Ecosystems (9-10) Flashcards
What is a population? What are its fundamental properties?
Organisms of the same species living in the same place at the same time.
Fundamental property: abundance (e.g. biomass).
What is a community? What are its fundamental properties?
Coexisting populations of different species.
Fundamental properties: species diversity, food web structure.
What is an ecosystem? What are its fundamental properties?
Community of organisms and their physical environment.
All organisms in an area + physical environment + biotic and abiotic interactions
Fundamental properties: nutrient cycling, energy flow.
What is the simplest ecosystem?
One species that produces its own food from inorganic compounds + one species that decomposes wastes of the first species.
Primary producers and decomposes.
Define the different trophic levels of an ecosystem:
- Decomposes: breakdown feces and dead organisms to recycle matter so that it is available for primary producers.
- Primary producers: autotrophic.
- Photoautotrophs: make their own food using solar energy and nutrients around them
- Chemoautotrophs: make their own food from chemical energy and nutrients around them - Primary consumers: heterotrophic (get energy from consuming others).
- herbivores (feed on primary producers). - Secondary consumers: heterotrophic.
- carnivores (feed on primary consumers).
What is Liebig’s law of the minimum?
Biological growth is not controlled by total resource availability, but rather by the availability of the scarcest resource, which is known as the limiting factor.
Limiting factors can be environmental conditions (temperature, water, sunlight, nutrients).
Primary production in terrestrial systems is limited by what? What about in aquatic systems?
- Water.
- when water is scarce, photosynthesis stops. - Nutrients.
- fertilizer stimulate crop production.
- N is often the limiting nutrient.
Aquatic systems: nutrient limited
- inadvertent addition of nutrients may stimulate unwanted production.
Explain the effects of bottom-up control and top-down control:
Explains what happens when we add a fourth trophic level (tertiary consumer).
Bottom-up: increased production results in greater productivity at all higher trophic levels
- everyone benefits from an increase of nutrients
Top-down: consumers depress the trophic level on which they feed, indirectly increasing the next lower trophic level.
- organisms on top dictate what happens.
Tertiary consumer: results in trophic cascade linking all trophic levels in a community.
- the relative biomass of trophic levels alternate under top-down controls.
What is productivity?
The creation of new organic matter.
- changes in biomass per unit time
- changes in energy per unity area per unit time
What are the 5 facts about energy flow and productivity?
- Energy is transferred along food chains from one trophic level to the next.
- Energy always dissipates as it moves from one trophic level to the next.
- Biomass tends to decrease up the food chain.
- Some biomass pyramids are inverted.
- Energy pyramids are never inverted.
Why do food chains typically only have 4 trophic levels?
- Longer chains tend to be unstable.
- Increasingly less energy reaches higher trophic levels.
Why does energy dissipate while going through trophic levels?
- Not all energy consumed by an animal is retained: some energy is excreted, some energy is respired as waste heat.
- Feeding inefficiencies exist: not all available food is consumed.
What are the 2 laws of thermodynamics?
- Conservation of matter and energy.
- matter and energy are not created or destroyed, just transformed.
- ecosystems are transformation systems (input-output machines) for energy and matter. - Energy degradation (entropy).
- energy moves from an organized, useful form to a disorganized, less useful form.
- energy cannot be recycled to its original state of organized, high-quality usefulness.
- energy dissipates and can’t be used.
Breakdown the following equation:
Respiration = Cellular respiration
Respiration = (formula for cellular respiration) + energy
Energy = ATP + heat
ATP is used as an energy currency at the cellular level. Eventually, all energy in ATP is lost as heat.
What is the energy balance equation?
What goes in = what goes out.
Input = output + death + respiration + excretion
