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What is a key characteristic of ecological succession?
What is a key characteristic of ecological succession?
What happens to energy as it is transformed through trophic levels in an ecosystem?
What happens to energy as it is transformed through trophic levels in an ecosystem?
Which process describes the recovery of an ecosystem after a disturbance?
Which process describes the recovery of an ecosystem after a disturbance?
Which group of organisms is found at the second trophic level in a food chain?
Which group of organisms is found at the second trophic level in a food chain?
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What is a characteristic of primary succession?
What is a characteristic of primary succession?
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How does the flow of energy relate to thermodynamics in ecosystems?
How does the flow of energy relate to thermodynamics in ecosystems?
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Which of the following best describes the role of decomposers in an ecosystem?
Which of the following best describes the role of decomposers in an ecosystem?
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In terms of energy flow, which statement is true regarding food chains?
In terms of energy flow, which statement is true regarding food chains?
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Which cycle is primarily responsible for the replenishment of oxygen in an ecosystem?
Which cycle is primarily responsible for the replenishment of oxygen in an ecosystem?
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What is the primary source of energy flow in ecosystems?
What is the primary source of energy flow in ecosystems?
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Which cycle involves the conversion of nitrogen gas into forms usable by living organisms?
Which cycle involves the conversion of nitrogen gas into forms usable by living organisms?
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What is the significance of keystone species in an ecosystem?
What is the significance of keystone species in an ecosystem?
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Which process in ecological succession allows for the establishment of more complex ecosystems over time?
Which process in ecological succession allows for the establishment of more complex ecosystems over time?
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Which cycle is crucial for the transfer of carbon among living organisms and the atmosphere?
Which cycle is crucial for the transfer of carbon among living organisms and the atmosphere?
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In the energy flow cycle of ecosystems, which component is essential for energy transformation?
In the energy flow cycle of ecosystems, which component is essential for energy transformation?
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What role does water play in the functioning of ecosystems?
What role does water play in the functioning of ecosystems?
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What represents the last trophic level in an ecosystem?
What represents the last trophic level in an ecosystem?
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Which of the following best describes a grazing food chain?
Which of the following best describes a grazing food chain?
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What defines a food web in an ecosystem?
What defines a food web in an ecosystem?
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How does the extinction of one species in a food chain affect other species?
How does the extinction of one species in a food chain affect other species?
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What role do food chains and food webs play in ecosystems?
What role do food chains and food webs play in ecosystems?
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What is the process of bio-magnification?
What is the process of bio-magnification?
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What best characterizes ecological pyramids?
What best characterizes ecological pyramids?
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Which type of food chain starts with dead organic matter?
Which type of food chain starts with dead organic matter?
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Study Notes
Ecosystem Overview
- Ecosystems are communities of living organisms interacting in a specific environment.
- Living components (biotic): trees, plants, animals, insects, microorganisms.
- Non-living components (abiotic): sunlight, temperature, chemical elements (oxygen, nutrients).
- Biotic and abiotic components connect through nutrient cycles and energy flow.
Ecosystem Classification
- Based on Nature: Natural (forests, grasslands, deserts, marine, freshwater) and manmade/artificial (aquariums, crop fields, flowerbeds).
- Based on Duration: Temporary (rain-fed ponds, laboratory cultures) or permanent (forests, lakes).
- Based on Size: Small/micro ecosystems (flowerpots, logs) or large/macro ecosystems (oceans, deserts).
Ecosystem Degradation
- Human activities disrupt ecosystems.
- Extinction of plant/animal species (some species, like bees, are keystone species - their elimination severely impacts the ecosystem).
- Extinction causes: land use change (deforestation of forests, draining wetlands for agriculture), pollution, depletion of resources caused by growing population and consumption.
Ecosystem Structure
- Living (biotic) components include producers, consumers, and decomposers.
- Producers: green plants, some bacteria (autotrophs), manufacture food.
- Consumers: animals obtaining food from producers (herbivores, carnivores, omnivores).
- Decomposers: bacteria and fungi that decompose dead organic matter (microconsumers).
- Non-living (abiotic) components include physical (climate factors, light, temperature, humidity) and chemical (inorganic substances like C, N2, O2, CO2, H2O, and organic compounds like carbohydrates, proteins, lipids).
Ecosystem Function
- Energy cycles: Movement of energy through the ecosystem (the Sun is the initial source).
- Food chains: Sequence of eating and being eaten.
- Diversity-interlinkages: Relationships within the ecosystem.
- Nutrient cycles: (biogeochemical cycles) movement of chemical elements within the ecosystem.
- Evolution: Long-term changes in the ecosystem.
Energy Flow
- Energy controlled by water, carbon, oxygen, nitrogen, and energy cycles.
- Energy flow within the ecosystem is vital for the growth and regeneration of plant and animal species.
- Energy (from sunlight!) drives the interconnected processes.
Water Cycle
- Water cycles through the environment: evaporation, condensation, precipitation, transpiration, snowmelt, storage in ice/snow.
