Module Flashcards
What is the Anthropocene, and why is it significant?
The Anthropocene is an unofficial geologic time period that marks when human activity began significantly affecting Earth’s climate and ecosystems. It is significant because it highlights how human actions are breaching planetary boundaries, causing fundamental shifts in Earth systems.
What are the key impacts of the Anthropocene?
Key impacts include:
Climate change.
Resource extraction.
Biodiversity loss.
Land use changes.
Waste production.
These changes are leaving a distinct geological record and altering planetary processes.
What are planetary boundaries, and why are they important?
Planetary boundaries are limits within which humanity can safely operate to avoid destabilizing Earth’s systems. Exceeding these boundaries, such as for climate change or biodiversity, risks causing irreversible environmental damage.
How do perspectives on the Anthropocene vary?
- Geological perspective: Focuses on human impact leaving a stratigraphic record.
- Biosphere perspective: Highlights biodiversity loss and biogeochemical cycles.
- Cultural perspective: Examines the Anthropocene’s influence on art, architecture, and critiques of capitalism and environmental justice.
What is “The Great Acceleration,” and how does it relate to the Anthropocene?
The Great Acceleration refers to the rapid increase in human impacts on Earth systems, particularly since the mid-20th century. It includes trends like increased CO2 emissions, deforestation, and population growth, and is often considered the defining period of the Anthropocene.
What are the arguments for and against formalizing the Anthropocene as a geologic epoch?
For:
Robust evidence of human impact (e.g., CO2 levels, fly ash particles).
Distinct stratigraphic markers.
Against:
Too recent to qualify geologically.
Seen as a political statement rather than a scientific necessity.
How can the Anthropocene motivate sustainability?
The Anthropocene underscores the unprecedented scale of human influence, urging efforts to:
Work within planetary boundaries.
Promote interdisciplinary solutions involving science, economics, and humanities.
Develop sustainable practices to mitigate environmental harm.
What is natural capital, and why is it important?
Natural capital refers to the world’s stocks of natural assets, including soil, air, water, and living organisms, which provide ecosystem goods and services essential for human life, such as clean water, food, and climate regulation.
What are ecosystem goods and services, and how are they categorized?
Ecosystem goods and services are benefits humans derive from ecosystems, divided into:
Supporting: Soil formation, nutrient cycling.
Regulating: Climate and water quality.
Provisioning: Food, water, and medicines.
Cultural: Recreational and spiritual value.
What is a biome, and what factors determine its type?
A biome is a major ecological community defined by its vegetation and adapted organisms. Biomes are determined by precipitation, air temperature, and soil characteristics.
What are the five major types of biomes, and what ecosystem services do they provide?
Aquatic: Water filtration, climate regulation.
Grassland: Soil formation, grazing land.
Forest: Carbon sequestration, timber, biodiversity.
Desert: Mineral resources, habitat for adapted species.
Tundra: Carbon storage, cultural value.
How does agriculture impact natural ecosystems and biodiversity?
Agriculture converts natural ecosystems into agroecosystems, leading to:
Biodiversity loss.
Habitat destruction.
Altered nutrient cycles and soil erosion.
Water overuse and pollution.
What is deforestation, and why is it a concern?
Deforestation is the clearing of forests for agriculture or other uses, reducing biodiversity, disrupting water and soil quality, and releasing carbon dioxide, contributing to climate change.
How does soil health contribute to ecosystem services?
Healthy soil is biologically active and stable, supporting plant growth, nutrient cycling, and water filtration. Poor soil health from improper use can lead to reduced fertility and environmental damage.
What is desertification, and what causes it?
Desertification is the persistent reduction of ecosystems’ capacity to provide services, caused by factors such as overgrazing, deforestation, improper water use, and climate change.
What is ecological scale, and why is it important in environmental studies?
Ecological scale refers to the spatial and temporal dimensions at which ecological processes are studied. It is crucial because processes may vary with scale, affecting how results are interpreted.
