome is a microbial organelle found in
a) Aerobic bacteria
b) Anaerobic protozoa
c) Cyanobacteria
d) Fungi only - Functional genes in metagenomics represent
a) Genes coding for ecological or metabolic traits
b) Junk DNA
c) Only ribosomal RNA
d) Viral fragments - DGGE (Denaturing Gradient Gel Electrophoresis) is used for
a) Protein purification
b) DNA fingerprinting of microbial communities
c) Lipid separation
d) RNA degradation - FISH (Fluorescence In Situ Hybridization) identifies microbes by
a) Culturing them
b) Using fluorescently labeled DNA probes
c) Using Gram staining
d) Immunoassay - Amplicon sequencing targets
a) Specific conserved genes such as 16S rRNA
b) Whole genome
c) Protein sequences
d) None of these - Microbial mats are
a) Multilayered microbial communities in aquatic habitats
b) Mineral deposits
c) Plant residues
d) Insect colonies - The soil microbial biomass carbon (SMBC) is an indicator of
a) Soil fertility and microbial activity
b) Carbonate concentration
c) Mineral hardness
d) Soil texture - Microbial loop in aquatic ecosystems describes
a) Microbial recycling of organic matter to higher trophic levels
b) Food chain among vertebrates
c) Sedimentation process
d) Nutrient precipitation - Plasmids in bacteria often carry
a) Ribosomal genes
b) Accessory genes such as antibiotic resistance
c) Chromosomal DNA
d) Histone proteins - Operon concept was proposed by
a) Jacob and Monod
b) Darwin
c) Avery and MacLeod
d) Watson and Crick - In the lac operon, lactose acts as
a) Repressor
b) Inducer
c) Co-repressor
d) None - Environmental genomics focuses on
a) Organismal morphology
b) Gene function in environmental samples
c) Protein folding
d) Pathology - CRISPR–Cas systems in bacteria serve as
a) Adaptive immune defense against phages
b) Protein synthesis machinery
c) RNA processing tool
d) Lipid metabolism - Archaea differ from bacteria by
a) Cell wall lacking peptidoglycan
b) Having nuclei
c) Chlorophyll presence
d) DNA in membrane-bound organelles - Extremophiles thrive in
a) Moderate environments
b) Extreme temperature, pH, or salinity
c) Shaded forests only
d) None - The first microbial genome sequenced was of
a) Haemophilus influenzae
b) E. coli
c) Bacillus subtilis
d) Mycobacterium tuberculosis - Siderophores are produced by microbes to
a) Capture iron from the environment
b) Absorb nitrogen
c) Fix phosphorus
d) Produce antibiotics - Symbiosis between fungi and algae in lichens is
a) Parasitic
b) Mutualistic
c) Commensal
d) Competitive - The human gut microbiota plays a crucial role in
a) Vitamin synthesis and metabolism
b) DNA replication
c) Hearing
d) Reflex actions - Antibiotic resistance genes (ARGs) in the environment are spread mainly by
a) Horizontal gene transfer
b) Vertical inheritance only
c) Photosynthesis
d) Mutation alone - Phage therapy uses
a) Viruses to treat bacterial infections
b) Antibiotics
c) Fungi
d) Hormones - Metatranscriptomics studies
a) DNA sequences
b) Actively expressed genes (RNA) in microbial communities
c) Proteins
d) Lipids - The human microbiome project was launched by
a) WHO
b) NIH (USA)
c) UNESCO
d) CSIR India - Chemoautotrophic bacteria obtain energy from
a) Oxidation of inorganic compounds
b) Light
c) Organic matter
d) Heat only - Microbial succession in decomposing material occurs due to
a) Changing environmental conditions
b) Mutation
c) Parasitism
d) None - Phytoremediation is often assisted by
a) Rhizosphere microbes
b) Fungi only
c) Protozoa
d) Insects - Molecular ecology differs from classical ecology by
a) Using molecular tools to study ecological processes
b) Focusing on morphology
c) Ignoring genes
d) Being unrelated to genetics - Ribotyping is used for
a) Microbial strain identification based on rRNA genes
b) Protein profiling
c) Cell counting
d) Toxin detection - Ecotypes within microbes indicate
a) Genetically distinct populations adapted to specific niches
b) Nutrient types
c) Pollution types
d) Energy levels - Proteomics in microbial ecology helps study
a) Functional proteins expressed under different environmental conditions
b) RNA structures
c) DNA mutations only
d) None - Metaproteomics combines
a) Protein analysis of whole microbial communities
b) DNA fingerprinting
c) Metabolite separation
d) None - Stable-isotope probing (SIP) links
a) Metabolic activity with specific microbial taxa using labeled substrates
b) pH measurement
c) Temperature gradients
d) Mineral deposition
Answers and Explanations
| No. | Answer | Explanation |
|---|---|---|
| 1 | b | Focuses on microbes and their environment. |
| 2 | b | Winogradsky pioneered microbial ecology. |
| 3 | a | Shows layered microbial metabolism. |
| 4 | b | Genome collection of all microbes in a niche. |
| 5 | b | 16S rRNA used in bacterial phylogeny. |
| 6 | b | Environmental DNA sequencing method. |
| 7 | a | Rhizobium forms root nodules. |
| 8 | a | Key steps of nitrification. |
| 9 | b | Pseudomonas and Paracoccus denitrify. |
| 10 | a | Driven by photosynthesis + respiration. |
| 11 | a | Methanogens belong to Archaea. |
| 12 | a | PCR amplifies DNA. |
| 13 | b | Genes move between species. |
| 14 | b | Three HGT modes. |
| 15 | b | Cell-to-cell communication. |
| 16 | a | Controls luminescence. |
| 17 | b | EPS-embedded microbial consortium. |
| 18 | b | Attachment is the first step. |
| 19 | b | Anaerobic protozoa organelle. |
| 20 | a | Functional gene = metabolic role. |
| 21 | b | Used to profile community DNA. |
| 22 | b | Fluorescent probe hybridization. |
| 23 | a | Targets 16S or 18S genes. |
| 24 | a | Layered phototrophic structures. |
| 25 | a | Indicates soil microbial health. |
| 26 | a | Transfers organic C back to higher trophic levels. |
| 27 | b | Extra-chromosomal DNA. |
| 28 | a | Jacob & Monod proposed operon model. |
| 29 | b | Lactose induces lac operon. |
| 30 | b | Studies gene function in nature. |
| 31 | a | Defense vs. phage infection. |
| 32 | a | No peptidoglycan; unique lipids. |
| 33 | b | Adapted to extreme conditions. |
| 34 | a | First complete genome sequenced (1995). |
| 35 | a | Iron-binding compounds. |
| 36 | b | Mutualistic association. |
| 37 | a | Gut microbes aid metabolism. |
| 38 | a | ARGs spread via HGT. |
| 39 | a | Bacteriophages as therapy. |
| 40 | b | RNA-based expression profiling. |
| 41 | b | NIH initiative (2007). |
| 42 | a | Energy from oxidation of NH₃, H₂S etc. |
| 43 | a | Due to succession of conditions. |
| 44 | a | Root microbes enhance remediation. |
| 45 | a | Integrates molecular tools with ecology. |
| 46 | a | rRNA-based fingerprinting. |
| 47 | a | Genetic variants adapted locally. |
| 48 | a | Analyzes protein functions. |
| 49 | a | Community-level proteomic study. |
| 50 | a | Uses ¹³C or ¹⁵N labels to trace activity. |
Decoding Biosphere 