Unit 4: Organisms and their environment Flashcards
Use these notes: https://drive.google.com/drive/u/0/folders/1HIVIzsEmLmZsSA1jHISve4pUfhdQVv4Z
The sun is the…
principal source of energy input to biological systems.
Define Food chain
Define food chain as showing the transfer of energy
from one organism to the next, beginning with a
producer
Define food web
Define food web as a network of interconnected food
chains
Define producer
Define producer as an organism that makes its own
organic nutrients, usually using energy from
sunlight, through photosynthesis
Define consumer
Define consumer as an organism that gets its energy
by feeding on other organisms
Define herbivore
Define herbivore as an animal that gets its energy by
eating plants
Define carnivore
Define carnivore as an animal that gets its energy by
eating other animals
Define decomposer
Define decomposer as an organism that gets its energy
from dead or waste organic matter.
Define ecosystem
Define ecosystem as a unit containing all of the
organisms and their environment, interacting
together, in a given area, e.g. a lake
Define trophic level
Define trophic level as the position of an
organism in a food chain or food web
Describe how energy is transferred between
trophic levels.
In order for the energy to be transferred it first needs to be consumed. Between each trophic level only 10% of the energy in the previous trophic level is passed on. A lot of the energy loss comes from:
making waste products eg (urine) that get removed from the organism
as movement
as heat (in mammals and birds that maintain a constant body temperature)
as undigested waste (faeces) that is removed from the body and provides food for decomposers
Explain why food chains usually have fewer than
five trophic levels
Remember from the notes
Identify producers, primary consumers, secondary
consumers, tertiary consumers and quaternary
consumers as the trophic levels in food webs and
food chains.
do it.
Construct simple food chains.
do it.
Interpret food chains and food webs in terms of
identifying producers and consumers.
do it.
State that consumers may be classed as primary,
secondary and tertiary according to their position
in a food chain.
do it.
Describe the carbon cycle, limited to
photosynthesis, respiration, feeding,
decomposition, fossilisation and combustion.
Seethisvideo:https://www.youtube.com/watch?v=cWj3u8voDSg
Discuss the effects of the combustion of fossil
fuels and the cutting down of forests on the
oxygen and carbon dioxide concentrations in the
atmosphere
Explain the undesirable effects of deforestation on
the environment.
List the undesirable effects of deforestation as an
example of habitat destruction, to include
extinction, loss of soil, flooding, and increase of
carbon dioxide in the atmosphere.
State the sources and effects of pollution of water
(rivers, lakes and the sea) by chemical waste,
discarded rubbish, untreated sewage and
fertilisers.
Explain the process of eutrophication of water in
terms of:
ー increased availability of nitrate and other
ions
ー increased growth of producers
ー increased decomposition after death of
producers
ー increased aerobic respiration by
decomposers
ー reduction in dissolved oxygen
ー death of organisms requiring dissolved
oxygen in water.
Explain everything you know about acid rain:
https://www.youtube.com/watch?v=KEAfip6F3-8
something that isn’t mentioned in the video:
rain is naturally a bit acidic due to CO2 in the atmosphere forming carbonic acid in rain
Define population
a group of organisms of the same species living in the same habitat at the same time.
Define community
the population of all the animals, plants and microorganisms that are found in a particular habitat.
Define omnivore
An organism which may feed on both animals and plants
What is biomass?
the mass of living material in a given area.
e.g. less energy is transferred at each level of the food chain so the biomass gets smaller
What is a key thing you should remember when asked to draw a food chain?
ARROWS, it has to have ARROWS
Explain why the population of a predator is much smaller than its prey:
(1) Inefficient energy transfer through the trophic levels - you have to say INEFFICIENT/only 10% of energy is transferred at each level
(2) Describe processes where the energy is lost at each trophic level (e.g. respiration, faeces, etc)
(3) If they’ve asked you to talk about a specific animal in a food chain mention its POSITION in the food chain e.g. is it the primary/secondary consumer?
