19. Organisms and their environment Flashcards
19.1 Energy flow 19.2 Food chains and food webs 19.3 Nutrient cycles 19.4 Populations
Consumer
An organism that gets its energy by feeding on other organisms. They may be classed as primary, secondary, tertiary and quaternary according to their position in a food chain
Herbivore
An animal that gets its energy by eating plants
Carnivore
An animal that gets its energy by eating other animals
Decomposer
An organism that gets its energy from dead or waste organic material
Trophic level
The position of an organism in a food chain, food web or ecological pyramid
Organisms
Any living biological entity, such as an animal, plant, fungus, or bacterium
Respiration
Chemical reactions in cells that break down nutrient molecules to release energy
Carbohydrates
Compounds found in living things composed of carbon, hydrogen and oxygen
Biological systems
A group of organisms or organs that work together to carry out a particular task
Biomass
The dry mass of living material in each organism. If multiplied by the total number of organisms at that trophic level you get the total biomass of a species in that system
Detrivores
Animals that eat dead plants and animals
Detritus food chains
Food chains that start with dead organic materials
Efficiency of biomass transfer
(biomass in higher trophic level / Biomass in lower trophic level) * 100
Ecosystem
A unit containing the community of organisms and their environment, interacting together
Food chain
Showing the transfer of energy from one organism to the next, beginning with a producer
Food web
A network of interconnected food chains
Removing Carbon Dioxide from air (CC)
Photosynthesis
carbon dioxide + water → glucose + oxygen
Feeding and decomposition in living cycles (CC)
Animals eat plants –> Digest carbon compounds.
Decomposers feed on dead animals + waste materials –> digest carbon compounds.
Returning carbon dioxide to the air (CC)
Respiration - glucose + oxygen → carbon dioxide + water
Combustion - Burning of fossil fuels (compressed organisms) / trees + plants releases carbon
Where is carbon stored
Atmosphere (Gas)
Ocean (Carbon dioxide dissolves in water - bicarbonate salt)
Land Biomass (Dry matter in organisms (plants + animals))
Fossil Fuels
What is nitrogen used for?
To create amino acids.
To create nitrate ions, ammonium ions –> minerals needed for living organisms.
Nitrogen Fixation (NC)
Nitrogen fixation is the process by which unreactive nitrogen gas is converted into more reactive forms of nitrogen.
Lightning - Energy makes nitrogen gas combine with oxygen forming nitrogen dioxide / nitric oxide. Dissolve in rain –> wash into soil.
Nitrogen-fixing bacteria - Bacteria that convert nitrogen gas or ammonium ions (in soil) into nitrates to be used by plants. Live freely in soil or inside nodules of leguminous plants (beans/plants).
Denitrification (NC)
Process that converts nitrates from the soil into nitrogen gas.
Denitrifying bacteria in soil.
How do animals consume nitrogen?
We eat plants that have consumed nitrogen from soil / nitrogen fixing bacteria.
Plant absorbtion (NC)
Plants absorb nitrate ions through root hair cells + active transport. –> use this to make amino acids –> make proteins –> transferred to animals been eaten –> digested to form amino acids –> make proteins etc.
Nitrogen from animals to plants (NC)
Deamination - The removal of the nitrogen-containing part of amino acids to form urea.
Excess amino acids transported to liver for deamination. Urea excreted through kidneys in urine.
Decomposition - Decomposers break down plants and animal protein to form ammonium ions –> can be nitrified to form nitrate ions. –> either absorbed by plants or dentrified.
Nitrification (NC)
Ammonium ions in soil converted to nitrate ions using nitrifying bactera in soil.
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 affecting population growth rate.
Food supply - Enough food/shortages.
Predation - too many/too few predators in relation to prey
Disease - Epidemics can cause fall in population
Competition - for resources (water, food, territory)
Population factors affecting growth curve
Number of births - Increases size
Immigration - Increases size
Number of deaths - Decreases size
Emigration - Decreases size
Stable population
number of births + immigration = number of deaths + emigration
Sigmoid curve of population growth
An s-shaped curve that plots the change in population as it varies due to environmental factors.
Sigmoid curve - Lag phase
Slow increase in population, after a new species has been introduced to an environment.
Sigmoid curve - Exponential (log) phase
Resources are plentiful –> individuals reproduce at a high rate –> exponential increas in population size
Sigmoid curve - Stationary phase
Maximum size of population reached (carrying capacity) –> competition for resources is high –> not all individuals will get teh resources they need to survive.
Sigmoid curve - Death phase
Rapid decrease in the size of population. Caused by new predator, disease, competing species, drought etc.
Carrying Capacity
The maximum population size of a species that can be sustained by its environment.
Limiting Factor / Environmental Resistance Factors
The variable in the environment that controls the rate, growth or abundance of a biological processes. For instance, temperature can be the limiting factor in the growth of a plant.
