B4 - ecosystems (from PMT) 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
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 the 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 the 3 types of interdependence?
mutualism, parasitism and predation
give 4 things that 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 biomass
the dry mass of all of the living organisms in an area