How does the Millennium Ecosystem Assessment contribute to our understanding of ecosystems?
The Millennium Ecosystem Assessment evaluates the current state of ecosystems and their services, highlighting their value to human well-being and the impacts of human activities.
What is natural capital?
Natural capital refers to the world’s stocks of natural assets, including geology, soil, air, water, and living organisms, which provide goods and services essential for human life.
Define ecosystem goods and services.
Ecosystem goods and services are the benefits humans derive from ecosystems, such as clean air, water, food, and climate regulation.
Name the four types of ecosystem services provided by forests.
The four types are:
Supporting (e.g., nutrient cycling, photosynthesis)
Provisioning (e.g., timber, wild food)
Regulating (e.g., temperature regulation, carbon sequestration)
Cultural (e.g., recreation, inspiration).
What is an ecosystem?
An ecosystem is a community of plants, animals, and micro-organisms interacting with their physical environment as a unit.
What are biomes, and what are the two main factors defining them?
Biomes are major ecological communities characterized by dominant vegetation and organism adaptations. They are primarily defined by precipitation and air temperature.
List the five major types of biomes.
The five major types are:
Aquatic
Grassland
Forest
Desert
Tundra
How does agriculture impact global biodiversity?
Agriculture affects biodiversity through habitat conversion, loss of wild species, changes in species composition, offsite impacts, and loss of genetic diversity within crops.
What percentage of the Earth’s surface is covered by cultivated systems?
Cultivated systems cover approximately 24% of the Earth’s surface.
How do forests influence rainfall patterns?
Forests regulate rainfall by acting as sponges that soak up and store water, helping to even out annual waterflows and reduce erosion.
What is desertification, and what causes it?
Desertification is the persistent reduction in an ecosystem’s capacity to supply services, caused by factors such as deforestation, overgrazing, poor land management, and climate-related processes.
What is soil health, and what factors contribute to healthy soil?
Healthy soil is physically, nutritionally, and biologically balanced, stable, and productive. It depends on balanced biological activity, proper land use, and minimal environmental disturbance.
How does deforestation contribute to climate change?
Deforestation releases stored carbon dioxide and other greenhouse gases into the atmosphere, contributing to global warming.
What is the significance of scale in ecological studies?
Scale affects how ecological studies are conducted, interpreted, and understood. Patterns apparent at one scale may not be evident at another, influencing perceptions of ecological processes.
What are the consequences of large-scale forest clearing?
Consequences include altered rainfall patterns, decreased rainfall, increased soil erosion, and loss of biodiversity.
Why are monocultures less biodiverse than natural ecosystems?
Monocultures focus on a single crop, reducing plant diversity and impacting other species, as weeds and competing plants are often removed.
What is biodiversity?
Biodiversity is the variety of life, including plants, animals, and micro-organisms, the genetic variation within species, and the ecosystems they form.
How many species have been described, and what is the estimated total?
Over 2 million species have been described, but estimates suggest there may be 5-15 million species.
What are megadiverse countries?
Megadiverse countries are the 17 most biodiversity-rich nations, accounting for at least two-thirds of non-fish vertebrate species and three-quarters of higher plant species.
Define a species.
A species is a group of organisms that naturally reproduce to create fertile offspring, although exceptions like hybrids and asexual organisms exist.
What is natural selection?
Natural selection is the process where organisms with advantageous traits are more likely to survive and reproduce, passing these traits to the next generation.
What is speciation?
Speciation occurs when a group within a species becomes isolated and develops unique characteristics, forming a new species.
Name some benefits of biodiversity for humans.
Benefits include pollination, agricultural products, medicine (e.g., aspirin and penicillin), and cultural services like recreation and inspiration.
What causes changes in biodiversity?
Changes are caused by habitat destruction, invasive species, pollution, climate change, and habitat fragmentation.
What are the effects of habitat fragmentation?
