B4 Flashcards
What is an ecosystem
All the organisms and living conditions present in an area
What are all the organisms living within an ecosystem called
A community
What is a habitat
The place an organism lives (emg a pond)
What is a population
The total number of organisms in a species that live in a specific area
What is a producer
Organisms that make their own food through photosynthesis
What is a consumer
Organisms that cannot make their own food and must eat other organisms to gain energy
ALL ANIMALS ARE CONSUMERS
What are decomposers
A special group of consumers
They gain their energy by feeling on dead or decaying material
What is an autotroph
An organism which generates its own energy
What is a photoautotroph
An organism that uses simple inorganic molecules to synthesise complex organic molecules
How do photoautotrophs increase their biomass
Photoautotrophs absorb energy from the sun in photosynthesis and create glucose.
This is then turned into carbohydrates, fats and proteins, which are then used as energy stores for growth and repair
As an organism grows its biomass increases - the mass of living material
What is biomass
The total living mass of organisms in an area
How is energy transferred between organisms
Consumers eat producers, which pass on lipids, proteins, carbohydrates and glucose
This energy is stored and transferred in the production of atp.
This organism then grows and its biomass increases
What is a food chain
A chain that displays what an organism eats
The arrows show the biomass transfer from one organism to the next
What is a trophic level
Each step in a food chain
E.g a producer would be trophic level one
What is a food web
A complex ‘web’ of food chains that are interlinked.
These are needed as not only one animal is eaten by another. Usually it would have multiple predators
What are the main factors in an ecosystem
Biotic - living factors (E.g the plants and animals)
Abiotic - non-living (physical) factors (E.g the rainfall, temperature or wind speeds in an ecosystem)
How do biotic factors effect communities
Organisms may compete with each other for food and space
Competition is the main biotic factor
How does light intensity (abiotic factor) affect communities
Light intensity is needed for photosynthesis
The greater the accessibility of light the greater the success of a plant
Plants evolve to grow successfully - in areas of low light intensity plants have larger leaves
How does temperature (abiotic factor) affect communities
Temperatures greatest effect is on the enzymes which control metabolic reactions
In warmer climates plants develop more rapidly as their metabolisms are faster.
This also affects cold blooded animals like lizards who need the sun to warm them up
How do moisture levels (abiotic factor) affect communities
For most plant and animal species, a lack of water leads to death
(Emg water is the main component in blood plasma)
Water is needed to maintain turgor pressure in plants and for photosynthesis
How does soil pH (abiotic factor) affect communities
The pH of a soil affects the minerals it contains.
Some plants grow better in acidic soil such as ferns
Some plants grow better in alkaline soils such as cucumbers
What do plants need to survive
Light
Water
Carbon dioxide
Minerals
Space
What do animals need to survive
Food
Water
Breeding partners
Space (territory)
Shelter
What is competition
When two or more organisms are contesting for a resource
What are the main relationships between species in a community
There are three main ecological relationships between organisms
Predations mutualism and parasitism
What is interdependence
How different organisms depend on each other within a community
What is predation
A predator - prey relationship
The size of the predator population directly affects the size of the prey population
Mutualism
A relationship where both organisms benefit
E.g oxpeckers (small birds) eat the ticks and fleas living on buffalos skin
They gain food and free the buffalo from irritation and disease
Parasitism
A parasitic relationship
Only one organism (the parasite) gains, while the organisms it lives of (host) suffers
E.g tapeworms in a digestive system
What is a pyramid of biomass
A pyramid showing the transfer of biomass between organisms.
As the trophic level increases the size of animals increases but the number of them decreases.
This means the biomass decreases going up the pyramid
What is a pyramid of numbers
A pyramid that shows the number of organisms at each trophic level.
This doesnt always look like a traditional pyramid
E.g 1 oak tree is eaten by 2000 caterpillars.
(This is known as an inverted pyramid)
Why are pyramids of biomass rarely inverted
As the biomass is plotted.
Both number and size of organisms is taken into account
How do you calculate biomass
The average biomass of an organism is calculated then multiplied by the number of organisms.
