23 - Ecosystems Flashcards
What is ecology?
The study of interactions between organisms and their environment
What is a producer?
An organism that makes its own energy and biomass using sunlight
What is a habitat?
An area which a population of organisms lives in
What is a niche?
The part of a habitat which an organism is best suited to
What is an environment?
All the conditions that surround a living organism
What is a consumer?
Organism which gets its biomass from producers or other consumers by eating them
What is a community?
All the living organisms in a habitat
What is a trophic level?
The level at which an organism feeds in a food chain
What is a detritivore?
An organism which consumes dead or decaying matter
What is a decomposer?
An organism which breaks down organic matter
What is an autotroph?
An organism which produces its own biomass
What is an abiotic factor?
A non-living factor which affects organisms
What is a biotic factor?
A living factor which affects organisms
What are heterotrophs?
Organisms which get their biomass by consuming organisms from other trophic levels
What is a population?
All the organisms of one species living in a habitat at one time
What is a microhabitat?
A small part of a habitat with specific conditions
What is an ecosystem?
All living and non-living organisms in a habitat and their interactions
Can abiotic and biotic factors affect each other?
Yes- each can affect the other
What are the 3 types of change which can affect population size?
- Cyclic changes 2. Directional changes (non-cyclic and go in 1 direction) 3. Unpredictable changes (no rhythm or constant direction)
What are 2 examples of cyclic changes?
Tides and day length
What is an example of a directional change?
Erosion
What is an example of an unpredictable change?
Natural disaster such as a tsunami
What is constantly recycled within an ecosystem?
Matter
What is not recycled within an ecosystem and why?
Energy, as it flows through the ecosystem
Are all ecosystems the same size?
No- they can be as small as a bacterial colony or be the whole Earth
What are 5 examples of abiotic factors?
- Light 2. Water availability 3. Soil type 4. Oxygen availability 5. Temperature
What are the 3 main types of soil?
- Clay 2. Loam 3. Sandy
How would you quantitatively represent a food chain?
Use a pyramid of number
What is a drawback of pyramids of number?
They only give an accurate impression of the flow of energy if the organisms are of a similar size
What is a drawback of using a pyramid of biomass?
As organisms have to be killed and dried to construct one, the sample size tends to be small
What type of biomass is used in a pyramid of biomass and why?
Dry mass as fresh mass is unreliable and varies
A pyramid of biomass is always what shape?
A pyramid
How do you calculate ecological efficiency?
(Biomass of primary consumer/Biomass of producer) x 100
What is productivity?
The rate at which energy passes through each trophic level
What is gross primary productivity?
The rate at which plants convert light energy to chemical energy
What (roughly) is this planet’s gross primary productivity?
Around 8%
What are 3 reasons gross primary productivity is less than 100%?
- Only 2/3 of glucose is used to respire 2. Only 40% of light energy enters the light reaction for photosynthesis 3. Only half of light energy is used for glucose production
How do you calculate net production?
Net production = Gross production - Respiratory losses
What is net production?
The amount of organic matter remaining after respiration
What are 7 ways of increasing net production?
- Increase light availability 2. Ensure ideal temperature 3. Use insecticides 4. Use fungicides 5. Ensure maximum nutrient availability 6. Use herbicides 7. Use irrigation/drought resistant strains
What is biomass?
The amount of living material present in a particular place or within organisms
What units is biomass measured in?
Grams per metre squared (on land) or per metre cubed (in water)
What is ecological efficiency?
The efficiency at which biomass or energy is transferred between one trophic level and the next
What is nearly always true about biomass and trophic levels?
Increasing trophic levels generally see a decrease in biomass
What are 4 reasons consumers do not convert all the biomass from their food into their own organic tissue?
- Not all biomass of an organism is eaten (i.e. bones) 2. Some energy transferred to environment as metabolic heat due to movement and respiration 3. Some energy lost via excretory materials 4. Some parts of an organism eaten but indigestible
What are 4 ways humans can manipulate biomass transfer in agriculture?
- Create very simple food chains 2. Keep abiotic factors ideal 3. Minimise interspecific competition 4. Remove threat of predators
What 2 things are the most common decomposers?
Microscopic fungi and bacteria
What is saprobiotic nutrition?
Obtaining nutrients from dead organic matter using extracellular digestion.
What do decomposers release back into the environment?
Stored inorganic compounds and elements
How does saprobiotic nutrition work?
The extracellular enzymes break down complex organic molecules into simpler, soluble ones which the decomposer then absorbs
What is the primary difference between detritivores and decomposers?
Decomposers digest using extracellular enzymes, detritivores perform internal digestion
What are 2 examples of detritivores?
Woodlice and earthworms