Ecosystems Flashcards
Habitat?
Place where an organism lives
Population?
All the organisms of one species in one habitat
Producer?
An organism that produces organic molecules using sunlight energy e.g plants
Consumer ?
An organism that eats other organisms e.g animals/birds
Decomposer?
An organism that breaks down dead or undigested organic material e.g bacteria/fungi
Trophic level?
A stage in a food chain occupied by a particular group of organisms e.g producers are the 1st trophic level of the food chain
Ecosystem?
All the organisms living in a certain area / all non living factors living there
- dynamic system - changes over time
Abiotic/biotic factors on rock pools?
BIOTIC : seaweed is food source for consumers like limpets
- intense comp for food can limit no. Organism present in ecosystem
ABIOTIC : tides - can be completely submerged by ocean at high tides so experience similar abiotic factors : pH , Salinity , Temperature etc.
at low tide, more extreme abiotic factors ( higher salinity /temps) - only some organisms tolerate
Playing field biotic/abiotic factors?
BIOTIC : large amounts of plants (producers) attract large number of organisms as FOOD SOURCE
ABIOTIC: rainfall/sunlight affect growth of producers —> heavy rain can cause soil to be waterlogged so hard for growth
- reduces no. Consumers the ecosystem can support
Large tree biotic and abiotic factors?
BIOTIC: insects can use leaves of trees as FOOD SOURCE
- however overconsumption of leaves can slow tree growth /lead to death of tree
ABIOTIC : drought can lead to death of tree/negatively impact growth of tree
What are biotic and abiotic factors and examples?
Biotic : living features of the ecosystem - predation/competition for food, water,light or space / disease / camouflage and mimicry /no. And types of animals/plants
Abiotic : non-living features of ecosystem - temperature /rainfall /soil nutrient availability /humidity /salinity/pH /turbidity (cloudiness) of water/light intensity
What is biomass?
Mass of living material of the organism /tissue
Chemical energy that is stored within organism/tissue
What can biomass be measured in terms of?
Dry mass of organism /tissue
Mass of carbon that organism /tissue contains - generally taken as 50 % of dry mass
Chemical energy content of organism when burned in pure oxygen
What is calorimetry used for? Process?
Used to estimate the chemical energy stored in dry biomass
1. Involves burning sample of dry biomass in calorimeter
2. Burning sample heats known volume of water
3. Change in temp of water provides an estimate of chemical energy the sample contains
Why is a large proportion of sun’s energy not available for photosynthetic plants?
Light falls away from plants - misses chloroplasts
Light passes through leaves /reflected away
Light is a mixture of wavelengths - Only certain wavelengths stimulate photosynthesis
Why is only a small percentage of biomass transferred to next trophic level?
- not all of plant’s biomass is eaten by primary consumer
- not all consumer’s biomass intake is DIGESTED
- chemical energy is converted to mostly MOVEMENT AND HEAT - only *small amount to new biomass
Efficiency of biomass transfers between trophic levels EQUATION?
Efficiency of transfer = (biomass transferred / biomass intake ) x 100
Or
efficiency = net productivity of primary consumers/ net productivity of producers
Net productivity of producers /net primary productivity (NPP) EQUATION? What is it?
Amount of energy available to next trophic level (Kj m-2 yr-1)
NPP = GPP - R
GPP = gross primary productivity (energy taken in - rate at which plant convert light energy—> chemical energy by photosynthesis)
R = respiratory losses
Net productivity of consumers equation?
N = I - (F + R)
I = chemical energy store in ingested food
F = chemical energy lost to environment in faeces/urine
R = respiratory losses to environment
How does human activity manipulate the efficiency of biomass transfer?
Farmers can increase agricultural productivity by increasing biomass transfers by:
For producers :
- Irrigation to maximise growth in dry weather
- Use of fertilisers - growth of plants
- Selective breeding for fast growth
- Use of fungicides/pesticides
For primary consumers :
- Use of good quality feeds / food supplements
- Use antibiotics and vaccines to reduce disease
- Control predation with fencing etc
- Intensive control of conditions to reduce energy loss from movement or from getting cold outside
What are decomposers known as and how do they break down organic/waste matter?
Saprobionts - from fungi/bacteria kingdom
- They secrete enzymes onto dead organisms/waste material which digest the material externally - EXTRACELLULAR DIGESTION
Products of extracellular digestion is then absorbed by SAPROBIONTS
This method is known as SAPROBIOTIC NUTRITION - not all products of extracellular digestion are absorbed by Saprobionts/many remain in surrounding for other organisms
Why are Saprobionts essential ?
Nutrients would be locked up in dead/waste matter and wouldn’t be made available again for producers to use
- also some Saprobionts can excrete important nutrient mineral ions as waste products from their own metabolism
What is mycorrhizae ?
The symbiotic (mutually beneficial) relationship between fungi and plants
Fungi’s hyphae interact with plant roots / increase SA of root system of plants —> INCREASE WATER AND MINERAL IONS ABSORBTION
- in return fungi receive organic compounds (e/g glucose) from plant
Role/reactants and location of nitrogen fixing bacteria? (Azotobacter and Rhizobium species)
Convert gaseous nitrogen into AMMONIA (NH4+) -ANAEROBIC process
Reactants: N2 + H+—> NH3 (reduction)
Location: root nodules , leguminous roots
NH3 can be converted into amino acids
Rhizobium form mutualistic relationship with plants- provide plant with nitrogenous compounds /plant provides carbs to them
Abiotic process: lightning, artificial fertilisers, haber process also fix N2