How do you measure biomass
You need to calculate the ‘dry mass’ as water can vary between individuals
This is done by killing the organism and drying it in a kiln
How do you draw a pyramid of biomass
Take the biomass of each organism and divide it by a sensible scale factor (e.g 1cm = 10kg) then draw each trophic level and label them
Try to place each new level in the center of the previous one
What percentage of sunlight energy does each plant transfer into food
Producers only transfer around 1% of energy from the sunlight into food stores
This happens due to limiting factors in photosynthesis
Why does biomass decrease at each trophic level
Plants use half of their energy in increasing biomass and respiration
Consumers will then eat the plant and absorb its biomass, however not all of its biomass will be absorbed as often the whole organism is not eaten (emg the roots)
Consumers will convert 10% of the energy into mass
Consumers lose energy in transportation
They lose biomass in excretion and egestion
Biomass is also lost when energy is used for movement and growth
Not all organisms are eaten so energy is lost there as well
What is egestion
Removal of indigestible waste from an organism
What is excretion
Removal of waste metabolic products from an organism
How do you calculate the efficiency of biomass transfer
(Biomass available after the transfer ÷ biomass available before the transfer) ×100
Why do food chains have a limited number of trophic levels
As eventually the transfer of energy becomes so low not enough energy can be transferred to sustain a life process
What is nutrient cycling
The process of nutrients being moved around an ecosystem through biotic and abiotic components
What are the main processes in the water cycle
Evaporation - the sun heats water turning it into water vapour
Condensation - As the water vapour begins to cool it condenses back into water forming clouds
Precipitation - water falls as rain, snow or hail when the water droplets get larger
Percolation - water falls through gaps in soils and rocks
Transpiration - loss of eater vapour from the plants to the atmosphere
Surface run-off - water that isn’t absorbed into the soil (soil is saturated) runs off into the nearest body of water
What does interspecific mean
Competition between different species
What does intraspecific mean
Competition between organisms in the same species
What is commensalism
Where one organism benefits and the other is neutral
What is a symbiotic relationship
A long term interaction between two different species
Describe the process of the nitrogen cycle
Nitrogen - fixing bacteria in the roots convert nitrogen in the atmosphere into ammonia
Nitrifying bacteria convert the ammonia into nitrites the nitrates (nitrogen fixation)
Plants now absorb nitrates through the roots where its transported by the xylem to the rest of the plant (assimilation)
Nitates in the soil may be converted back to a gas by denitrifying bacteria (denitrification)
Animals gain nitrogen when they eat plants and when the die decomposers break them down into the soil(or there waste) (then nitrification happens)
What is the carbon cycle
A process by witch carbon is recycled through the atmosphere
How is carbon removed from the atmosphere
It is removed by the plants (e.g algae) during photosynthesis to create glucose
How is carbon transferred between organisms / into the soil
When animals eat plants some carbon is transferred, through proteins and carbohydrates
Carbon is also taken into the soil after decomposition
Over millions of years plants and animals break down to make fossils
How is carbon released back into the atmosphere
Respiration - by plants an animals carbon dioxide is released
Decomposition - Decomposers also respire while breaking down plants and animals
Burning fossil fuels - when fossil fuels are burnt the naturally trapped carbon is released into the atmosphere
What factors affect the rate of decomposition
Temperature - higher temps prevent decomposition as enzymes used denature + results in the death if the microorganism
Moist environments - if not enough water is available reactions in the microorganism will slow down or be prevented. This stops the rate of decomposition
Aerobic conditions - Oxygen is needed for the microorganisms to respire.
If there is no oxygen there will be no decomposition as the microorganisms cant survive
How to calculate rate of decay
Rate of decay = change in mass (g) / time (day)
What are the most common decomposers
Bacteria fungi
What are detritivores
Small animals which shred organic material into smaller pieces
This speeds up the rate of decomposition as the surface area to volume ratio is greater.
E.g worms
How do fungi release nutrients into the soil
They release enzymes that break down organic matter.
They can then absorb SOLUBLE nutrients into their bodies and use them for growth and as an energy store
Bacteria and fungi can be eaten by other organisms resulting in the nutrients being passed on
Some of the nutrients they break down are directly released into the soil / environment (if not absorbed)
What is an organic compound
A compound containing both carbon and hydrogen
Where can nitrifying bacteria be found
In the root nodules of legumes
(Plants such as peas pr lentils)
What is the difference between a habitat and an ecosystem
Habitat is the natural environment in which a specific organism lives
Ecosystems are the relationships between the biotic and abiotic components of the environment
