19 organisms and their environment Flashcards
What is the principle source of energy to biological systems?
The sun is the principle source of energy input to biological systems
Describe the flow of energy through living organisms, including light energy from the Sun and chemical energy in organisms, and its eventual transfer to the environment
- Energy flows from the sun to the first trophic level (producers) in the form of light
- Producers convert light energy into chemical energy and it flows in this form from one consumer to the next
- Eventually all energy is transferred to the environment
– Energy is passed on from one level to the next with some being used and lost at each stage
food chain
showing the transfer of energy from one organism to the next, beginning with a producer
food web
a network of interconnected food chains
producer
an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
consumer
an organism that gets its energy by feeding on other organisms
herbivore
an animal that gets its energy by eating plants
carnivore
an animal that gets its energy by eating other animals
decomposer
an organism that gets its energy from dead or waste organic material
Advantages of using a biomass pyramid rather than a number of species pyramid
more accurate as it takes the organisms size/mass into account
trophic level
the position of an organism in a food chain, food web or ecological pyramid
How is energy lost from one trophic level to the next?
Energy is lost as metabolic heat. It is used for: muscle contractions, maintaining body temperatures, movement, excretion, egestion.
Explain, in terms of energy loss, why food chains usually have fewer than five trophic levels
Only 10% of energy is transferred from one trophic level to the next. The loss of energy at each step is so great that very little usuable remains after four or five levels.
Explain why it is more energy efficient for
humans to eat crop plants than to eat livestock
that have been fed on crop plants
1) Crops is at a lower trophic level than animals
2) energy is lost between trophic levels
3) 10% of energy is lost
4) lost by respiration/metabolic
5) lost by movement/muscle contraction
6) material that is inedible/not digested
7) energy lost by excretion
8) less fuel required to farm seaweed
population
a group of organisms of one species, living in the same area, at the same time
community
all of the populations of different species in an ecosystem
ecosystem
a unit containing the community of organisms and their environment, interacting together
factors that affect the rate of population growth
food supply, competition, predation and disease
4 phases of sigmoid growth curve
lag phase, log phase, stationary phase and the death phase
lag phase
organisms are adapting to the environment before they are able to reproduce
- few organisms and so reproduction is not producing larger numbers of offspring
log phase (exponential phase)
food supply is abundant, birth rate is rapid and death rate is low; growth is exponential and only limited by the number of new individuals that can be produced
stationary phase
population levels out due to a factor in the environment, such as nutrient, becoming limited as it is not being replenished.
- birth rate and death rate are equal until either the nutrient is replenished or becomes severly limited
death phase
population decreases as death rate is now greater than birth rate; usually because food supply is short or metabolic wastes produced by the population have built up to toxic levels
Why are organisms in natural environments unlikely to show population growth like a sigmoid growth curve
Because they are affected by many other factors, including:
- changing temperature or light
- predators
- disease
- immigration (individuals moving into the area)
- emigration (individuals moving out of the area)
nitrification
Converts ammonia ions to nitrate ions.(Occurs in the soil with nitrifying bacteria)
denitrification
Converts nitrate ions to nitrogen gas
(Occurs in the soil with denitrifying bacteria)
nitrogen fixation
Converts nitrogen gas to ammonia ions.
(Occurs in the soil or in root nodules of legumious plants wtih nitrogen-fixing bacteria)
deamination
the removal of the nitrogen part of excess amino acids to produce ammonia. Which is then converted to urea.
negative impacts of chemicals to the natural environment, other than fertilisers
Pesticides/insecticides/herbicides;
kill/harm non target species;
loss of biodiversity/disrupt food chains;
bioaccumulation;
pollute area;
antibiotic resistance;
Treatment of sewage
- screening/removal of, large pieces of waste;
- flocculation/coagulation/clump suspended particles
- settling of insoluble particles
- digestion/decomposition by bacteria
- with aeration tank/activated sludge
- slugde should be treated with anaerobic decomposers
- water treated with chlorine/UV
- distillation/collection of water from evapourater
Explain why it is more energy efficient for humans to eat crop plants than to eat livestock that have been fed on crop plants.
Plants are at a lower trophic level than livestock;
Energy transfer along food chain is inefficient;
Energy is lost in metabolic processes;
More material that is lost of faeces;
Energy lost in excretion/urine;
