B4 Ecosystems Flashcards
Producers
Organisms that make their own food by photosynthesis (plants/algae)
Consumers
Organisms that can’t make their own food, have to eat other organisms to gain energy (all animals)
Decomposers
Special group of consumers, gain energy by feeding on dead/decaying material
How is energy transferred to producers
- energy from sun transferred by light to chlorophyll in cells of producer
- photosynthesis takes place here (co2 & h2o react to make glucose)
- glucose stores energy within its chemical bonds
- glucose can be converted into carbs, fats, proteins: used as energy stores, growth, repair
Biomass
= mass of living material present (increases as organism grows)
How is energy transferred between organisms
- consumers eat producers
- when organism respires, energy stored in its food transferred in production of ATP
- organism grows & biomass increases
- process continues
Trophic level
Each step in a food chain
What do the arrows in a food chain show
The transfer of biomass (energy transfer) from one organism to the next
Trophic levels of a food chain
- producer
- primary consumer (herbivore)
- secondary consumer (carnivore)
- tertiary consumer
What makes food webs better than food chains
Food webs contain a series of interlinked food chains as most animals eat more than one type of organism
Biotic factors
Living factors
Biotic(living) factors of an ecosystem
Competition for:
- food
- space
- breeding partners
Abiotic (non-living) factors
- light intensity
- temperature
- moisture level (rainfall)
- soil PH
How does light intensity affect communities?
Light required for photosynthesis,
greater light availability = greater success/growth of plant
Plants evolve to grow successfully in different light intensities (larger leaves in low)
How does temperature affect communities
- temp affects enzymes which control metabolic reactions
- warmer temp = faster metabolism = more rapid development (for plants, cold blooded animals)
How does moisture level affect communities
- lack of water = death (osmosis, wilt)
- needed for photosynthesis
How does soil pH affect communities
- soil pH affects biological activity & availability of certain minerals in soil
- some plants (rhododendrons, ferns) grow better in acidic soil (pH 1-6)
- some plants (cucumbers, cauliflower) grow better in alkaline soil (pH 8-14)
What do plants need to survive
- light
- water
- carbon dioxide
- minerals
- space
What do animals need to survive
- food
- water
- breeding partners
- space (territory)
- shelter
Interdependence, 3 main types
= how different organisms depend on each other within a community
- predation
- mutualism
- parasitism
Predation
= Relationship between a predator & prey species
- Size of predator population directly affects size of prey population
Mutualism
= both organisms benefit from relationship
(Eg. Oxpeckers are birds that eat ticks/fleas living on buffalos skin, gain food while buffalo free from irritation/disease)
Parasitism
= only 1 organisms (parasite) gains, organism it lives off (host) suffers
(Eg. Tapeworms in animals digestive system, fleas)
What do pyramids of biomass show
= population at each trophic level, bar width represents no. of organisms present
What is the general trend as you move from 1 trophic level to the next
- size of organisms (biomass) generally increases
- number of organisms generally decreases (except eg. oak tree)
How to calculate biomass
Average dry mass of each organism x no. of organisms present = total biomass at trophic level
(Organism killed & dried in a kiln)
When is biomass lost
- not all of an organism is eaten
- some biomass used in respiration
- some parts of organism can’t be digested (hair), removed from body in faeces (egestion)
- waste products produced by body lost through excretion (urine)
How much chemical energy in a consumers food is converted to new body tissue
10%
Why do very few food chains have more than 4 trophic levels
Not enough energy can be transferred to sustain life processes as less energy is transferred on each level
Decomposers
Microorganisms (bacteria/fungi) that break down/decay
- dead organic material at a microscopic level
- animal waste (faeces/urine)
To release nutrients which can be recycled
Saprophytes
Organisms that feed on dead material (decompose)
Detritivores
Small animals that speed up decomposition by shredding organic material into very small pieces to create a larger surface area for decomposers to work on
Examples of detritivores & material they break down
- earthworm: leaves
- woodlouse: wood
- maggot: animal material
How do decomposers release nutrients
- bacteria/fungi release enzymes, break down substances into organic matter
- absorb soluble nutrients into their bodies, use theme for growth/energy store
- bacteria/fungi may be eaten by other organisms, nutrients passed on
- some nutrients released directly into soil/environment
What conditions do microorganisms decompose materials most efficiently in
- warm temperatures
- moist environments
- aerobic conditions
Why do temps affect rate of decomposition
- high temps = enzymes in microorganisms denatured, prevents decomposition/death of microorganisms
- low temps = rate of enzyme-controlled reactions slow = rate of decomposition slow/rate of microorganism replication slow
Why do moist environments affect rate of decomposition
- not enough water available = reactions within microorganisms slow down/prevented = reduces/stops process of decomposition
Why do aerobic conditions affect rate of decomposition
- oxygen needed for microorganisms to respire
- anaerobic conditions prevent most forms of decomposition as microorganisms can’t survive
Rate of decay equation
Rate do decay (g/day) = change in mass (g) / time (day)
