Ecology

All of the organisms of one species that live in the same place at the same time

All the populations of all the species that live in the same ecosystem at the same time

The place where an organism live

A distinct, self supporting system of organisms interacting with each other and with the physical environment

The amount of variations shown by a species in an ecosystem

Climate (light intensity, temperature, water availability) Hours of daylight Pollution Soil conditions

Availability of food and competition for food resources Disease Presence of pollinating insects Availability of nest sites Predation

Plants which photosynthesise to produce their own food materials

It’s an animal which eats the producer and is also a herbivore

It’s an animal that eats the primary consumer and is also a carnivore

The simplest way of showing feeding relationships within the ecosystem In a food chain the arrows are showing the direction of energy transfer

It’s a group of interlinked food chains Food webs are more realistic representation of what happens in an ecosystem, it would be very rare for a food chain to exist in isolation

They represent the number of organisms in each trophic level in a food chain, irrespective of their mass The producer is always at the base

Shows the total mass of the organisms in each trophic level, irrespective of their numbers There is always going to be a pyramid shape as the energy is lost between each trophic level, so biomass always decrease as we move up the food chain

The total mass of organisms, this is the mass of plant or animal material after water has been removed by drying it in an oven

When the primary consumer eats the producer, not all of the material in the producer ends up in the consumer, there are some loses (for example grass): some parts of the grass is not eaten, some parts are not digested and so are not absorbed, some of the materials absorbed form excretory product, many of the materials are respired to release energy with the loss of carbon dioxide and water Only a small fraction of the materials in the grass upends up in new cells in a rabbit, only 10% of energy is transferred to the next trophic level, similar loses are repeated each stage in the food chain, so smaller and smaller amounts of biomass are available for growth at successive trophic levels, reflecting the shape of pyramids of biomass

Respiration Combustion Photosynthesis Decomposition

Animals respire releasing carbon dioxide into the atmosphere

Photosynthesis fixes carbon atoms from carbon dioxide into organic compounds

Decomposition bacteria and fungi respire releasing carbon dioxide into the atmosphere

Combustion releases carbon dioxide into the atmosphere when the fossil fuels are burned

Nitrifying bacteria Denitrifying bacteria Nitrogen-fixing bacteria

They oxidise ammonia into nitrite and then into nitrates

They use nitrates as an energy source and convert them into nitrogen gas