IB Biology - 4.1: Species, Communities and Ecosystems

what is an example of the interdependence of living organisms?

when Mount Saint Helens erupted and covered areas with hot ash, and ecosystems were destroyed, however within months small plants and animals reappeared

what is a species?

a group of organisms that can interbreed and produce fertile offspring

what do members of a species have in common?

they have similar physical characteristics, have different gene pools to other organisms and have a common phylogeny

what are some exceptions to rules of species?

some members of separate species can interbreed, and some of the same species don't interbreed. Some organisms also produce asexually

what are hybrids?

they are the offspring of two similar but different species, however most offspring will be infertile. example: zorse

what is population isolation?

it is when groups of species that are separated for long periods of time evolve differently because they end up occupying different environments

what are some causes of population isolation?

this can cause members of the same species to differentiate to an extent where they are no longer to reproduce with each other due to different gene pools

what are autotrophs?

also known as producers, they synthesise organic molecules from inorganic molecules through e.g photosynthesis

what are some examples of autotrophs?

plants, algae and some bacteria

what are heterotrophs?

they must obtain organic molecules from other organisms through eating/ingesting them. they eat autotrophs. also known as consumers

what are some examples of heterotrophs?

animals, fungi and some bacteria

what do consumers consume?

may consume producers and their products OR may consume other consumers and their products

what are detritivores?

they eat non-living organic matter like dead leaves, faces and carcasses, they are also a type of consumer. they are internal digesters

what are saprotrophs?

they are a type of consumer, they digest their food externally, meaning they secrete digestive enzymes onto either living or dead organic matter

why are saprotrophs and detritivores important?

they are very important as they recycle nutrients. when they decompose dead things, the nutrients stuck in those dead organisms become available for other organisms to use

what is a population?

a group of same species living in the same area

what is a community?

a group of populations living and interacting with each other in the same area

what is an ecosystem?

all biotic and abiotic factors in a given area

what are abiotic factors?

they are components of the environment that are non-living, such as pH, temperature, light levels, moisture levels, rocks and clouds

what are biotic factors?

they are components of the environment that are living, such as plants, animals and bacteria

where do autotrophs get their nutrients?

they get them from photosynthesis, where they make organic compounds from inorganic compounds such as CO2 and water

what is nutrient cycling?

unlike how heat flows through the system that is our earth, the amount of matter (nutrients) stays constant. Nutrients is recycled instead

what are decomposers?

they include saprotrophs and detritivores who unlock nutrients stuck in dead bodies of organisms to allow them to return to the soil to be accessed

what is the cycle of the sustainability of ecosystems?

1. producers photosynthesis making organic compounds
2. consumers eat producers
3. complex molecules are digested by consumers
4. consumers die, allowing their cells to be broken down by decomposers
5. nutrients are then returned to the soil