ecology Flashcards
define ecology:
the study of the relationships between living organisms and their physical environment
what is a habitat?
the environment in which an organism lives.
what is a population?
the total number of organisms of the same species living in the same geographical area.
what is a community?
the populations of all of the different species that live in the same habitat.
what do the words biotic and abiotic mean, and give examples of each:
living (animals, plants) and non-living (soil, climate, water, minerals).
what is an ecosystem?
the interaction of a community of living organisms with the non-living parts of their environment
what resources do plants compete with each other for, in order to stay alive?
plants compete with each other for light, space, water and mineral ions in the soil.
what resources do animals compete with each other for, in order to stay alive?
animals compete with each other for food, water, mating partners and territory.
why is competition important?
in the long run, it can increase species diversity, by acting as a force for specialisation and divergence.
what is interdependence?
the idea that all different species in a community depend on each other. e.g. for food, shelter.
- therefore if something happens to one of the species, it could affect the entire community.
what is a stable community?
a community in which the populations of organisms are in balance with each other, and with the abiotic resources (e.g. water), and so the populations remain relatively constant.
- in these communities, the numbers of predators and prey fall and rise in cycles.
what are the four different biotic factors, and explain them:
- food availability: all sources of food, which are relied on by animals, whether animals or plants, are a biotic factor. if the availability of food falls, the number of organisms in the community will also fall.
- predators: could cause the population of a prey species to fall. can also affect existing predators (e.g. when competing for the same prey).
- interspecies competition: if a species is outcompeted then its population can fall so much that numbers are no longer sufficient to breed and the species becomes extinct.
- new pathogens: if an infectious disease emerges and then spreads, it can wipe out a population of a species.
describe light intensity as an abiotic factor:
- can majorly affect plants.
- all plants need light to carry out photosynthesis.
- if the light intensity is too low, the rate of photosynthesis falls and plants will grow more slowly.
- therefore, animals which feed on these plants may not have enough food.
describe temperature as an abiotic factor:
- if the temperature of an environment changes, then this could cause the distribution of species to change.
- e.g. animals might migrate, and plant species would simply disappear.
- could also increase the rate of photosynthesis, as the enzymes work faster
- animals must also spend less energy staying warm, so can use more energy for growth
describe water as an abiotic factor:
- both plants and animals require water to survive.
- without water, their populations would decrease massively.
describe pH and mineral content of soil as an abiotic factor:
- important abiotic factor for plants.
- many plants can’t grow on soil which is too acidic or alkaline.
- plants also need certain minerals in the soil, such as nitrate ions, which are used to make amino acids for proteins.
describe wind intensity and direction as an abiotic factor:
- an important factor for plants.
- strong winds blowing inland can cause plants to lose water, which is essential to their growth and development.
describe carbon dioxide and oxygen supply as an abiotic factor:
- carbon dioxide is needed for plants to photosynthesise, and if carbon dioxide levels fall, then the rate of photosynthesis also decreases.
- oxygen is needed for aerobic respiration. oxygen levels in the air are fairly constant, but oxygen levels in the water can fall, especially on hot days. this can be harmful to aquatic organisms.
to recap, what are the seven abiotic factors?
light intensity, temperature, water, soil pH, soil mineral content, wind intensity and direction, and carbon dioxide and oxygen supply.
what is the difference between quantitative and qualitative data?
- quantitative data gives a specific measure (e.g. there are 502 daisies).
- qualitative data gives a rough idea (e.g. there are lots of daisies).
what factors can affect the abundance of a plant in a field?
- light intensity
- the presence of other organisms (e.g. humans)
- natural chemicals
- soil fertility
define competition:
animals and plants have to compete for limited resources. the best adapted species will win and survive.
what is the difference between interspecific and intraspecific competition?
interspecific: competition between animals of different species.
intraspecific: competition between animals of the same species.
why might some plants and animals want to compete?
- plants compete for light, to photosynthesise and make food. they also compete for mineral ions in the soil, in order to grow. they also compete for space and water.
- many animals cannot reproduce if they don’t have territory. therefore they must compete for it. some animals use urine or faeces to mark the boundaries of their territory.
why might some animals avoid competition?
- some animals may avoid competition because they’re too young.
- animals may not need to compete because there are plenty enough resources.
- some animals may be able to avoid competition and still obtain resources as it’s dependent on their adaptations (e.g. giraffes can obtain resources from high up, while other species can’t).
how can some plants avoid competition?
- by not taking up as much space.
- by dispersing their seeds so they can reproduce elsewhere (in the wind, by animals, on water).
- some plants’ roots can grow longer and bigger to obtain water and minerals.
- they can grow taller to receive more sunlight.
what is an adaptation?
characteristics which enable an organism to survive in their particular habitat.
define behaviour:
the way in which an organism acts. this can be instinctual or learnt.
what is the difference between functional and structural adaptations:
functional: how an organism’s body works
structural: an organism’s physical features
what is an extremophile?
an organism (bacteria, archaea) that lives in conditions we find extreme. (e.g. thermophiles live in extremely hot conditions).
