chapter 19: organisms and their environment Flashcards
explain the sun in terms of energy
it is the principal source of energy input to biological systems
describe the flow of energy through living organisms
- light energy from the sun
- chemical energy in the primary consumers transferred ro secondary consumers
- digestion of the primary consumers releases energy
- energy used for growth and protein synthesis, contribiting to the production of biomass in the secondary consumers
- energy eventually transferred to environment
describe a food chain
showing the transfer of energy from one organism to the next, beginning with a producer
describe a food web
a network of interconnected food chains
describe a producer
an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
describe a consumer
an organism that gets its energy by feeding on other organisms
describe a herbivore
an animal that gets its energy from eating plants
describe a carnivore
an animal that gets its energy from eating other animals
decomposer
an organisms that gets its energy from dead or waste organic material
describe interdependence in food webs
how the change in one population can affect others within the food webs
describe the impact humans have on the interdependence of food chains and food webs
- most of the changes are a result of human impact such as overharvesting of food species or by the introduction of foreign species to a habitat
- due to interdependence, these can have long lasting knock-on effects
describe a pyramid of numbers
- shows how many organisms are present at each level of a food chain
- width of the box indicates the number of organisms at that trophic level
describe a pyramid of biomass
- shows how much living matter is present at each trophic level of a food chain
- biomass is the dry mass of an organism with all the water gone
why is it better to use a pyramid of biomass then a pyramid of numbers?
- it takes into account the size of organisms at each trophic level and offers a more accurate representation of the living matter within an ecosystem
- biomass can be used as an approximate representation of the energy available at each trophic level
what is a trophic level?
the position of an organism in a food chain
describe the advantages of pyramids of energy over pyramids of biomass
- highlights the energy lost at each trophic level
- different organisms may not all store the same amount of energy in their biomass, so the pyramids of energy allow for more accurate comparisons
why is it more energy efficient to consume organisms from lower trophic levels?
- energy is lost at each trophic level
- indigestible parts, metabolism, heat transfer, excretion
in terms of energy loss, why do food chains usually have fewer than five trophic levels?
inefficient transfer of energy at each trophic level means that there is not enough energy available to sustain more than 5 trophic levels
describe the carbon cycle
- photosynthesis: carbon taken from the atmosphere in the form of carbon dioxide for photosynthesis
- respiration: carbon is returned to the atmosphere in the form of carbon dioxide by plants, animals, and microorganisms as a result of respiration
- feeding: carbon is passed on to animals and microorganisms by feeding
- decomposition: if animals and plants die without decomposing microorganisms the carbon can be converted into fossil fuels
- fossil fuels: combustion of fossil fuels causes carbon to combine with oxygen and carbon dioxide is released into the atmosphere
describe the nitrogen cycle
- nitrogen gas from the air is converted to nitrate compounds by the process of nitrogen fixation, which is converting inert nitrogen forms into reactive nitrogen forms
- lightning: makes nitrogen react with oxygen which forms nitrate when washed into the soil
- nitrification: converting ammonium ions to nitrates with the use of nitrifying bacteria
- denitrification: converting nitrate ions to nitrogen gas with the use of denitrifying bacteria
—— - decomposition of plant and animal proteins to ammonia ions
- absorption of nitrate ions by plants
- production of amino acids and proteins from nitrogen
- feeding and digestion of proteins
- deamination
where do nitrogen-fixing bacteria live
in the soil or root nodules on plants
how do nitrogen-fixing bacteria work
they use nitrogen gas from the air spaces in the soil and combine it with other substances to make ammonium ions and other compounds
describe a population
a group of organisms of one species, living in the same area, at the same time
describe a community
all of the populations of different species in an ecosystem