Habitat fragmentation leads to isolated populations, increased genetic drift, inbreeding, and higher extinction risks for small populations.
How does climate change impact biodiversity?
Climate change affects species’ distributions, phenology (timing of life events like flowering), and reduces their capacity to adapt due to natural barriers.
What is biodiversity offsetting?
Biodiversity offsetting involves conservation activities designed to compensate for ecological losses caused by development.
What is rewilding?
Rewilding reinstates natural processes, such as grazing and predation, and may involve reintroducing species to restore healthy ecosystems.
Give an example of ecosystem restoration.
Coral nurseries involve hanging damaged coral fragments on PVC pipes for rejuvenation before transplanting them into damaged reefs.
What are some threats from invasive species?
Invasive species can disrupt ecosystems by preying on native species, outcompeting them for resources, or altering habitats, such as the jellyfish-like ctenophore in the Black Sea.
Why is biodiversity important for agriculture?
Biodiversity supports agriculture by providing genetic resources, pollinators, natural pest control, and diverse crops for food and biofuels.
What is ecology?
Ecology is the scientific study of the distribution and abundance of organisms and their interactions with each other and the environment.
Why is the study of ecology important?
Understanding ecology helps in conserving biodiversity, managing natural resources sustainably, predicting climate change effects, and developing nature-based solutions to environmental problems.
What are the key components of an ecosystem?
An ecosystem consists of a biological community (all interacting species) and the abiotic environment (non-living factors like water, soil, and climate).
What are the two main types of species interactions discussed in this lecture?
Competition (organisms competing for resources) and predation (one organism consuming another).
What is the difference between intraspecific and interspecific competition?
Intraspecific competition occurs within the same species.
Interspecific competition occurs between different species with similar ecological requirements.
What is density-dependent population regulation?
As population density increases, competition for resources intensifies, leading to lower survival and reproductive rates, which regulates population size.
What are the two mechanisms by which competition occurs?
Interference competition: Direct interactions, such as aggression or territorial behaviour, preventing others from accessing resources.
Exploitation competition: Indirect interaction where individuals consume resources, leaving less for others.
How does predation differ from competition?
Predation involves one organism (the predator) consuming another (the prey), whereas competition involves organisms vying for the same resources without direct consumption of one another.
What are the three functional categories of predators?
True predators: Kill prey immediately and consume multiple prey in a lifetime.
Grazers: Consume parts of multiple prey without usually killing them.
Parasites: Consume only part of their host and often have a long-term association.
What is apparent competition?
When two prey species share a common predator, an increase in one prey population may lead to an increase in predator numbers, negatively impacting both prey populations.
How did cougar predation affect bighorn sheep in the Sierra Nevada?
Bighorn sheep suffered higher mortality in areas where their range overlapped with mule deer, as cougars primarily preyed on mule deer but also killed sheep.
What are invasive species, and why are they problematic?
Invasive species are non-native organisms that establish in new areas, often outcompeting native species, causing environmental and economic damage.
Give an example of an invasive species that caused significant ecological disruption.
The Burmese python in Florida’s Everglades has drastically reduced populations of native mammals like raccoons and deer by predation.
How did pine martens impact grey and red squirrel populations in Ireland?
Pine martens, a native predator, caused a decline in invasive grey squirrels while allowing native red squirrels to recover.
What is classical biological control, and how has it been used effectively?
Classical biological control involves introducing natural enemies to control invasive species, such as the vedalia beetle used to control cottony cushion scale in California.
What is ecology?
Ecology is the scientific study of the distribution and abundance of organisms and their interactions with each other and the environment.
Why is the study of ecology important?
It helps in conserving biodiversity, managing natural resources sustainably, predicting climate change effects, and developing nature-based solutions to environmental problems.
What are the key components of an ecosystem?
An ecosystem consists of a biological community (all interacting species) and the abiotic environment (non-living factors like water, soil, and climate).
What are the two main types of species interactions discussed in this lecture?
