19. Organisms And Their Environment Flashcards
what is the main source of energy in biological systems
the sun
describe the flow of energy in biological systems
- light energy from the sun is trapped by photosynthetic organisms
- energy is stored as chemical energy in organisms
- energy is eventually lost to the environment
what is a food chain
a way of showing the flow of energy between organisms starting with a producer
how is energy transferred between organisms in a food chain
by ingestion
what is a trophic level
the position that an organism holds in a food chain, food web, pyramid of numbers or pyramid of biomass
why are biomass transfers not 100% efficient
egestion
excretion
respiration
the production of inedible bones and shells
why do food chains usually have fewer than 5 trophic levels
biomass transfers are not 100% efficient and so there is often not enough energy to support 5 trophic levels
why is it most efficient to supply plants as food for humans
using the plants as food for livestock wastes energy as the biomass transfers are not 100% efficient
eating plant transfers can maximize the amount of energy gained as there is only on transfer
what is a food web
multiple interconnected food chains
what is a producer
an organism that makes its own food
what is a consumer
an organism that gets its energy by eating other organisms
what is a primary consumer
an organism that feeds on producers
what is a secondary consumer
an organism that feeds on primary consumers
what is a tertiary consumer
an organism that feeds on secondary consumers
what are herbivores
herbivores are animals that only eat plants
what are carnivores
organisms that mainly eat animals
what are decomposers
organisms that break down dead matter
explain the impact humans have on food chains and webs by over harvesting certain species
many organisms rely on other organisms for food, over harvesting can reduce the amount of food available for other animals
explain the impact humans have on food chains and webs by introducing other species into a habitat
introducing new organisms increases competition and can interfere with the food chain, causing organisms who cannot compete to die
what is a pyramid of numbers
a pyramid of numbers shows the number of organisms at each trophic level
what is a biomass pyramid
a pyramid that shows the total dry mass of organisms at each trophic level
why is a pyramid of biomass a better way of representing a food chain than a pyramid of numbers
pyramids of biomass take into account the size of the organisms and are less easily misinterpreted
describe the carbon cycle
- plants fix carbon dioxide into organic molecules during photosynthesis
- the organic carbon containing molecules are passed onto organisms that eat the plants
- carbon dioxide is released back into the atmosphere by respiration from animals and plants
- burning fossil fuels also releases carbon dioxide into the atmosphere
state the effect of burning fossil fuels on carbon dioxide concentration in the environment
burning fossil fuels releases more carbon dioxide into the atmosphere increasing the concentration of CO2
state the effect f deforestation on carbon dioxide concentration in the environemnet
- trees take in carbon dioxide during photosynthesis
- cutting down trees prevents this and so the atmospheric carbon dioxide concentration does not decrease
describe the water cycle
- water from lakes and oceans evaporate
- the evaporated water condense into clouds and returns to each as percipitation
- the water from precipitation is useful for life on land
- the water then returns to rivers and oceans through surface runoff
why is the water cycle imporatnt
living organisms require water
the water cycle provides organisms on land with a continuous supply of water
describe how nitrogen is cycled through an ecosystem
- nitrogen is fixed by lightning and bacteria
- decomposers break dead matter down into ammonium ions
- nitrifying bacteria convert ammonia into nitrates and nitrites
- denitrifying bacteria release nitrogen back to the atmosphere
what is deaminiation
the removal of the amine group in an amino acid
state 4 roles of bacteria in the nitrogen cycle
decomposition
nitrification
denitrification
nitrogen fixation
define population
a species that occupy the same habitat at the same time
define community
all the different populations in an ecosystem
define ecosystem
both the community and their physical environment
state 3 factors that affect population growth rates
disease
predation
availability of food
name the sections of this chart showing growth in an environment with limited resources
describe the ag phase in population growth
the organisms are adjusting to their environment
describe the log phase in population growth
the growth of the population is increasing at a fast rate
describe the stationary phase in population growth
the amount of births and deaths are equal
describe the death phase in population growth in an environment with limited resources
once the resources begin to be used up, organisms begin to compete for resources and organisms will die as resources become scarce
state 4 implications of a rapidly increasing population size
- more land needed for living
- greater demands on healthcare
- greater demands on education
- more resources needed which puts pressure on the environment
