B12 - Organisms and their Environment Flashcards
Principle source of energy
The Sun
Producers
Organisms that produce their own organic nutrients usually using energy from sunlight
* plants are producers as they carry out photosynthesis to make glucose
Herbivore
An animal that gets its energy by eating plants (they are primary consumers)
Carnivore
An animal that gets its energy by eating other animals (they are secondary consumers)
Primary consumers
Feed on producers (herbivores)
Secondary consumers
Feed on primary consumers (carnivores/predators)
Tertiary consumers
Predators that feed on secondary consumers
Decomposers
Bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste by secreting enzymes to break them down
Autotrophic organisms (give 1 example)
Organisms which create their own food / produce their own energy (through the use of inorganic material)
* e.g. algae (and many other plants)
Heterotrophic organisms (give 1 example)
Organisms which gain energy and nutrients from other animals or plants (use organic material)
* e.g. sheep (can be both a carnivore or a herbivore)
Saprotrophic organisms (give 1 example)
Organisms that obtain their nutrients from dead or decaying organic matter
* e.g. mushroom
Food chain
Shows the transfer of energy from one organism to the next, starting with a producer
What do the arrows in a food chain show?
The transfer of energy by ingestion
Food web
A network of interconnected food chains
* more realistic as animals rarely exist on just one type of food source
Interdependence
How the change in one population can affect others within the food web
Pyramid of numbers
Shows how many organisms we are talking about at each level of a food chain
* width of the box indicated the number of organisms at that trophic level
Why are there fewer than 5 trophic levels in a food chain?
Due to the loss of energy between each level of consumers
How is energy lost between the trophic levels?
MRS GREN
Ecosystem
A unit containing all of the organisms and their environment, interacting together, in a given area, e.g. a lake
Trophic level
The position of an organism in a food chain or food web
How is energy passed between the trophic levels?
An organism eats another organism and gets the energy-rich molecules from it’s orey’s body
Population
A group of organisms of one species, living in the same area at the same time
Community
All of the populations of different species in an ecosystem
Factors controlling population growth (3)
- Food supply
- Predation
- Disease