Competition (organisms competing for resources) and predation (one organism consuming another).
What is the difference between intraspecific and interspecific competition?
Intraspecific competition occurs within the same species.
Interspecific competition occurs between different species with similar ecological requirements.
What is density-dependent population regulation?
As population density increases, competition for resources intensifies, leading to lower survival and reproductive rates, which regulates population size.
What are the two mechanisms by which competition occurs?
Interference competition: Direct interactions, such as aggression or territorial behaviour, preventing others from accessing resources.
Exploitation competition: Indirect interaction where individuals consume resources, leaving less for others.
How does predation differ from competition?
Predation involves one organism (the predator) consuming another (the prey), whereas competition involves organisms vying for the same resources without direct consumption of one another.
What are the three functional categories of predators?
True predators: Kill prey immediately and consume multiple prey in a lifetime.
Grazers: Consume parts of multiple prey without usually killing them.
Parasites: Consume only part of their host and often have a long-term association.
What is apparent competition?
When two prey species share a common predator, an increase in one prey population may lead to an increase in predator numbers, negatively impacting both prey populations.
How did cougar predation affect bighorn sheep in the Sierra Nevada?
Bighorn sheep suffered higher mortality in areas where their range overlapped with mule deer, as cougars primarily preyed on mule deer but also killed sheep.
What are invasive species, and why are they problematic?
Invasive species are non-native organisms that establish in new areas, often outcompeting native species, causing environmental and economic damage.
Give an example of an invasive species that caused significant ecological disruption.
The Burmese python in Florida’s Everglades has drastically reduced populations of native mammals like raccoons and deer by predation.
How did pine martens impact grey and red squirrel populations in Ireland?
Pine martens, a native predator, caused a decline in invasive grey squirrels while allowing native red squirrels to recover.
What is classical biological control, and how has it been used effectively?
Classical biological control involves introducing natural enemies to control invasive species, such as the vedalia beetle used to control cottony cushion scale in California.
What are the two ecological interactions that affect population size over time?
Competition (when resources are limited) and Predation (when one organism consumes another for food).
What is the difference between population growth in uncrowded and crowded environments?
Uncrowded environments: Exponential growth occurs when births exceed deaths (e.g., whooping cranes).
Crowded environments: Growth follows an S-shaped logistic curve due to intraspecific competition.
How do predator-prey dynamics influence population size?
Predators regulate prey populations, and prey abundance affects predator numbers, leading to coupled oscillations (e.g., wolves and moose on Isle Royale, Michigan).
What factors, other than competition and predation, influence population dynamics?
Disturbance events (e.g., extreme weather).
Chance variation in birth and death rates.
Environmental changes and genetic drift.
Catastrophic events (e.g., disease outbreaks).
What is Minimum Viable Population (MVP)?
The smallest population size required for a species to survive long-term (99% chance of survival for 1,000 years).
Why is genetic diversity important in conservation?
Low genetic diversity makes species vulnerable to diseases, environmental changes, and inbreeding depression.
How do scientists determine the Minimum Dynamic Area (MDA) needed to sustain a population?
By estimating:
Carrying capacity (how many individuals the habitat can support).
Home range size of individuals or social groups.
Habitat quality and resource availability.
Why are large carnivores particularly vulnerable to extinction?
They require large habitats; for example, a viable grizzly bear population (1,000 individuals) needs 2 million km².
What is a metapopulation?
A collection of subpopulations in different habitat patches, linked by migration and dispersal.
Why is migration important for metapopulation survival?
It allows recolonization of empty habitat patches and prevents local extinctions.
How does habitat fragmentation threaten species like the Iberian lynx?
The lynx is limited to isolated subpopulations with little genetic exchange, increasing extinction risk.
What is an example of a successful wildlife corridor?
Banff National Park, Canada, has wildlife bridges over highways, maintaining genetic diversity in black bears and grizzly bears.
What is a keystone species, and why is it important?
