Energy And Matter In Ecosystems Flashcards
(40 cards)
Energy
The capacity to cause change, particularly to do work
Energy source
The sun provides most of earths energy in a form of electromagnetic radiation that is known as as solar energy
A biogeographical cycle
Refers to the pathway of matter through the living components (organisms) and non-living components (such as soil, rocks, water and the atmosphere) of an ecosystem
A geochemical cycle
Refers to the chemical interactions that exist in crustal and subcrustal reservoirs, such as the deep earth and lithosphere (crust)
Biotic components of an ecosystem
Light energy enters an ecosystem via producers (plants and algae)
All organisms rely on producers either directly or indirectly
Energy is stored in chemical bonds in the organic compounds and is released when the chemical bonds are broken
Photosynthesis
Carbon dioxide + water —> glucose + oxygen
Only producers perform photosynthesis
Biomass
The chemical energy stored in plants as organic matter can be measured
Is the total mass of biological matter (living or dead) in a given area
Photosynthesis efficiency
How well a producer converts light energy into carbohydrates during photosynthesis
Net primary productivity (NPP)
Is the remaining amount of energy that is available to consumers
Net production = gross production - energy used in respiration
Consumers (1)
An organisms that depends on other organisms for its nutrients and energy requirements
They extract energy stored in chemical bonds by a process called cellular respiration
Cellular respiration
Is a metabolic process. It is the breakdown of organic matter in order to release energy
Glucose + oxygen —> carbon dioxide + water (+ energy in the form of ATP)
Both producers and consumers perform cellular respiration
Food chains and food webs
Are examples of qualitative, predictive models that allow ecologists to monitor raw sustainability of feeding relationships in an ecosystem
The position an organism occupies in a food chain or web is called its trophic level
A generalised food chain
Sunlight - producer - primary consumer (herbivore) - secondary consumer (second-order consumer) - tertiary consumer (third-order consumer) - top carnivore (apex predator)
A food web
Is a group of food chains that are linked together, showing the interactions between food chains within a community
Plants are autotrophs: they make their own food by transforming light energy from the sun during photosynthesis
Process of energy through food chain
- potential energy stored in plants
- primary consumers (herbivores) feed on producers (plants)
- carnivores and omnivores are secondary consumers
- secondary consumers feed on primary consumers
- at each trophic level in the chain, a proportion of the available energy is used during essential biological processes and lost due to inefficiencies during transfer. Some energy is lost from the food chain as chemical energy in organic wastes of dead plant and animal tissues, collectively called detritus
- energy from the top consumers is transferred to scavengers and detritivores.
Scavengers are animals that feed no the dead remains of other animals.
Detritivores feed on the detritus and help speed up the process of decay by breaking it down into smaller pieces.
Decomposes continue this process, returning these nutrients to the soil or water
Energy loss in food chains
Progressively less energy is available at each tropic level as you move up a food chain
On average 10% of the energy at one trophic level is passed on to the next level
The remaining 90% is lost to the surroundings as heat energy and chemical energy in wastes
The efficiency of energy transfer can vary from less than 0.1% to well over 10%
Trophic efficiency
The percentage of the energy at one trophic level that is transferred to the next trophic level
Pyramids of numbers
In which the size of each tier is proportional to the number of individuals parent at each trophic level
A typical food chain tends to have a drop in the number of organisms at each tropic level. This is represented as a pyramid or numbers. Pyramids or numbers may not always have an apex representing high trophies levels.
E.g. a single very large producer, such as a eucalyptus tree, may support a large number of primary consumers.
In these cases, an inverted pyramid of numbers results. Inverted pyramids of numbers can also result when communities contain parasites.
Food webs are integrated food chains
Most species depend on more than one kind of organisms for their food. A herbivore as a primary consumer will feed on number of species of plants and, in turn, will be earth by several different kinds of carnivores
The feature that distinguishes a food chain from a food web is that an organism can occupy different trophic levels in different food chains. In other words food webs represent the dynamic interactions between organisms in an ecosystem
Humans are omnivorous consumers, humans can obtain more of the energy available in plants, because they are not exposed to the energy losses that occur by eating foods higher up the food chain. When humans consume livestock, they only obtain 1% of the total energy that is available in producers. Members of populations of different species move in and out of different ecosystems, so an organism may be part of one food chain or we at one time but not at another time
Pyramids of biomass
Each tier represents the total dry weight of organisms at each tropic level
A pyramid of biomass is another type of ecological pyramid that can be constructed for a community. Pyramid of biomass records the total mass of (amount of dry organic matter) of organisms at each level. Measurements can be made at one particular time or thy can be calculated as rates (productivity) from measurement of dry mass in a given area for the duration of a year (e.g. g m -2 year -1)
Almost always pyramidal in shape, certain circumstances may give an inverted pyramid
Pyramids of energy
The size of each tier is proportional to the production (e.g. in kJ) of each trophic level
Although pyramids of numbers and biomass provide ecologists with useful information, to get fuller understanding of what happened to energy transfer in communities, pyramids of energy aer constructed.
Pyramids of energy are expressed in units of energy per area in a given time. They show the rate at which energy is transferred from one trophies level to another. Pyramids of energy allow ecologists to describe the rate of energy transfer in a community . This allows them to make predictions about weather a community can be sustained and hat impact any changes to rates of energy transfer will have on the community.
Pyramids of energy can never be inverted in the way that pyramids of numbers or biomass sometimes are
Drawing pyramids of energy
- The bottom level should always represent a producer
- Subsequent levels should be labelled primary consumer, secondary consumer and tertiary consumer
- As far as possible, each trophic level should be drawn to scale. Unless you have alternative data, measure one-tenth the length of the preceding trophic level (this represents the average energy transfer efficiency of 10%)
- Use labelled arrows to indicate energy leaving each trophic level in the form of heat
Biogeochemical cycle of matter
Important difference between energy and matter is that the sun provides a constant, external supply of energy, while the total matter is a fixed resource and therefore matter must be recycled
Producers
Also called autotrophs, include green plants
Green pigment, chlorophyll enables plants to trap energy from sun during photosynthesis
Energy is used in combining carbon dioxide and water to produce food and oxygen, which becomes available to the consumers in the community
