adaptation, interdependence and competition

• the habitat is the environment in which an organism lives e.g. elephants habitat is in the grasslands
• a population is the total number of organisms of the same species living in the same geographical area.
• a community is the populations of all the different species that all live in the same habitat.
• biotic means living and abiotic means non-living.
• the abiotic parts of an environment include water and the minerals in the soil
• an ecosystem is both the biotic and abiotic parts of an environment and how they interact.
• living organisms require a supply of materials from their surroundings e.g. water. they can also get materials from other living organisms.
• resources that animals need in an environment are often in short supply, meaning that organisms have to compete with each other.
• plants compete with each other for light and space as well as water and mineral ions in the soil
• animals compete with each other for food and water as well as mating partners and territory
• every animal depends on other living organisms for food, we call this interdependence. e.g. lions eats zebras and zebras eat plants. living organisms also rely on each other for shelter, e.g. sheep could rely on trees for shelter. plants can also depend on animals e.g. many plants depend upon bees to spread their pollen
• if a species disappears from a community, this could affect the whole community.
• a stable community is one where the populations of the species inside remain constant. populations of organisms are in balance.
• a biotic factor is the availability of food. all animals eat other living organisms, however all sources of food are biotic factors and if the availability of food falls, the number of organisms in the community will also fall.
• a biotic factor is the arrival of a new predator. this can cause the population of a prey species to fall and could also cause other predators to be affected if they are competing for the same prey.
• a biotic factor is competition between species. if a species is outcompeted then its population will fall to extinction or so low that there are no longer sufficient numbers to breed.
• a biotic factor is new pathogens. if an infectious disease emerges and then spreads, it can wipe out a population of a species.
• an abiotic factor is light intensity. all plants need light, however if light intensity is too low, the rate of photosynthesis falls and plants will grow more slowly. this can impact a community because animals that feed on plants may not have enough food
• an abiotic factor is temperature. if the temperature of an environment changes this could cause the distribution of species to change (animals may migrate away).
• an abiotic factor is water. both plants and animals need water for survival, many species are adapted to deal with low levels of water.
• the pH and mineral content of the soil is an abiotic factor. many plants cannot grow on soil that is too acidic or too alkaline. plants also need certain minerals in the soil e.g. nitrate which is used to make amino acids for proteins.
• the wind intensity and direction is an abiotic factor affecting plants. e.g. strong winds blowing inland from the sea can cause plants to lose water. so plants growing in sand dunes are often adapted to reduce water loss
• abiotic factors also include carbon dioxide and oxygen. carbon dioxide is needed for plants to photosynthesise, if carbon dioxide levels fall then the rate of photsynthesis will also decrease. oxygen is needed for aerobic respiration. the level of oxygen in the air stays quite constant, however dissolved oxygen in water can fall e.g. on hot days. this can be harmful to aquatic organisms like fish
• structural adaptations are adaptations of body shape or body structure. functional adaptations are adaptations to the body functions of an organism. behavioural adaptations are adaptations to the animals lifestyle or behaviour
• functional adaptations of camels include

  • concentrated urine
  • dry faeces (both reducing water loss)
  • can tolerate large changes in body temperature
• an example of behavioural adaptations include being nocternal or living in certain places to avoid predators
• animals that live in cold places have structural adaptations like

  • very thick fur - providing insulation and reducing heat loss to air
  • fur on soles of feet - reducing heat loss to ice and snow
  • small ears - reducing surface area
  • camoflauge - stop being hunted by predators and be able to hunt its prey
• cactus are adapted to dry conditions. most plants lose their water through leaves but cacti have very small leaves or only spines. they have extensive and shallow roots, allowing them to catch water after rainfall before it evaporates. they can also store water in their stem
• extremophiles are organisms adapted to live in very extreme conditions. e.g. bacterias. as well as high pressures and temperatures, extremophiles can also live in very high concentrations of salt
• an example of a food chain is grass, rabbits then foxes
• food chains usually begin with a green plant. these are called producers. they are very important because they synthesise complex molecules e.g. glucose. glucose is an example of biomass which will now be passed down the food chain
• biomass passes down the food chain. producers are the source of all biomass in a community, hence why they are so important. biomass is matter from living organisms
• organisms that eat producers are called primary consumers.
• primary consumers are eaten my secondary consumers
• secondary consumers are eaten by tertiary consumers
• consumers that kill and eat other animals are called predators. the animal being eaten is called the prey
• when population of predator decreases, the population of prey increases and vice versa
• the numbers of predators and prey rise and fall in cycles. this is only true in a stable community
• random sampling is used to compare the numbers of organisms in different areas. we use a quadrat to do this. to use a quadrat, we place the quadrat down and count the number of organisms inside the quadrat. this can be used to sample plants, or slow-moving animals.
• we can also sample along a transect. we do this if we want to investigate whether the number of species change as we move across a habitat. a transect is simply a line we measure along. we use a quadrat to count the number organisms at intervals along a transect.