A species that has a disproportionate impact on community structure; removing it causes cascading effects (e.g., wolves in Yellowstone).
What is ecological succession?
The process by which communities change over time, either through primary succession (on new land) or secondary succession (after disturbance).
How did wolf reintroduction in Yellowstone affect the ecosystem?
Wolves controlled elk populations, allowing tree growth, which increased beaver numbers and habitat diversity.
What is systems ecology?
Systems ecology studies the flow of energy, nutrient cycling, and interactions within ecosystems to understand the structure and function of Earth’s life systems.
What are the two main types of resources organisms need to survive?
Biotic resources (e.g., food, nutrients) and abiotic resources (e.g., sunlight, water, space).
How do conditions differ from resources in ecology?
Conditions (e.g., temperature, humidity, salinity) affect organisms but are not consumed, whereas resources are actively used and depleted.
What is trophic dynamics?
The movement of energy through different levels of a food web, from primary producers to decomposers.
What is the primary energy source for most ecosystems?
Sunlight, used by photoautotrophs in photosynthesis to produce organic matter.
What is gross primary productivity (GPP), and how is it different from net primary productivity (NPP)?
GPP: Total energy captured by photosynthesis.
NPP: Energy left for growth and reproduction after respiration (NPP = GPP - R).
Why do coastal waters have higher primary productivity than open oceans?
They receive more nutrients from river inputs and have wave action that mixes nutrients into surface waters.
What limits secondary production in ecosystems?
The availability of primary production (energy from plants), which determines how much energy moves up the food chain.
What happens to energy as it moves up trophic levels?
Much is lost as heat and waste, leading to lower energy efficiency at higher trophic levels.
Why do endotherms (warm-blooded animals) have lower production efficiency than ectotherms?
They use more energy for metabolism (maintaining body temperature), leaving less for growth and reproduction.
What are the two major food chains in ecosystems?
Grazing food chain (energy from living plants).
Detrital food chain (energy from dead organic matter, decomposers).
Why are decomposers crucial for ecosystems?
They recycle nutrients, breaking down organic matter into forms usable by primary producers.
What factors affect the rate of decomposition?
Quality of organic matter (e.g., lignin-rich materials decompose slowly).
Environmental conditions (e.g., temperature, soil moisture, pH).
What is Human Appropriation of Net Primary Productivity (HANPP)?
The fraction of global NPP humans use for food, fuel, and land conversion, reducing energy available for natural ecosystems.
What strategies can reduce human impact on ecosystems?
Reducing per capita NPP consumption.
Sustainable agriculture (agroecology, agroforestry).
Protecting and connecting natural habitats.
What is the hydrological cycle?
The continuous movement of water between the atmosphere, land, and oceans through processes like evaporation, precipitation, and runoff.
What are the main states of water in the hydrological cycle?
Precipitation (rain, snow, sleet)
Ice/Snow (solid state)
Condensation (formation of clouds)
Water vapor (gaseous state in the atmosphere)
What are the key water transport processes in the cycle?
Runoff (movement of water on land)
Transpiration (release of water from plants)
Evaporation (liquid water turning into vapor)
Infiltration (water seeping into the ground)
What is the water balance equation used for?
It quantifies the flow of water in and out of a system:
𝑃+𝑄in=𝐸𝑇+Δ𝑆+𝑄out
P+Q in =ET+ΔS+Qout
P = Precipitation
Qin = Water flow into an area
ET = Evapotranspiration
ΔS = Change in water storage
Qout = Water flow out of an area
What is a hydrograph, and what does it show?
A hydrograph visualizes river discharge over time in response to rainfall, showing peak rainfall, peak discharge, lag time, and flow variations.
What factors influence the shape of a hydrograph?
Soil type (permeability affects infiltration rates)
Land use (urban areas increase runoff)
Rainfall intensity (heavy rainfall causes flash floods)
Vegetation cover (more plants slow down runoff)
Why are mountains important in the hydrological cycle?