- high temperature
- high pressure
- high salt concentration
- bacteria living in deep sea vents are also called extremophiles.
what are the structural adaptations of a camel when living in hot, dry conditions?
- wide feet; prevents them from sinking into the sand.
- long eyelashes; keeps the sand from blinding them.
- brown, thin, silky fur; brown fur allows them to camouflage from predators. thin fur increases heat loss.
- large ears; provides a large surface area for radiating heat.
what are the functional adaptations of a camel, and other animals, when living in hot, dry conditions?
- camels store water as fat in their hump.
- some animals produce uric acid rather than urea as it uses less water.
- some may also be venomous to allow them to catch their prey, or be toxic to deter predators.
what are the behavioural adaptations of a camel, and other organisms, when living in hot, dry conditions?
- organisms tend to be more active at night; allows them to avoid the heat of the day.
- animals that are awake in the day tend to stay in the shade or near a water supply.
what are the structural adaptations of an animal living in cold conditions?
- smaller surface area : volume ratio, helping them to stay warm and minimising heat loss (this is why seals, walruses, polar bears, and whales are quite large).
- small ears; reduces cooling through heat transfer.
- insulation (thick coat/blubber); keeps the animal warm.
- light coats; provides camouflage, allows them to sneak up on prey or avoid predators.
what are the functional adaptations of an animal living in cold conditions?
- to ensure camouflage all year round, some animals have a summer coat that is brown or grey that blends in with both snow and bare ground.
- many fish produce proteins that prevent their blood from freezing.
what are the behavioural adaptations of an animal living in cold conditions?
- breed in winter; this means offspring will be ready to leave in the summer, when lots of food is available.
- many animals migrate to different areas between summer and winter, ensuring good food supply all year round.
describe producers in a food chain:
- always begins with a producer (e.g. green plants, alga). usually a green plant which can feed itself by photosynthesis. synthesises complex molecules (e.g. glucose), called biomass, which its consumers can utilise.
- PHOTOSYNTHETIC ORGANISM.
what is a food chain?
shows what gets eaten by what in an ecosystem
- simplified version of a food web, as it only shows one chain, not all of them
what is the order of a food chain?
producer - primary consumer - secondary consumer (some type of predator) - tertiary consumer - quaternary consumer - apex predator
describe the difference between predators and prey:
- predators are consumers that kill and eat other animals.
- animals eaten by predators are called prey.
- the animal at the top of the food chain, with no predators, are called apex predators.
what are predator-prey cycles?
- the populations of both species cycle up and down
- the change in the predator population always lags behind the change in prey population slightly: they’re out of phase with each other
what is sampling?
- we can’t determine the abundance and distribution of all organisms exactly, as this would be time-consuming/impossible
- instead, ecologists use ‘sampling’, where they only measure a subset of organisms and use that subset to make predictions about the whole population
describe how and why we do random sampling:
- uses a quadrat (to measure abundance). place it on the ground, count the number of organisms inside the quadrat.
- can be used to sample plants or slow-moving animals.
- quadrat is placed at random locations across the area.
what is a quadrat?
a square frame that has been subdivided into lots of smaller squares. we can use these to sample a habitat and estimate the size of a population
how do you calculate the total population size of a species in an area?
total population size = total area/area sampled x number of organisms of that species counted in that sample
describe transects:
used to see if the number of species change as we move across a habitat
- usually a strip/line of tape
how do we measure the distribution of a species using a transect?
- a transect line is laid out between two areas
- quadrats are placed at regular intervals along the line
- the abundance of dandelions is measured by counting the number of dandelions in each quadrat along the transect line
- steps 1-3 are repeated with new transect lines (these must be parallel to the first). the data gathered is therefore more representative of the area
describe the carbon cycle:
- the carbon cycle starts with carbon dioxide in the atmosphere.
- plants and algae take in carbon dioxide from the atmosphere through photosynthesis.
- the carbon is used to make carbohydrates, fats and proteins (biological molecules) which makes up the cells of plants and algae.
- some of the carbon dioxide returns back to the atmosphere through aerobic respiration.
- plants and algae are also eaten by animals, which are then eaten by other animals, and the carbon passes from organism to organism.
- animals also respire, and some of the carbon is once again released back to the atmosphere as carbon dioxide.
- animals release waste products, and all plants and animals eventually die, this returns carbon to the soil. this is decomposed by decomposers, which carry out aerobic respiration, returning the carbon to the atmosphere.
- if these dead remains are decayed in anaerobic conditions, they may be slowly converted into fossil fuels. these are then burned by humans to add carbon back into the atmosphere
what is the importance of the carbon cycle?
returns carbon from organisms to the atmosphere as carbon dioxide to be used in photosynthesis by plants.
why is recycling important in an ecosystem?
