Ecology Flashcards
All about organisms, the environment they live in, and how the two interact.
Habitat
The place where an organism lives.
Population
All the organisms of one species living in a habitat.
Community
The populations of different species living in a habitat.
Abiotic factors
Non-living factors of the environment.
Biotic factors
Living factors of the environment.
Ecosystem
The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
Competition
Plants compete for light, space, water, and mineral ions.
Animals compete or food, mates, and territory.
Why do organisms need resources from the environment/ surroundings and from other organisms?
-To survive
-To reproduce
What is a stable community?
A community where all the species and environmental factors are in
balance so that population sizes remain fairly constant.
What things may different species depend on each other for within a community?
-food
-shelter
-pollination
-seed dispersal
What makes an ecosystem interdependent?
Different species depending on each other within a community.
In an interdependent ecosystem, what happens if a major change in the ecosystem occurs? (e.g. the removal of one species)
The affects can be far-reaching, affecting the whole community.
Why is it a problem that food webs are complex?
Knock-on effects of a change to one part of the ecosystem can be difficult to predict accurately.
What are the different levels of organisation in an ecosystem?
-Individual organisms (plants/animals)
-Populations
-Communities
-Ecosystems
Give an example of a stable community.
-Tropical rainforests
-Ancient oak woodlands
What would the loss of a primary consumer mean for other primary consumers?
Less competition for producers (name a specific one), so population will increase. (initially).
But also more likely to be eaten by predators so population will decrease.
What would the loss of a primary consumer mean for secondary consumers?
Less food so population will decrease.
What would the loss of a primary consumer mean for tertiary consumers?
Less food (if pops of secondary consumers decrease [name them]) so population will decrease.
How can feeding relationships within a community be represented?
-food chains
-food webs
What do food chains begin with?
A producer which synthesises molecules.
What are producers? (usually)
Green plant and algae which make glucose by photosynthesis.
What are the producers of biomass for life on Earth?
Photosynthetic organisms.
Predators
Consumers that kill and eat other animals.
Prey
Consumers which are eaten by predators.
In a stable community, what happens to the numbers of predators and prey?
The numbers rise and fall in cycles.
When asked to describe data, what must we do?
Be explicit and say what we see.
What are producers eaten by?
Primary consumers
What are primary consumers eaten by?
Secondary consumers
What are secondary consumers eaten by?
Tertiary consumers.
What can food chains be divided into?
Trophic levels.
What can trophic levels be represented by?
Numbers, starting at level 1 with
plants and algae.
Further trophic levels are numbered subsequently according to how far the organism is along the food chain.
Trophic level 1
Producers - Plants and algae that make their own food.
Trophic level 2
Primary consumers - Herbivores that eat plants/algae.
Trophic level 3
Secondary consumers - Carnivores that eat herbivores.
Trophic level 4
Tertiary consumers - Carnivores that eat other carnivores.
What are apex predators?
Carnivores with no predators (aka. organisms at the top of a food chain).
What are trophic levels?
The different stages of a food chain, consisting of one or more organisms that perform a specific role in it.
Why are there usually only four or five trophic levels in a food chain?
A lot of energy is lost from the food chain at each trophic level.
List the abiotic factors which can affect a community.
- light intensity
- temperature
- moisture levels
- soil pH and mineral content
- wind intensity and direction
- carbon dioxide levels (for plants)
- oxygen levels (for aquatic animals)
What can cause a change in the environment?
-An increase or decrease in an abiotic factor e.g. an increase in temperature
-The introduction of a new biotic factor e.g. a new predator or pathogen.
What can changes in the environment affect?
-The size of populations in a community.
-And hence the population sizes of organisms that depend on them.
-They have knock-on effects because of interdependence (biotic).
What is the effect of a decrease in light intensity, temperature, or carbon dioxide?
