B18 - Biodiversity and Ecosystems Flashcards
D. Biodiversity?
The measure of the variety of all species and organisms on Earth, or within a particular ecosystem
High biodiversity helps to ensure…
stability of an ecosystem by reducing the dependence of one species on another
Effects of fertiliser in the waterways?
- stimulates the growth of algae and water plants
- plants die because unable to photosynthesise
- means more microorganisms feed on dead pants
- less oxygen in water as microorganisms respire
- fish die
Why are peat bogs mainly destroyed?
- peat is burnt as fuel
- widely used by gardeners to improve soil quality
Peat is a large store of…
carbon
Ways of maintaining biodiversity? (4)
- breeding programs for endangered species
- protection and regeneration of rare habitats
- reintroduction of field margins and hedgerows
- reduction of deforestation
D. Trophic levels?
The position of organisms within a food chain
Trophic level 1
producers
Trophic level 2
primary consumers (herbivores)
Trophic level 3
secondary consumers ( carnivores who eat herbivores)
Trophic level 4
tertiary consumers ( carnivores who eat secondary consumers)
Apex predators?
predators with no predator
How do decomposers break down dead mass?
by secreting enzymes into the environment. small soluble food molecules then diffuse back into the microorganism down the conc gradient
How much of the biomass from each trophic level is transferred to the next one?
10%
Why do losses of biomass occur?
Because not all ingested material is absorbed, some excreted, some used in respiration, some lost as urine etc.