- Ground and surface water storage play important roles.
Carbon Cycle
- Carbon exists in organic compounds in abiotic and biotic parts.
- Carbon forms the base of plant and animal tissues.
- Carbon dioxide (CO2) is important in the atmosphere.
- Photosynthesis converts CO2 into carbohydrates (releasing O2 ).
- Respiration and decay return carbon to the atmosphere.
Oxygen Cycle
- Plants release oxygen during photosynthesis.
- Animals absorb oxygen for respiration.
- The cycle links to the carbon cycle.
Nitrogen Cycle
- About 78% of the atmosphere is nitrogen (in a unusable form).
- Living things use nitrogen compounds (proteins and other chemicals).
- Bacteria convert nitrogen into usable forms.
- Some fixed nitrogen returns to the atmosphere (denitrification).
Nitrogen Cycle (continued)
- Certain bacteria (Pseudomonas and Clostridium) perform denitrification in anaerobic conditions (absence of oxygen).
- This method uses nitrates as an oxygen substitute during respiration.
- The process returns nitrogen to the atmosphere.
Energy Cycle (continued)
- The sun is the primary energy source for most ecosystems.
- Energy eventually becomes heat.
- Organisms transfer energy and nutrients in food chains.
- Decomposers break down dead organisms, releasing inorganic nutrients (which then recycle).
Energy Cycles in Nature
- Energy cannot be created or destroyed, only transformed.
- Energy is lost as heat in energy transformations.
- Cycles are crucial to maintain life on Earth.
- Disrupting these cycles negatively affects the planet, which can cause a degraded environment.
Ecological Pyramids
- Graphical representation of tropic levels in an ecosystem.
- Producers on the bottom, successive trophic levels upward.
- Biomass and number of organisms decrease at higher levels due to energy loss as heat.
Pyramid of Numbers
- Represents the number of individuals in each trophic level.
- Producers (e.g., grasses) usually have the largest numbers.
- Numbers decrease as you move up the food chain.
Pyramid of Biomass
- Represents the mass/weight of living organisms.
- Generally upright in terrestrial ecosystems; inverted in some aquatic systems (e.g., productivity in the upper levels is higher than lower levels).
Pyramid of Energy
- Shows the flow of energy through trophic levels, organisms' roles are highlighted.
- Large energy losses (as heat) at higher levels during respiration.
- Always shows an upright shape, energy flows from lower trophic levels to progressively higher ones.
Forest Ecosystem
- Dense area with tall trees, supporting many species.
- Found in areas with moderate to high rainfall.
- Vital habitats, high biodiversity.
Grassland Ecosystem
- Characterized by grasses, some scattered shrubs/trees.
- Limited grazing improves grasslands' primary production; overgrazing leads to degradation.
- Divided into tropical, temperate, and polar.
Desert Ecosystem
- Less than 25 cm of rainfall.
- Dry atmosphere, poor insulator.
- Classified into tropical, temperate, and cold deserts.
Aquatic Ecosystems
- Deals with bodies of water.
- Fresh water (ponds, streams, lakes, rivers).
- Salt water (oceans, estuaries).
Fresh Water Ecosystem (Pond)
- Temporary, seasonal.
- Stagnant fresh water bodies.
- Susceptible to pollution.
- Lentic ecosystems (involve stagnant or standing water.)
Lake Ecosystem
- Large, shallow bodies of water.
- Supplied by rainfall, snowmelt, and streams.
- Types: oligotrophic (low nutrients), eutrophic (excessive nutrients), dystrophic (low pH, high humidity).
River Ecosystem
- Running water (aerated).
- Fresh water.
- High oxygen content; low numbers of animals.
- Significant for nutrient deposition.
Saltwater Ecosystem (Ocean)
- Covers most of Earth's surface.
- High salinity, nutrient-rich shallow water (high primary productivity).
- Diverse organisms and zones (e.g., euphotic, bathyal, abyssal).
Food Chains
- Sequence of eating/being eaten in an ecosystem.
- Starts with producers (plants), ends with consumers (animals).
- When organisms die, decomposers recycle nutrients into the ecosystem.
- Energy is lost (as heat) at each level.
Food Webs
- Interconnected pattern of food chains.
- Multiple paths for energy flow through different types of organisms.
Food Chain vs Food Web
- Linear food chains are easily disrupted when a species becomes extinct.
- Food webs are more resilient to such disruptions as numerous options for energy transfer are present at each trophic level.
Significance of Food Chains & Food Webs
- Maintain the ecological balance.
- Regulate the population size of different trophic levels.
- Enable energy and nutrient cycling.
- Show bio-magnification (increase in concentration of bio-degradable material at each level)
Tropical vs Temperate vs Polar Grasslands
- Different climates affect plant types, animals present.
- Tropical grasslands (savanna): high temperatures, moderate rainfall, tall grasses.
- Temperate grasslands: moderate temperatures, alternating hot and cold weather, grasses.
- Polar grasslands: cold temperatures, ice and snow.
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