23 - Ecosystems
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What is an ecosystem?
-All the interacting living organisms and the non-living conditions in an area -Dynamic -Range in size
What is a biotic factor?
Living components of an ecosystem
What is an abiotic factor?
Non-living components in an ecosystem
What are the biotic factors that affect ecosystems?
Interactions between organisms -Competition (intraspecific/interspecific) for food, territory, breeding partners, etc
What are the abiotic factors that affect ecosystems?
-Light: Affects photosynthesis, greater success of a plant species where light availability is greater -Temperature: Affects enzyme controlled metabolic reactions, both plants and ectotherms develop faster in warmer temps -Water availability: lack of water leads to water stress, causing wilting as water is required to maintain turgidity of cells, also needed for photosynthesis -Oxygen availability: necessary for respiration (fast flowing cold water, but not water logged soils) -Edaphic (soil) factors: CLAY - fine particles, easily waterlogged, clumps when wet / LOAM - particle size varies, retains water, not waterlogged / SANDY - coarse and separated particles, water drains, does not retain water, erodes easily
What is a trophic level?
Stage in a food chain
What is a food chain?
Diagram showing direction of energy flow
What is a food web?
Series of interlinked food chains
What is a producer?
Organism that coverts light energy into chemical energy
What is a consumer?
Organism that obtains its energy by feeding off another organism
What is biomass?
Mass of living material
List the trophic levels/
Producer - organism that converts light energy to chemical energy Primary consumer - animal that eats a producer Secondary consumer - animal that eats a primary consumer Tertiary consumer - animal that eats a secondary consumer Quaternary consumer- animal that eats a tertiary consumer
Why don’t food chains usually have more than five trophic levels?
There is not usually sufficient biomass and energy stored left to support any further organisms
What are the 3 types of ‘pyramids’ that represent food chains
Pyramid of energy Pyramid of biomass Pyramid of numbers
How do you calculate biomass at each trophic level
Multiply biomass of each organism by the total number of organisms in that area BUT water content must be discounted (dry mass) and must be killed to be dried
What is biomass measured in?
g/m^2 OR g/m^3
Why does biomass always decrease between successive trophic levels?
Only a small proportion of food ingested is converted into new tissue
What are the units for energy at each trophic level
kJ/m^2/yr
What is ecological efficiency?
Efficiency with which energy or biomass is transferred from one trophic level to the next
What is the efficiency of a producer
Convert 1-3% of light energy into chemical energy and hence biomass
Explain the efficiency of a producer
-Not all light energy available is used for photosynthesis (90% is reflected) -Other factors may limit photosynthesis -Some energy is lost as it is used for photosynthetic reactions
What is gross production?
The total light energy that plants convert into organic matter
What is the net production formula
Net production = gross production - respiratory losses
What is the efficiency at consumer level?
Convert at most 10% of the biomass into their own organic tissue