- the conservation of matter principle states that matter cannot be created or destroyed - if recycling didn’t occur, the ecosystem would eventually reach an equilibrium where there isn’t enough matter to support new life.
- therefore carbon, nitrogen, and phosphorus are being constantly recycled through photosynthesis, respiration, decomposition and consumption. this cycling ensure a continuous supply of these essential elements for the organisms in the systems.
- recycling provides the building blocks for future organisms.
why are decomposers (e.g. bacteria, fungi) important?
decomposers are important as they cycle materials through an eco-system. they re-introduce vital elements such as nitrates (used by plants to synthesise proteins and amino acids, allowing them to gain energy), and potassium back into the soil and atmosphere, allowing plants to take in these elements and use them for growth. they also release carbon back into the atmosphere as carbon dioxide.
- this is done by digesting materials using enzymes and returning nutrients and minerals back into the soil, or shredding dead plant matter, which releases the trapped nutrients in the plant tissues.
- dead organic matter is broken down into simpler organic/inorganic substances (e.g. CO2, water, simple sugars, minerals)
what happens when a decomposer cannot function effectively?
- a decomposer may not be able to function effectively if there is a shortage of oxygen.
- if this happens, the carbon in the dead remains is slowly converted to fossil fuels, and trapped underground.
- however, over the last 200 years, humans have been burning huge amounts of fossil fuels, releasing large amounts of carbon dioxide back into the atmosphere.
describe the water cycle:
- almost all water on Earth is found in oceans, as salt water.
- the sun’s energy causes the water to evaporate from the surface of the sea, rivers, lakes, and the soil
- can also evaporate off the surface of leaves, called transpiration
- the water vapour travels further into the air and cools down, condensing to form clouds.
- the water in clouds then falls back to the ground as precipitation (this is fresh water).
- once the water hits the ground, some of it simply evaporates back into the atmosphere as water vapour. some water passes through rocks and forms aquifers. most of the water forms or joins rivers or streams, eventually draining back into the sea.
what role do living organisms play in the water cycle?
- plants take up water in their roots.
- this water passes up the stem in the xylem, and passes out of the leaves, through the stomata, as water vapour (transpiration).
- animals take in water through their food and drink, and release it in their faeces and when they exhale.
describe the importance of the water cycle:
provides fresh water for plants and animals on land, before draining into the seas.
describe compost heaps:
farmers put dead plant material onto the compost heap (plenty of oxygen, warm, moist are the ideal conditions). over time, bacteria and fungi decompose this plant material and produce compost. gardeners and farmers then use this compost as a natural fertiliser - this is because compost is very rich in the minerals plants need to grow.
- higher temps means that the overall process is sped up, as the enzymes involved in the decomposition process are supplied with more energy and are more productive.
describe the factors that affect the rate of decomposition:
temperature: decomposition takes place faster at warmer temperatures. this is because decomposers use enzymes to break down plant material, and these enzymes work faster in warm conditions
- too high temperatures denature the enzymes, and decrease the rate of decomposition
water: decomposers work faster if the compost is moist. many of the chemical reactions in decay require water. unable to reproduce or feed if water is unavailable
- however, if the soil becomes waterlogged, oxygen levels fall, increasing the rate of decomposition
oxygen: decomposers carry out aerobic respiration, requiring a good supply of oxygen. therefore more oxygen means more respiration, so more energy, and faster growth and decomposition
what do the arrows on a food chain represent?
the transfer of energy from one organism to another
- as the energy is passed up the levels, most of it is lost
what is the difference between detritivores and decomposers?
detritivores:
- worms, beetles, etc.
- break up dead material, increasing its surface area.
decomposers:
- bacteria and fungi
- complete the breakdown and decomposition process.
what is a saprotroph?
a microorganism which can cause decay e.g. decomposer, detritivore
- they produce enzymes which break the detritus into its constituent nutrients. they then absorb the released nutrients as food.
describe the production of biogas through anaerobic respiration:
- some saprotrophic enzymes cause decay in the absence of oxygen.
- if this were to occur in an airtight container (biogas generator) this could result in the production of methane and carbon dioxide (biogas), which has many domestic and industrial uses. methane can be used as fuel to power domestic electrical appliances, and the additional slurry produced can be used as a fertiliser in farmers’ fields.
- methane is however a powerful greenhouse gas, and if there is a leak, this can greatly worsen the greenhouse effect.
what human and physical processes remove and add CO2 to the atmosphere?
remove:
human - carbon capture, afforestation
physical - plants, absorption by oceans and geological processes.
add:
organisms - respiration/decay. burning of fossil fuels.
physical - forest fires, volcanic eruption.
what would happen if we didn’t have decomposers?
dead leaves, insects, and animals would begin to pile up as the recycling of material wouldn’t occur. many primary producers heavily rely on the nutrients decomposers release, leading to a population drop across the entire ecosystem.