They generate orographic precipitation (rain increases with altitude).
They store snow and ice, providing long-term water sources for rivers.
They supply freshwater to millions of people (e.g., Himalayas, Andes).
How does glacial meltwater contribute to water supply?
In Chile, meltwater supports agriculture and 10 million people.
In China and India, hundreds of millions rely on Himalayan meltwater.
How does temperature increase affect rainfall?
Warmer air holds 7% more water per °C.
Increases evaporation, leading to more extreme rainfall and droughts.
Strengthens climate variability, increasing flooding and dry spells.
What are the climate change predictions for freshwater systems?
Global temperatures will exceed 1.5°C by 2041–2060.
Freshwater ecosystems will be more sensitive to warming.
Water quality will decrease due to changes in temperature and oxygen levels.
How is surface runoff expected to change by 2050?
Increases at high latitudes and wet tropics.
Decreases in dry tropical regions.
Streamflow changes will affect agriculture, water supply, and ecosystems.
What are the consequences of glacial retreat on water availability?
Initially, runoff increases due to melting.
In the long term, water storage decreases, leading to reduced river flows.
How does climate change affect flooding and droughts?
More intense rainfall leads to urban and flash floods.
Increased droughts in dry regions (e.g., Australia, California, South Africa).
Snow-fed river basins experience earlier peak flows and summer droughts.
How does human activity worsen water shortages?
Irrigation uses 90% of global water consumption, reducing supply.
Deforestation and land use changes disrupt groundwater recharge.
Urbanization increases runoff pollution and reduces infiltration.
What are potential solutions to water scarcity?
Efficient irrigation to reduce freshwater overuse.
Conservation of wetlands to store and purify water.
Reducing per capita water consumption in industrialized countries.
What is environmental microbiology?
The study of microorganisms in natural and artificial environments, including their roles in ecosystems and their impact on environmental health.
What are the main objectives of environmental microbiology?
Describe microbial diversity and abundance in different environments.
Explain microbial roles in biogeochemical cycles (carbon, nitrogen).
Assess how microbes interact with soil, water, and plants.
Evaluate their beneficial and harmful effects on environmental quality.
Who first discovered microorganisms and when?
Antonie van Leeuwenhoek (1676) using the first microscope, calling them “animalcules.”
What was Louis Pasteur’s contribution to microbiology?
He disproved spontaneous generation and demonstrated that microbes exist in the air.
What are Koch’s postulates, and why are they important?
A set of criteria to link specific microorganisms to diseases, which also helped establish the pure culture technique.
What is the Great Plate Count Anomaly?
A discrepancy where only ~1% of microbes are culturable, while microscopic and molecular methods reveal much higher diversity.
What are the six major microbial groups in the environment?
Bacteria, Archaea, Fungi, Algae, Protozoa, and Viruses.
What are the key differences between prokaryotes and eukaryotes?
Prokaryotes: No nucleus, no membrane-bound organelles, smaller (e.g., Bacteria, Archaea).
Eukaryotes: Have a nucleus, complex internal structures, larger (e.g., Fungi, Algae, Protozoa).
Why are Archaea important in environmental microbiology?
They thrive in extreme environments and play roles in methane production and nitrification.
How do microorganisms benefit coral reefs?
Zooxanthellae (symbiotic algae) provide 90% of coral energy.
Bacteria and Archaea help with nitrogen fixation and nutrient cycling.
Some microbes produce antimicrobial compounds to protect corals.
What are the key questions addressed in microbial community analysis?
Who is there? (Taxonomic composition)
How many? (Abundance of microorganisms)
What are they doing? (Functional roles and metabolic activity)
Why are microbial communities important?
Microorganisms:
Were the first life forms and shaped Earth’s chemistry
Are at the base of the food web
Recycle organic matter and degrade pollutants
Fix nitrogen and produce antibiotics
Generate 50% of atmospheric oxygen
What are the major challenges in studying microbial communities?
