B4.1 Flashcards
give 3 molecules which are cycled through ecosystems
oxygen, carbon dioxide and water
briefly describe how water is cycled through an ecosystem
water evaporates from rivers and lakes and from transpiration
water condenses as clouds
water is returned through precipitation
briefly describe how carbon dioxide is cycled through an ecosystem
carbon dioxide is fixed through photosynthesis
respiration releases carbon dioxide
decomposition releases carbon dioxide
combustion releases carbon dioxide
briefly describe how nitrogen is cycled through an ecosystem
nitrogen is fixed by lightning, the Haber process and bacteria
Denitrifying bacteria release nitrogen back to the atmosphere
why is recycling in ecosystems necessary?
to create a continuous flow of nutrients
to provide fresh water
how would a decrease in oxygen availability affect the rate of decomposition?
lack of oxygen causes microorganisms to respire anaerobically
anaerobic decay is slower than aerobic decay
how would a decrease in water availability affect thee rate of decomposition?
decomposing microorganisms need water for chemical processes.
the less water available, the slower the rate of these processes
how would a change in temperature affect the rate of decomposition
a decrease in temperature slows the rate of the decomposition reactions
a large increase in temperature will denature enzymes, slowing or even stopping decomposition
give 4 abiotic factors that affect communities
light intensity
temperature
soil pH
moisture levels
give 4 biotic factors that affect communities
number of predators
food availability
disease
human activity
what are 3 types of interdependence
mutualism, parasitism, and predation
what is parasitism
where one organism lives on another and takes nutrients from the other organism
this is beneficial to the parasite and detrimental to the host
what is mutualism
two organisms depend on each other
both of the organisms benefit from the relationship
give 4 things animals compete for
mates
space
food
water
give 4 things that plants compete for
light
water
minerals
space
what is a producer?
an organism that makes its own food
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 biomass
the dry mass of all of the living organisms in an area
why is dry mass used for biomass
because the wet mass varies as the amount of water in the organism varies
how do you calculate the efficiency of biomass transfer?
efficiency = (energy transferred / total energy available) x 100
why are biomass transfers not 100% efficient?
energy is lost through
egestion ( removal of faeces)
excretion (removal of urine)
respiration
the production of inedible bones and shells
how does the efficiency of biomass transfers affect the number of trophic levels in a biomass pyramid?
the less efficient the transfers, the fewer trophic levels and the fewer organisms in higher trophic levels
