classification

organism - a living thing

classification - an organisation of living things (organisms) into groups according to their similarities

unicellular - living thing that consists of a simple cell

multicellular - living thing made up of many cells

the first two kingdoms linneas suggested where animalia and plantae

the microscope meant scientists discovered lots more living things

the six kingdoms of life scientists use to classify living things are:

archaea

• microscopic

• unicellular

• often live in extreme enviroments

bacteria

• microscopic

• unicellular

• no seperate nucleus

animalia

• multicellular

• cells have a nucleus

• move freely

• get energy from consuming other organisms

plantae

• multicellular

• cells have a nucleus

• cannot move freely

• uses energy from the sun to make sugars

fungi

• multicellular

• cannot move freely

• absorb nutrients from other organisms

protista

• most are unicellular

• cells have a nucleus

• eg. amoeba and algae

reptiles - lay leathery eggs, dry scales

fish - lay eggs in water, wet scales, breathe through gills

amphibians - moist skin, lay jelly coated eggs in water

birds - lay hard shelled eggs, have feathers

mammals - give birth to live young, produce milk (mammary glands), have hair

organisms, populations, and habitats

ecology - study of the interactions of living organisms with each other and their environment

organism - one individual, a single living thing

population - a group of interbreeding organisms living in the same area

community - all the organisms, all types, living in the same area

ecosystem - all the organisms, living in the same area and their non-living environment

habitat - the place where an organism lives, has all of the things an organism needs to survive eg. right amount of water, light, and oxygen

food chains and food webs

producers - organisms that make their own food through photosynthesis eg. trees and algae

consumers - organisms that eat producers or other consumers eg. grasshoppers and rabbits

herbivores - animals that only eat plants eg. cows and elephants

carnivores - animals that only eat other animals eg. wolves and lions

omnivores - animals that eat both plants and animals eg. chimpanzee and racoon

decomposers - organisms that feed off other dead organisms eg. slugs and beetles

food chain - diagram that shows what an organism eats

food webs - a combination of all the food chains in a particular community

each step in a food chain is called a trophic level

fox - tertiary consumer

hedgehog - secondary consumer

caterpillar - primary consumer

lettuce - producer

pyramids

biomass - mass of living organisms found in each level of the food chain, calculated by multiplying average mass of organism by total number of organisms

pyramids of numbers

in a pyramid of numbers the length of each bar represents the number of organisms at each level in the food chain

a single tree can support many organisms

pyramids of biomass

in a pyramid of biomass the length of each bar represents the biomass at each level of the food chain

at each level, the amount of biomass and energy available is reduced, giving us a pyramid shape

most food chains are rarely more than 3 or 4 levels, why?

• too much energy loss

• not enough food for higher levels

• energy’s released through keeping warm and waste

• small amount used for growth and biomass

competition and limiting factors

limiting factor - anything that reduces the size of a population

animals main limiting factors:

resources

• food

• space

• water

• mates

other factors

• being eaten (preditation)

• competition

• disease

competition - occurs when two organisms are in need of the same resources

plants main limiting factors:

resources

• light

• space

• water

• soil minerals

other factors

• being eaten (grazing)

• competition

• disease

types of competition

interspecific - between members of different species

intraspecific - between members of the same species

predator-prey relationships

all organisms have adaptations that increase their chances of survival and reproduction

• physical

  • eg. camouflage

• behavioural

  • eg. walking stealthily

human impact on the environment

pest - any destructive organism that attacks crops, food, livestock, etc.

pesticides kill pests that would otherwise damage crops, reducing yield and profit

they break down and become harmless over time, OR are persistent and not broken down

they dont break down well in the environment

bioaccumulation refers to the accumulation of substances such as persistent pesticides or other chemicals in an organism

the high up the food change an organism is found, the greater amount of bioaccumulation

indicator species - used to assess the overall health of an ecosystem by looking at their presence, absence or abundance. it can reflect the levels of pollution

lichens are plants that grow on exposed places such as rocks or tree bark

they need to be very good at absorbing water and nutrients to grow

rain water contains just enough of these to keep them alive

because they are so sensitive, air pollution such as sulphur dioxide dissolved in rain water stops them from growing