Limited morphological diversity (cannot identify species based on shape)
Many microorganisms are unculturable in the lab
Microbes exist in complex consortia, making isolation difficult
How abundant and diverse are microbial communities in nature?
1 gram of soil contains 10⁷–10⁹ bacteria and up to 10,000 species
1 mL of seawater contains ~1 million bacteria and thousands of species
Only a small fraction of microbes have been cultivated
What is the “Great Plate Count Anomaly”?
Only ~1% of microbes observed under a microscope can be cultivated on agar plates, meaning traditional culturing methods underestimate microbial diversity.
What is epifluorescence microscopy, and how is it used in microbial enumeration?
Fluorescent DNA stains (e.g., DAPI, SYBR Green) are applied to the sample.
The sample is incubated in the dark.
Bacteria are counted using UV epifluorescence microscopy, giving a total count of microbes.
What is the difference between plate counts and direct counts?
Plate counts measure colony-forming units (cfu) and reflect viable bacteria.
Direct counts (e.g., microscopy) are always higher because many bacteria do not grow in lab conditions.
What is 16S rRNA gene sequencing, and why is it used in microbial studies?
16S rRNA is a conserved gene found in all prokaryotes.
It has variable and conserved regions, making it a useful phylogenetic marker.
Allows identification of unculturable bacteria.
What is the typical workflow for microbial community analysis?
Collect an environmental sample
Extract nucleic acids (DNA/RNA)
Amplify marker genes (e.g., 16S rRNA for bacteria, 18S for eukaryotes)
Sequence genes using high-throughput sequencing
Compare sequences to databases to identify microbes
What are functional genetic markers, and how are they used?
These are genes encoding key enzymes in metabolic pathways.
They help determine microbial functions (e.g., methane oxidation, nitrogen fixation).
Can be studied via PCR, cloning, and sequencing.
What is metagenomics, and how does it differ from traditional approaches?
Metagenomics analyzes all genetic material from an environmental sample.
Unlike PCR-based methods, it provides a broader view of taxonomic and functional diversity.
Uses shotgun sequencing or next-generation sequencing (NGS).
How are microbial genomes assembled from metagenomic data?
DNA extraction & sequencing
Assembly of sequencing reads into contigs
Binning (grouping sequences into species-level clusters)
Annotation (assigning functions to genes)
What is the pmoA gene, and why is it important?
pmoA encodes particulate methane monooxygenase (pMMO), an enzyme in methane oxidation.
Used to identify methanotrophic bacteria in environmental samples.
pmoA sequencing has revealed vast uncultivated diversity of methane-consuming microbes.
How do methanotrophs help regulate atmospheric methane?
Methanotrophs consume methane (CH₄) before it reaches the atmosphere.
Play a crucial role in reducing greenhouse gas emissions.
Found in environments like wetlands, rice fields, and oceans.
What are some modern approaches to microbial community analysis?
Metagenomics (whole-genome sequencing of microbial communities).
Metatranscriptomics (RNA sequencing to study gene expression).
Metaproteomics (analyzing proteins to understand microbial activity).
What is a biogeochemical cycle?
A natural pathway through which essential elements like carbon circulate between living organisms and the environment.
What are the main carbon reservoirs?
The ocean, continents (terrestrial systems), atmosphere, and the Earth’s crust (including fossil fuels and sediments).
What does the Keeling Curve represent?
A graph showing the rise of atmospheric CO₂ concentrations over time, highlighting the impact of human activities on global carbon levels.
What is primary production?
The generation of organic matter from CO₂ by photoautotrophs and chemolithoautotrophs, forming the base of the food web.
Which organisms are significant primary producers in the marine environment?
Phytoplankton, including cyanobacteria and algae such as Emiliania huxleyi.
What is carbon fixation?
The process by which autotrophic organisms convert CO₂ into organic compounds using energy from light or inorganic molecules.
