30 Questions
What does species richness refer to in an ecosystem?
The total number of different species present
Which factor influences the primary productivity of an ecosystem?
Amount of energy flow in the food chain
In terms of ecosystems, what is the ecological niche concept related to?
The interspecific relationships between species
Which statement best describes matter and energy flow in ecosystems?
Energy flows from the abiotic environment to organisms, while matter cycles within the ecosystem
What is the relationship between primary productivity and population levels in an ecosystem?
Higher primary productivity leads to higher population levels
How does community composition change along a moisture gradient?
It changes continually, independent of each species' abundance pattern
What causes greatly different plant communities on normal and serpentine soils?
Interaction between plant communities and abiotic factors
What is the key factor that determines the number of trophic levels in an ecosystem?
Energy availability
Which process results in the synthesis of new organic matter at each trophic level?
Gross primary productivity
Why can't organisms recycle energy according to the text?
Because of the increase in entropy
What is a critical characteristic of biodiversity for the survival of top consumers?
Presence of multiple alternative food sources
What is the metabolic process of converting non-gaseous compounds into gaseous compounds like ammonia known as?
Nitrogen fixation
Which cycle involves the flow of matter from rocks to ocean sediment without a gaseous form?
Phosphate cycle
What term describes the rate at which organisms collectively synthesize new organic matter at each tropic level?
Gross primary productivity
What type of symbiosis is exemplified by the relationship between bees and flowers?
Mutualism
Which type of interaction exerts selective pressures or provides reproductive/survival advantages to a species?
Competition
In terms of matter, is the Earth considered a closed or open system?
Closed system
Which is a major source of inorganic carbon in aquatic ecosystems?
Aqueous bicarbonate
What is the main concern in the study of ecosystems?
The flow of energy and materials
Which ecosystem process involves anaerobic respiration by methanogenic bacteria?
Carbon cycle
What does an aquifer consist of?
Permeable underground layers of rocks, sand, and gravel saturated with water
What is the major sink of organic carbon in aquatic ecosystems?
Organisms
How does interspecific competition contribute to natural selection?
By exerting selective pressures that favor certain species over others
What is the fundamental niche of a species?
The niche based on physiological tolerance limits and resource needs
Which type of competition occurs when two species physically interact over access to resources?
Interference competition
According to the Principle of Competitive Exclusion, what happens if two species are competing for a limited resource?
The less efficient species will eventually eliminate the other locally
What happens to predator population sizes if there is uncontrolled predation?
Predators face extinction
In the context of predator-prey relationships, what effect does providing shelter for prey have on their population dynamics?
Prey and predator populations can sustain at low levels
How do interspecific competition and resource partitioning relate to each other?
Interspecific competition leads to resource partitioning
What ecological concept describes the species pattern differences in various localities based on their suitable conditions?
"Ecological Niche" concept
Study Notes
Ecosystems and Ecology
- Species seldom live alone and form ecosystems with other species in a habitat.
- An ecosystem involves organisms' behavior, interspecific relationships, interaction between organisms and the abiotic environment, matter, and energy flow.
Properties of Community
- Species richness: the number of species in an ecosystem.
- Primary productivity: the amount of energy produced, which determines population size.
Environmental Influence
- The environment influences species richness and primary productivity.
- Example: abundance of tree species along a moisture gradient, with a change in community composition.
Nitrogen Cycle
- Nitrogen sources: nitrates and ammonia.
- Nitrogen fixation: N2 → NH3.
- Nitrification: NH3 → NO3.
- Denitrification: NO3- / NH3 → N2.
- Nitrogen-fixing bacteria perform nitrogen fixation.
Phosphate Cycle
- Phosphate cycle has no gaseous form.
- Phosphate flows from rocks to ocean sediment.
Energy Flow
- Energy cannot be recycled due to entropy (the order of chaos).
- Organisms cannot convert heat energy into other forms of energy.
- The Earth functions as an open system regarding energy.
Flow of Energy in an Ecosystem
- Energy flows through tropic levels.
- Bacteria can be detritivores (decomposers).
Productivity
- Productivity: the rate at which organisms synthesize new organic matter.
- Gross primary productivity - cellular respiration = Net primary productivity.
- Each tropic level has its own productivity.
Biodiversity
- Biodiversity is crucial for the survival of top consumers.
- Diverse sources of species provide multiple food alternatives.
Symbiosis
- Symbiosis: elaborated, permanent relationships between two or more interacting species.
- Types of symbiosis:
- Mutualism: all interacting species benefit.
- Parasitism: one species benefits, the other is harmed.
- Commensalism: one species benefits, the other is not affected.
Interspecific Interaction and Natural Selection
- Interspecific interactions (competition, predation, parasitism, commensalism, and mutualism) exert selective pressures or provide reproductive/survival advantages.
Dynamics of Ecosystems - Matter and Energy
- Ecosystems: all living organisms in a particular place and their abiotic environment.
- Matter: a relatively closed system on Earth (no net output or input from the universe).
- Energy: an open system on Earth, constantly receiving sunlight.
Biogeochemical Cycles
- Carbon cycle
- Water cycle
- Nitrogen cycle
- Phosphate cycle
Carbon Cycle
- Major sources of inorganic carbon: atmospheric CO2, aqueous bicarbonate.
- Major sinks of organic carbon: organisms, fossil fuels.
- Terrestrial ecosystem: anaerobic respiration by methanogenic bacteria.
- Aquatic ecosystem: aquatic plants and phytoplankton.
Water Cycle
- Groundwater and aquifers: permeable, underground layers of rock, sand, and gravel saturated with water.
- Water table: accessible by plants and flows into streams.
Ecological Niche Concept
- Ecological niches: specific conditions in which a species grows best.
- Types of niches:
- Fundamental niche: entire range of physiological tolerance limits and resource needs.
- Realised niche: the niche a species can establish a stable population.
Competition
- Interspecific competition: occurs when two species use the same resource and there's not enough to satisfy both.
- Types of competition:
- Interference competition: physical interactions over access to resources.
- Exploitative competition: consumption of the same resources.
Predator-Prey Relationship
- Predator-prey relationships can lead to extinction of the predator if prey is over-consumed.
- Shelter can provide a balance between predator and prey populations.
Test your understanding of species interactions, ecosystems, community properties, and primary productivity in habitats. Explore the relationships between organisms and their environment in this quiz.
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