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Questions and Answers
In which layer of the atmosphere is air suitable for the survival of terrestrial plants and animals found?
What is the primary reason the atmosphere is not hospitable for microorganisms?
Which of the following is NOT a physical property affecting the transport and settling of bioaerosols?
Which environmental factor contributes to the influx of airborne microorganisms by affecting their survival?
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Which of the following microorganisms is known to be quite resistant to environmental stress during air transport?
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What aspect is included in biological or ecological regulation?
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In wet weather, what phenomenon occurs that affects airborne microorganisms?
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Which characteristic is most important for the physical properties of bioaerosols?
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What characterizes a natural ecosystem?
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Which of the following is NOT a type of natural ecosystem?
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Which component of an ecosystem includes living organisms?
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What distinguishes macroconsumers from microconsumers?
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Which statement about terrestrial ecosystems is correct?
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What role do soil ecosystems play in biogeochemical cycles?
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Which of the following accurately describes prokaryotes in soil ecosystems?
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What is a characteristic of subsurface soil microbial communities?
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What is one of the main differences between Gram-positive and Gram-negative bacteria in soil?
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Which type of soil bacteria is known for transforming ammonium to nitrite?
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What role do soil fungi primarily play in the environment?
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Which characteristic of aquatic ecosystems is true regarding their composition?
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What type of bacteria is associated with thermal springs?
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In which layer of water are most oxygen-rich microorganisms found?
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What is the primary function of Azotobacter and Rhizobium in terrestrial ecosystems?
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How does the concentration of dissolved oxygen affect the microorganisms in lakes and marine environments?
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Study Notes
Natural Ecosystems
- Natural ecosystems are found in nature, where organisms interact freely with their environment. These ecosystems operate naturally without significant human interference.
- Types of natural ecosystems include terrestrial (forests, grasslands, deserts) and aquatic (freshwater and marine).
Domains of Natural Environment
- The natural environment consists of the lithosphere (earth's crust), hydrosphere (water), atmosphere (air), and biosphere (living things).
Components of an Ecosystem
- Abiotic components: Non-living factors such as inorganic substances, organic compounds, and climate factors.
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Biotic components: Living organisms:
- Autotrophs: Produce their own food (plants).
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Heterotrophs: Consume other organisms for food:
- Macroconsumers: Herbivores, carnivores, omnivores.
- Microconsumers: Decomposers such as bacteria, actinomycetes, and fungi.
Terrestrial Ecosystems
- These are the richest and most complex ecosystems, ranging from rainforests to deserts.
- The soil harbors a diverse microbial population.
- Microbial species density and composition are influenced by environmental conditions.
- The soil surface is dominated by archaea, bacteria, fungi, algae, and protozoa.
- Subsurface microbial communities are less diverse and abundant.
- Nutrients are more limited in the subsurface, leading to a higher proportion of non-culturable organisms.
- Soil ecosystems play crucial roles in biogeochemical cycles, including water and nutrient cycling.
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Microorganisms in terrestrial ecosystems:
- Prokaryotes are the most abundant soil inhabitants.
- Gram-positive (G+) bacteria are more prevalent than Gram-negative (G-) bacteria, including spore-forming Bacillus and Clostridium.
- Filamentous G+ bacteria like Streptomyces produce hyphae.
- Chemoheterotrophic G- bacteria found in terrestrial ecosystems include Azotobacter, Agrobacterium, Rhizobium, Pseudomonas.
- Chemoautotrophs like Nitrosomonas (ammonia to nitrite) and Nitrobacter (nitrite to nitrate) are important for nitrogen cycling.
- Fungi are primarily aerobic and found in the top layers of soil. They decompose plant matter, breaking down complex molecules like lignin and cellulose.
- Many soil bacteria and fungi contribute to nutrient cycling and bioremediation of organic contaminants.
- Protists are also present in most soils.
- Algae rely on sunlight and most protozoans need oxygen, so they are found closer to the soil surface.
Aquatic Ecosystems
- Aquatic ecosystems cover over 70% of the Earth's surface.
- Types include freshwater (springs, streams, rivers, lakes) and marine (seas, oceans).
- Different types of springs harbor unique microbial communities: cold, thermal, hot, and specialized (iron, sulfur, radioactive).
- Cold springs are inhabited by bacteria and algae, while thermal springs support archaea and thermophilic bacteria.
- Iron springs are home to Gallionella and Sphaerotilus, while sulfur springs support photosynthetic and non-photosynthetic sulfur bacteria.
- Streams and rivers accumulate organic matter from surrounding terrestrial environments, leading to a diverse microbial population.
- The abundance and type of microorganisms in lakes and marine environments depend on factors like oxygen concentration, nutrient levels, temperature, and sunlight.
- Oxygen-rich upper layers support a variety of photosynthetic organisms.
Atmosphere
- The atmosphere has various layers, extending up to 1000 km.
- Air content and pressure vary in different layers.
- The troposphere, closest to Earth, supports terrestrial plants and animals.
- The atmosphere also contains microorganisms, water droplets, dust particles, and other matter.
- The atmosphere is not ideal for microorganisms due to temperature variations, low organic matter content, and limited available water.
Bioaerosols
- Airborne biological particles are called bioaerosols.
- They are polydispersed droplets or particles varying in size (0.5 to 30 µm).
- Bioaerosols are released from soil or water surfaces, transported through the air, and eventually deposited on surfaces.
- Transport and settling of bioaerosols are influenced by their physical properties (size, density, shape) and environmental factors (air currents, temperature, humidity).
Bioaerosols and Microorganisms
- Temperature and humidity influence the number of airborne microorganisms.
- Fungi spores like Cladosporium and Nigrospora increase in outdoor air.
- Bacterial release from plant surfaces is higher in warm, dry conditions.
- Rain washes microorganisms from the air.
- Microorganisms must adapt to environmental stresses like desiccation, humidity, and radiation to survive in the air.
- Harsh conditions reduce the number of viable airborne microorganisms.
- There is variability in survival between different groups of microorganisms and even within genera.
- Fungal spores and enteric viruses are resistant to environmental stress during air transport.
- Bacteria and algae are more susceptible, while bacterial endospores like Bacillus sp. are highly resistant.
Functional Aspects of an Ecosystem
- Ecosystem functions include:
- Biological energy flow (production and respiration rates).
- Nutrient cycling.
- Biological or ecological regulation (organisms regulating their environment and vice versa).
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Description
Explore the fascinating world of natural ecosystems including their types, components, and domains. Understand how abiotic and biotic factors interact within terrestrial and aquatic environments. This quiz covers fundamental concepts essential for understanding ecology.
