unit 3 Flashcards
what is an ecosystem
consists of all the organisms (the community) living in a particular habitat and the non-living components with which they interact
what is a species
group of organisms which can interbreed to produce fertile offspring
what is a population?
number of organisms within a particular species
what is biodiversity
variety of life within an ecosystem
what is a community?
all the organisms that live within a habitat or ecosystem
what is a habitat
the place where an organism lives
what is a food chain
a series of organisms which can depend on each other for food (energy)
what’s a herbivore?
an animal which consumes only plants to gain energy
what’s a omnivore?
an animal that consumes both plants and animals to gain energy
what’s a carnivore
an animal that consumes other animals to gain energy
producer:
any green plant that makes its own food via photosynthesis
consumer:
an animal that consumes plants or other animals for energy
prey:
animals who are hunted by predators
predator:
hunts prey to gain energy
food web:
a diagram which shows the interconnection of food chains and the feeding relationship in an ecosystem
niche:
role an organism plays within its community
interspecific competition:
individuals of different species competing for one or a few resources they require
intraspecific competition:
individuals of the same species and is for all resources required
biotic:
living factor which affects biodiversity
eg competition, predation, grazing, disease
abiotic:
non-living factor which affects biodiversity
eg temperature, pH, soil moisture, light intensity
quadrats:
used to estimate the number of plants or slow moving animals of a particular type in an area
errors of quadrats and how to minimise
not enough placed - place more
some plants may be partially in or out - decide how ur going to sample
biased - throw randomly
pitfall traps:
use to sample invertebrates which live on the ground
errors of pitfall traps and how to minimise
not enough to represent ecosystem - place more traps
some animals eaten by predators - check regularly
water filling in trap - drainage holes
indicator species:
species that by their presence or absence indicate environmental quality/levels of pollution
how is energy lost in a food chain
- heat
- undigested materials
- movement
pyramid of energy
shows the energy available at each link in food chain
pyramid of numbers
diagram that shows the total number of organisms at each link in food chain
photosynthesis:
reaction that converts light energy into chemical energy. during photosynthesis light energy along with carbon dioxide and water are used to produce sugar and oxygen
word equation:
light energy
CO2 + H2O —————-> sugar + O2
light reactions:
light energy from the sun is trapped by a green pigment called chlorophyll in the chloroplast. the light energy is converted into chemical energy which generates ATP. water is split into hydrogen and oxygen during the light reactions. the hydrogen is used in the second stage and the oxygen diffuses from the cell
carbon fixation:
CF uses hydrogen and ATP from the 1st stage to convert carbon dioxide form the air into sugar. this stage is catalysed by enzymes : affected by temp
fates:
- sugar converts into starch (storage)
- sugar converts into cellulose ( structural)
- sugar is available for respiration (glucose)
limiting factors of photosynthesis
- temp
- light intensity
- carbon dioxide concentration
fertiliser:
added to soil to increase nitrate content of soil to increase crop yield
what is GM crops
involves inserting DNA into the genome of an organism to give it new or different characteristics
helps to maintain crop yield
bioaccumulation:
the build up of toxic substances in living organisms
pesticide:
substance used to kill insects which destroy the crop
biological control:
controlling pest numbers by introducing a natural predator
mutation:
random change to genetic material, they can be neutral, advantageous or disadvantageous to survive
- mutations are spontaneous and are the only source of new alleles
mutagenic agent:
environmental factors which increase the rate of mutation eg extreme temp, radiation and chemicals
adaptation:
inherited characteristic that makes an animal/plant well suited to its environment
variation within a population makes it possible for…
… a population to evolve over time in response to changing environmental conditions
selection pressures of natural selection:
food
predation
climate
disease
natural selection:
- species produce more offspring than the environment can sustain
- when there are selection pressures, the best adapted individuals survive to reproduce, passing on the favourable alleles that confer the selective advantage
- these alleles increase in frequency within the population
- this can result in a population becoming better adapted to its ecological niche
speciation (simple definition)
formation of a new species
isolation barriers:
- geographical barriers = physically separating groups within a population eg rivers or mountains
- behavioural barriers = separating populations because of behaviour of individuals eg females selecting for a different male characteristic during mating season
- ecological barriers = separating populations due local differences in the environment eg pH or salinity
stages of speciation:
- isolation by barrier - speciation occurs after part of a population becomes isolated by an isolation barrier (ecological, behavioural or geographical)
- different mutations occur randomly in the each sub population causing new variation
- natural selection selects for different mutations in each group, due to different selection pressures
- each sub-population evolves until they become so genetically different that they are 2 different species (they can’t interbreed and produce fertile offspring)
why can’t photosynthesis occur at very high temps?
because enzyme activity is lower
what are nitrates?
they are the type of chemical found in fertilisers that plants use to make amino acids
speciation (simple steps)
- isolation barriers
- mutations in each sub-population
- natural selection
- evolve into different species
why does natural selection ensure the most favourable alleles are passed on?
because the species with the favourable alleles survive as they are more adapted
products of light reactions:
hydrogen and oxygen