What is methanogenesis?
A biological process where methanogenic archaea produce methane (CH₄) from CO₂ and hydrogen under anaerobic conditions.
What is the role of methanotrophs in the carbon cycle?
They consume methane and convert it back into CO₂, playing a crucial role in limiting atmospheric methane levels.
How does respiration contribute to the carbon cycle?
Plants, animals, and microorganisms break down organic matter, releasing CO₂ back into the atmosphere.
What is the global warming potential of methane compared to CO₂?
Methane has a global warming potential 21 times greater than that of CO₂.
What is the significance of hydrothermal vent ecosystems in the carbon cycle?
They host chemolithoautotrophic microorganisms that fix carbon in the absence of sunlight using energy from chemical reactions.
What are the three main methanogenesis pathways?
Hydrogenotrophic (CO₂/H₂ reduction), methylotrophic (reduction of methyl groups), and acetoclastic (breakdown of acetate).
How does permafrost thawing affect the carbon cycle?
Thawing releases stored carbon as CO₂ and methane, contributing to climate feedback and accelerating global warming.
What role do sulfate-reducing bacteria play in the carbon cycle?
They degrade organic matter in marine sediments under anaerobic conditions, producing hydrogen sulfide.
What is a gigaton (Gt) in the context of carbon reservoirs?
A unit of measurement equal to 1 billion tons (1 trillion kilograms) of carbon stored in a reservoir.
Why is nitrogen essential for living organisms?
Nitrogen is a key component of proteins, nucleic acids, and other essential biomolecules required for life.
What are the major microbial transformations of nitrogen?
Nitrification, denitrification, ammonification (mineralization), assimilation, and nitrogen fixation.
What is nitrogen fixation?
The conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) by nitrogen-fixing bacteria and archaea.
What happens during nitrification?
Ammonia (NH₃) is oxidized to nitrite (NO₂⁻) by Nitrosomonas bacteria, then to nitrate (NO₃⁻) by Nitrobacter bacteria.
What is denitrification?
The microbial reduction of nitrate (NO₃⁻) and nitrite (NO₂⁻) to gaseous nitrogen compounds such as nitric oxide (NO), nitrous oxide (N₂O), and nitrogen gas (N₂).
What environmental factors influence nitrification?
pH, oxygen availability, soil structure, moisture, and temperature.
What is eutrophication, and how is it linked to nitrogen enrichment?
Eutrophication is the excessive growth of plants and algae in water bodies caused by nutrient runoff, particularly nitrate and ammonia.
What is methemoglobinemia (blue baby syndrome)?
A condition caused by high nitrate concentrations in drinking water that reduces the oxygen-carrying capacity of blood, especially in infants.
What role does urea play in the nitrogen cycle?
Urea, produced by organisms and used as fertilizer, is rapidly broken down into ammonia (NH₃) and carbon dioxide (CO₂) by microbial urease.
What is the impact of excessive fertilizer use on the nitrogen cycle?
It leads to nitrate leaching, groundwater contamination, eutrophication, and increased emissions of greenhouse gases like N₂O.
What are Nitrate Vulnerable Zones (NVZs)?
Areas designated to reduce nitrate pollution from agriculture, requiring farmers to follow specific guidelines for fertilizer application.
How does denitrification contribute to climate change?
It produces nitrous oxide (N₂O), a potent greenhouse gas that contributes to global warming.
What are the consequences of nitrate leaching?
Contamination of groundwater, reduced soil fertility, and the potential for eutrophication in nearby water bodies.
What is the role of Nitrosomonas and Nitrobacter bacteria in the nitrogen cycle?
Nitrosomonas oxidizes ammonia to nitrite, and Nitrobacter further oxidizes nitrite to nitrate.
How have human activities altered the global nitrogen cycle?
Industrial fertilizer production has doubled nitrogen inputs to terrestrial ecosystems, leading to increased nitrogen pollution and climate change impacts.