-Decreases the rate of photosynthesis in plant species
-This affects plant growth and could cause a decrease in the population size
-Animal species which depend on the plants for food may also be affected
What is the effect of a decrease in the mineral content of the soil? (e.g. a lack of nitrates)
-Causes nutrient deficiencies
-This affects plant growth and could cause a decrease in the population size
-Animal species which depend on the plants for food may also be affected
List the biotic factors which can affect a community.
- availability of food
- new predators arriving
- new pathogens
- competition - one species outcompeting another so the numbers are too low to breed.
Why is the population of red squirrels decreasing?
Red and Grey squirrels live in the same habitat and eat the same food.
Grey squirrels outcompete the red squirrels.
Adaptations
A feature an organism has that allows it to survive in its ecosystem.
What are the three types of adaptation?
-Structural
-Functional
-Behavioural
What is a structural adaptation?
Features of an organism’s body structure that allows it to survive in it’s ecosystem.
What is a behavioural adaptation?
Ways that an organism behaves that allows it to survive in it’s ecosystem.
What is a functional adaptation?
Things that go on inside an organism’s body related to processes like reproduction and metabolism that allows it to survive in it’s ecosystem.
Extremophiles
Organisms that are adapted to live in environments that are very extreme, such as at high temperature, pressure, or salt concentration.
Give an example of extremophiles
Bacteria living in deep sea vents (high pressure and salty)
What do we consider a large surface area to volume ratio?
If there is a big difference between surface area and volume.
What do we consider a small surface area to volume ratio?
If there is a small difference between surface area and volume.
What type of surface to volume ratio do animals living in hot climates have?
Large.
What type of surface to volume ratio do animals living in cold climates have?
Small.
Structural adaptations of animals in dry conditions
-Large ears
-Long legs
-A thin layer of fat (so not insulated)
-A large surface area to volume ratio
-All of the above to increase heat loss by radiation
Functional adaptations of animals in dry conditions
-Produce little sweat to conserve water
-Small amount of concentrated urine
What is essential to talk about - adaptations?
(Increased) surface area to volume ratio.
Heat loss
Give examples of behavioural adaptations.
-Nocturnal to reduce water loss/avoid predators/effective hunting
-Migration to warmer climates (South) in the winter
Structural adaptations of animals in cold climates.
-Thick layer of blubber for insulation reducing heat loss
-A low surface area to volume ratio to conserve heat
Functional adaptations of animals in cold climates.
-Hibernation in winter lowering metabolism which conserves energy and prevents e.g. brown bears hunting when there’s not much food available.
Adaptations of plants in dry climates
-Small leaves or spines to reduce surface area so less water is lost b y evaporation
-Long roots to absorb water from deep underground
-Waxy cuticle to reduce water loss by evaporation
Adaptations of plants in cold climates
-Become dormant in winter when there isn’t enough light for photosynthesis conserving water
-Low lying to protect from cold winds
Where does the energy for all biomass on earth come from?
The sun
When a green plant produces glucose, some of it is used to…
…make other biological molecules in the plant.
These biological molecules are the plant’s biomass.
What is biomass in simple terms?
-The mass of living material
-Can be thought of as the energy stored in an organism
How is energy transferred through living organisms in an ecosystem?
Organisms eating other organisms.
How do ecologists determine the distribution and abundance of species in an ecosystem?
By using a range of experimental methods using transects and quadrats
Why are predator-prey cycles always ‘out of phase’ with each other?
It takes a while for one population to respond to changes in the other population.
e.g. if the number of rabbits goes up the number of foxes doesn’t immediately, because because it takes time for them to reproduce.
What is a good ecology word?
Predation
Abundance
How many organisms there are.
Distribution
Where organisms are.
What is meant by sampling and why is it important?
Only counting a subset of the organisms in a habitat.
This is done because else it would be impossible or very difficult and time consuming, to count all the organisms.
What is a transect?
A line through a habitat along which organisms are sampled.
Interdependence
Within a community each species depends on other species for food, shelter, pollination, etc.
Ecosystem
The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of the environment.
Individual
Single organism
Adaptations
A feature an organism has that allows it to survive in its ecosystem.
