biodiversity & distribution of organisms ( key areas 1&2) Flashcards
what is the meaning of biodiversity?
The range (variety/number) of species within an ecosystem.
what is a species?
A group of organisms which can interbreed and produce fertile offspring.
state the definition of a population.
The total number of living organisms of one type (species) living in a habitat.
state the definition of a biotic factor
BIOTIC factors are living things that affect the distribution of organisms e.g., competition for resources, grazing, predation, food availability, and disease.
state the definition of competition
Competition is the struggle between individuals when resources are in short supply / limited e.g. food, light, water etc. The effects of competition include the more successful species increasing in number and less successful species decreasing in number.
state the definition of a habitat.
The place where an organism lives e.g. in water, in soil, trees etc.
state the definition of a community.
All the organisms (e.g. plants, animals and micro-organisms) that live in a particular area.
state the definition of an ecosystem.
All the organisms (the community) living in a particular habitat and the non-living components with which the organisms interact.
Sometimes written as: Community + habitat
name the 2 different types of competition
interspecific
intraspecific
what is a producer?
a producer makes their own food by photosynthesis
what is a consumer?
a consumer is an animal which eats other organisms
what is a predator?
A predator is an animal that hunts and eats other animals
what is a prey?
prey is an animal that is hunted and eaten by other animals
what is a herbivore?
a herbivore is an animal which eats only plants
what is an omnivore?
an omnivore is an animal which eats plants and animals
what is a carnivore?
a carnivore is an animal which eats only animals
what is a decomposer?
A decomposer is an organism which feeds on dead organisms.
what do the arrows in a food chain represent?
they represent the direction of energy flow
which human activities can disrupt a food web?
hunting, fishing, using chemicals that cause pollution
what is interspecific competition?
interspecific - competition which occurs amongst different species for one or a few of the resources they require
what is intraspecific competition?
intraspecific - competition which occurs amongst individuals of the same species for all resources required, intraspecific competition is more intense than interspecific
state the meaning of an ABIOTIC factor
ABIOTIC factors are non - living things that affect the distribution of organisms e.g. temperature, pH, light intensity and humidity
what happens at low levels of grazing?
at low levels of grazing slow growing species will die as they are out competed for resources by faster growing species
what happens at intermediate levels of grazing?
at intermediate levels of grazing some of the faster growing species are eaten so as a result the slower growing species are able to survive therefore increasing biodiversity
what happens at high levels of grazing
at high levels of grazing damage is caused to majority of species surviving therefore decreases biodiversity as most species die
what are the 5 ABIOTIC factors affecting an organisms distribution?
pH, temperature, light intensity, humidity, soil moisture
what source of error can occur whilst using a light meter and how would you overcome it?
casting a shadow over the light meter, to overcome this error do not stand between the sun and the light meter
what source of error could occur whilst using a pH meter or soil moisture meter and how can it be overcome?
moisture from previous reading left on the probe, to overcome this error wipe the probe dry between measurments
name 4 sampling methods
quadrat ( line transect) , pitfall trap, tree beating, tullgren funnel
how can sampling results be more reliable?
Replication if sampling should be taken to provide more accurate results.
name 5 human threats to biodiversity
Overexploitation, pollution, invasive species, climate change, land and water use change
what is a niche?
A niche is the role that an organism plays within a community. It relates to the resources it requires in its ecosystem and its interaction with other organisms in the community. It involves competition and predation and the conditions it can tolerate
when does competition occur?
Competition in ecosystems occurs when resources are in short supply
interpretation of predator prey interaction graphs
- at low population the predators always lacks behind the population of prey
- at higher prey populations the predators will find more prey, eat them and the prey population will decrease
- because they have eaten more the predator population can reproduce more and their numbers increase.
- lower prey populations limit how many prey can be found and eaten by predators so predator numbers will decrease
can predation affect biodiversity?
predation can increase biodiversity
what are sampling techniques used for?
- to find out which plants and animals live in an ecosystem
- to find out how common/ rare plants and animals are in a given ecosystem
- to investigate the reasons why plants and animals live there
what is a source of error for a pitfall trap and quadrat( measuring biotic factors) and how can they be fixed?
both - the numbers and types of organism may not represent the whole ecosystem ( take several samples to make results more reliable)
pitfall trap - trapped organisms may be eaten by birds ( cover the trap with a raised stone or leaf)
what is a paired statement key?
A paired statement key is made up of pairs of statements to help identify an organism
what is an indicator species?
Indicator species are species that by their presence or absence indicate environmental quality/ levels of pollution. Lichens are often used as indicators of air pollution.
describe the 3 types of lichen and what they can tolerate
crusty lichen can tolerate high levels of sulphur dioxide, leafy lichen can tolerate moderate levels and hairy lichen can not tolerate Sulphur dioxide at all.
Aquatic invertebrate indicator species
Invertebrate species in water tend to be used as an indicator species to determine the quality of water by their presence or absence
Aquatic invertebrate indicator species
Invertebrate species in water tend to be used as an indicator species to determine the quality of water by their presence or absence
why can deforestation impact biodiversity ?
why can deforestation impact biodiversity ?
why can deforestation ( biotic factor) impact biodiversity ?
when forests are cleared many animals may lose their habitats and or food source. Many plants and animal species are lost forever.
what is a food chain?
A food chain is a diagram which shows a simple feeding relationship between organisms
