unit 3 - life on earth Flashcards
3 ways energy is lost during energy transfer?
movement, heat, undigested materials
what does a pyramid of numbers show?
it shows the population of each organism in a food chain
What does a pyramid of energy show?
it shows the amount of energy at each stage in each organism in the food chain
what pyramid can have an irregular shape?
pyramid of numbers
why would a pyramid of numbers have an irregular shape?
it would have an irregular shape if a tree/bush/singular plant is the producer or if parasites feed off the top predator
what do the arrows in a food web show?
the flow/direction/change in energy between organisms
what is an advantage of a shorter food chain?
Less energy will have been lost by the time it gets to the top predator, so the predator gets a good amount of energy
species definition
a group of organisms which can interbreed to produce fertile offspring e.g. homosapiens
habitat def.
the place an organism lives e.g. caterpillars on a leaf
population def.
a group of organisms from the same species e.g. a group of caterpillars
community def.
all the population living in the ecosystem e.g. grass, ladybirds etc.
producers def.
organisms that use the sun to produce food by the process of photosynthesis e.g. all green plants
consumers def.
organisms that obtain energy through eating other organisms e.g. carnivores, omnivores, herbavores
herbivore def.
an organism that only feeds on plant material. e.g. cow, rabbit
carnivore def.
an organism that feeds on solely animal material. e.g. wolves, cats
omnivore def.
an organism that feeds on both plant and animal material e.g. bears, pigs
decomposer def.
an organism that breaks down organic material (dead bodies, waste) e.g. fungi, mould
ecosystem def.
The balance of all living and non living parts of a biological unit e.g. oak tree, pond
what is a biotic factor?
a living factor that can affect organisms in an ecosystem e.g. predators, disease, competition
what is an abiotic factor?
a non living factor that can affect the organisms in an ecosystem e.g. temperature, light, pH.
predator Def.
an organism which hunts other organisms e.g. owl, eagle
prey Def.
an organism which is hunted e.g. mice, rabbit
how much energy is lost at each stage in the food chain?
90%
what can energy be stored in?
undigested materials
when does competition occur?
when resources are in short supply
what are the two types of competition?
interspecific and intraspecific
what is intraspecific competition?
when individuals of the same species compete for the same resources in an ecosystem
what is interspecific competition?
when individuals of the same species compete for the same/similar resources
what type of competition is more intense and why?
intraspecific is more intense as they are competing for the exact same resources
state some resources organisms compete for?
land, water, food, territory, light, root space
list some abiotic factors?
pH, light intensity, temperature, moisture
list some biotic factors?
disease, predation, food availability, grazing
what is an indicator species?
an indicator species is an organism that serves as a measure of the environmental conditions that exist in a given locale by its absence or presence
what does light intensity effect?
it effects the growth of photosynthesizing plants
what is the effect of pollution?
it can be toxic and kill species in that area
what is the effect of deforestation?
it destroys organisms habitats, making the organisms extinct
list some ways of minimizing errors when using a pitfall trap?
set up multiple traps, make sure trap is level with ground, check regularly for organisms, have drainage holes
list some ways of minimizing errors when using a quadrat?
make sure to throw randomly, make sure they are spread out, count the plants carefully
list some ways of minimizing errors when using a pH meter?
wipe probe between uses, sample more than one area
list some ways of minimizing errors when using a light meter?
don’t shadow the meter, make sure weather conditions are normal for the area you are sampling, dont place the meter in the shade if that is not the normal condition for the area
niche Def.
the role an organism plays in the community
what is a light meter used for!
it is used to measure the light intensity in a certain area
what is a pH meter used for?
it is used to measure the soils pH levels in a given locale
what is a moisture meter used for?
it is used to measure the soil moisture levels in a given locale
what is a quadrat?
used to sample plants. should be thrown randomly and repeated several times
what is a pitfall trap?
used to sample small insects by being placed in the ground. should be level with ground and checked regularly for insects.
what chemicals are used to increase food yeild?
fertilisers and pesticides
what are pesticides used for?
they are used to kill harmful pests that reduce crop yield.
what are fertilisers used for?
they are used to increase crop yield by adding nitrates.
nitrates?? sorry ladies idk how to words this
nitrates are dissolved in soil water and are absorbed into plants
nitrates are used to produce amino acids which are synthesized into plant proteins
what happens when fertilisers leach into water?
this adds extra unwanted nitrates, this therefore increases the algae populations causing algal blooms.
these algal blooms block off light to aquatic plants. these plants die.
the dead plants and algae become food for the bacteria which increase in numbers due to this.
the bacteria uses up large quantities of oxygen, reducing the oxygen levels for other aquatic species, causing them to die
what is bioaccumulation?
it is the gradual build up of substances such as pesticides or other chemicals in an organism/food chain. the chemical is passed along the food chain and can build up to lethal levels.
what are 2 alternatives to pesticides and fertilizers?
GM - gmed crops means that instead of spraying crops with fertilisers as they can produce it themselves (changes the genome) (idk what this means ladies all I know is that I wrote this down for the last test)
Biological control - this is the control of a pest by the introduction of a natural predator or parasite of the pest
what are nitrates?
chemical found in fertilisers which dissolves in soil water and is absorbed in plants
what are amino acids?
chemicals which plants make from nitrogen. these can be used to synthesise protiens.
algal bloom Def.
the rapid growth of algae due to excessive nitrates leaching into water
bioaccumulation Def.
the build up of toxic substances in living organisms
biological control Def.
the use of a natural predator to kill pests on crops
what are genetically modified crops?
crops which have altered genetic material to have improved yield. used to reduce the use of fertilisers.
speciation Def.
speciation is the evolution of two or more species from one original ancestor.
what are the stages of speciation?
isolation, mutation, natural selection, speciation.
describe the speciation stages?
the population becomes ISOLATED by a barrier, different MUTATIONS occur in each sub-population, NATURAL SELECTION selects for different mutations in each group, each sub-population until they become so genetically different that they are 2 different species
what are the types of isolation barriers?
geographical (rivers, mountains)
ecological (pH, salinity)
behavioural (fertility windows)
what is an adaptation?
an adaptation is a feature of an organism which helps them to survive
what are two environmental factors which can increase the rate of new alleles produced by mutation?
UV radiation and chemicals e.g. bromine
what is natural selection?
natural selection also known as ‘survival of the fittest’ occurs when there are selection pressures. the best adapted individuals survive to reproduce, passing the new alleles onto the next generation which now have that selective advantage
mutation Def.
a random change in as organisms DNA. the only source of new alleles. These can be beneficial, have no effect, or harmful towards the species
natural selection Def.
exists in members of a sexually reproducing population. this allows a population to evolve over time in response to changing environmental conditions
what is variation?
variation occurs when there are selection pressures on a population. the best adapted individuals survive to reproduce and pass on the favourable alleles to the next gen.
what is an allele?
a variation of a gene