Biodiversity
The variety of all the different species of organisms in an ecosystem.
Use of random quadrat sampling
Used to count total number of organisms in an area.
Random quadrat sampling method
randomly place quadrat (to avoid bias) and count organisms
-repeat 10 times and calculate a mean
-work out area of field and area of quadrat
-calculate total organisms by multiplying mean by number of quadrats that could fit in field
Use of transect line
Used to see pattern of organisms e.g. through a forest/across a river
Transect line method
-Place a transect line using a 30m tape measure
-Place the quadrat at 0m and count organisms. Record distance and organism number in table
-Move quadrat to 5m and repeat, moving 5m each time
-plot a graph to see pattern of results
Many different _________ cycle through the abiotic and ______ components of an _________.
materials
biotic
ecosystem
Explain the importance of the carbon cycle to living organisms.
Carbon returned to the atmosphere as carbon dioxide is used by plants in photosynthesis.
Biomass - glucose (needed for respiration) contains Carbon.
Explain the importance of the water cycle to living organisms.
The water cycle provides fresh water for plants and animals on land before draining into the seas.
Water is continuously evaporated and precipitated.
Why are materials in the living world recycled?
All materials in the living world are recycled to provide the building blocks for future organisms.
Explain the role of microorganisms in cycling materials through an ecosystem.
They return carbon to the atmosphere as carbon dioxide and mineral ions to the soil.
There are links with the water cycle to GCSE Chemistry…
…The Earth’s early atmosphere.
What’s it called when water penetrates the ground?
Percolation
Describe what happens in the carbon cycle.
Step 1
1- CO₂ is removed from the atmosphere by green plants and algae during photosynthesis. This carbon is turned into glucose, which can be turned into carbohydrates, fats, and proteins which make up the organisms.
Describe what happens in the carbon cycle.
Steps 2-3
2-When the plants and algae respire, some carbon is returned to the atmosphere as CO₂.
3- When the plants and algae are eaten by animals, some carbon becomes part of the fats and proteins in their bodies. The carbon then moves through the food chain.
Describe what happens in the carbon cycle.
Steps 4-6
4- When the animals respire, some carbon is returned to the atmosphere as CO₂.
5- When plants, algae, and animals die, other animals (called detritus feeders) and microorganisms feed on their remains. When these organisms respire, CO₂ is returned to the atmosphere.
6- Animals also produce waste (which is broken down by detritus feeders and microorganisms.
Describe what happens in the carbon cycle.
Steps 7-8
7- The combustion (burning of fuels including wood) also releases CO₂ back into the air.
8- So the carbon (and energy) is constantly being cycled - from the air, through food chains (via plants, algae and animals, detritus feeders and microorganisms), and eventually back into the air again.
Students should be able to evaluate the impact of environmental changes on the distribution of species in an ecosystem given
appropriate information.
Environmental changes affect the distribution of species in an ecosystem. (where they live)
These changes include what?
-temperature
-availability of water
-composition of atmospheric gases
The changes may be seasonal, geographic or caused by human interaction (e.g. global warming).
Give an example of how temperature effects the distribution of species in an ecosystem.
The distribution of bird species in Germany is changing as a result of rising temperature.
Give an example of how water availability affects the distribution of species in an ecosystem.
As rainfall patterns change, many species migrate to and from the tropics between the wet and dry seasons, e.g. wildebeest.
Give an example of how changes in the concentration of atmospheric gases affects the distribution of species in an ecosystem.
Where there is more air pollution, some species can no longer survive e.g. come species of lichen can’t grow in areas where sulfur dioxide is given out by certain industrial processes.
Why do microorganisms break down plant/animal material and waste?
To get energy
What are the factors that affect the rate of decay?
-Temperature
-Water
-Oxygen availability
-(Number of decay organisms)
Explain how temperature affects the rate of decay of biological material.
Warmer temperatures increase the rate that the enzymes involves in decomposition work at, so the rate of decay increases.
Explain how water affects the rate of decay of biological material.
The organisms involved in decay need water to survive and to carry out biological processes, therefore the rate of decay increases in moist environments.
process- secrete enzymes onto decaying matter, then absorb any dissolved molecules. Without water these reactions cannot occur.
Explain how oxygen availability affects the rate of decay of biological material.
Many of the organisms involved in decay do so aerobically (with oxygen).
They need oxygen to respire to release the energy needed for survival and to break down the biological material.
So, if more oxygen is available, the rate of decay is faster.
Decomposition
The process by which dead organic matter is broken down into simpler organic or inorganic substances, such as carbon dioxide, water, simple sugars, and minerals.
What groups of organisms carry out decomposition?
-Detritus feeders (small animals like worms and woodlice that feed on dead organic matter aka. detritivores)
-Decomposers (microorganisms, such as bacteria and fungi)
Gardeners and farmers try to provide optimum conditions for rapid decay of waste biological material. Why?
To make compost.
Compost
Decayed organic matter (e.g. food waste).
It is used as a natural fertiliser for growing garden plants or crops.
What can biogas generators be used for?
To produce methane gas which can be combusted as an energy source.
How is biogas made?
By the anaerobic decay of waste material:
-Different microorganisms decay plant and animal waste anaerobically (without oxygen)
-This type of decay produces methane gas (a type of biogas)
-Sludge waste from e.g. sewage works or sugar factories is used to make biogas on a large scale
-It is made in a simple generator called a digester/generator
Why do biogas generators need to be kept at a constant temperature?
So organisms can continue to respire and carry out the decay process.
What needs to happen to biogas - because it can’t be stored as a liquid?
It must be used straight away - for heating, cooking, lighting, or to power a turbine to generate electricity.
Why can’t biogas be stored as a liquid?
It needs too high a pressure.
What are the main 2 types of biogas generator?
-Batch generators
-Continuous generators
What do both batch and continuous generators need to have?
-An inlet for waste material to be put in
-An outlet for digested material to be put through
-An outlet so the biogas can be piped to where it’s needed
Batch vs continuous biomass generators
Batch - make biogas in small quantities, are manually loaded up with waste, products are cleared away at end of each session
Continuous - make biogas all the time so waste is continually fed in, biogas is produced at a steady rate (better for large scale biogas projects)
What is the purpose of using a random sampling method in a field investigation?
to avoid bias in sample selection
What IS a quadrat?
A square frame enclosing a known area e.g. 1m²
How de we estimate % cover
Count the number of little squares covered by organisms.
Explain HOW decomposers break down dead plant and animal matter.
-They secrete enzymes into the environment
-The enzymes break down dead material
-Small soluble food molecules then diffuse into the microorganism.
What do pyramids of biomass show?
The relative amount of biomass in each level of a food chain.
Trophic level 1 is at the bottom of the pyramid.
(You need to be able to construct these - use numbers to draw a scale and label each bar!)
Explain how biomass is lost between the different trophic levels.
-Not all of the ingested material is absorbed, some is egested as faeces
-Some absorbed material is lost as waste, such as carbon dioxide and water in respiration and water and urea in urine.
-Large amounts of glucose are used in respiration e.g. to provide energy for movement and keeping warm
How much of the incident energy from light do producers transfer for photosynthesis?
About 1%
How much of the biomass from each trophic level is transferred to the level above it?
Approximately 10%
How do we calculate the efficiency of biomass transfer between trophic levels?
[biomass transferred to the next level ÷ biomass available at the previous level ] x 100
How do we calculate biomass lost at each level?
Biomass at previous level - biomass at new level
Explain how energy loss affects the number of organisms at each trophic level.
Fewer biomass is available as trophic levels increase so the number of organisms decreases.
Except large producers like trees that have a big biomass (& lots of leaves for photosynthesis)
What is bioaccumulation?
The build up of toxic chemicals in a food chain.
The effect is much greater on organisms at the top of the food chain.
Why is compost used as a natural fertiliser??
It’s rich in the minerals that plants need to grow.
