B7 - Ecology Flashcards
(102 cards)
1
Q
Habitat - definition
A
> The place where an organism lives
2
Q
Population - definition
A
> All the organisms of one species living in a habitat.
3
Q
Community - definition
A
> The populations of different species living in a habitat
4
Q
Abiotic factors- definition
A
> Non-living factors of the environment, e.g. temp.
5
Q
Biotic factors - defintion
A
> Living factors of the environment, e.g. food.
6
Q
Ecosystem - definition
A
> An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
7
Q
Survival of organisms
A
> To survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there.
8
Q
What do plants compete for?
A
> Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil.
9
Q
What do animals compete for?
A
> Animals often compete with each other for food, mates and territory.
10
Q
Interdependence
A
> Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community. This is called interdependence.
A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
11
Q
Example of stable communities
A
> Tropical rainforests
>Ancient oak woodlands.
12
Q
Abiotic factors that can affect a community
A
Abiotic (non-living) factors which can affect a community are: • light intensity • temperature • moisture levels • soil pH and mineral content • wind intensity and direction • carbon dioxide levels for plants • oxygen levels for aquatic animals.
13
Q
Abiotic factors that can affect a community - light, co2 or temp
A
> Could all affect rate of photosynthesis.
>So could affect plant growth and cause a decrease in the population size.
14
Q
Abiotic factors that can affect a community - mineral content
A
> Could cause nutrient defeciencies.
>Affect plant growth and cause a decrease in pop size.
15
Q
Abiotic factors that can affect a community - plants for food
A
> Animals depend on plants for food, so a decrease in a plants population could affect the animal species in a community.
16
Q
Biotic factors that can affect a community
A
Biotic (living) factors which can affect a community are:
• availability of food
• new predators arriving
• new pathogens
• competition - one species outcompeting another so the numbers are no longer sufficient to breed.
17
Q
Biotic factors that can affect a community - new predators
A
> A new predator could cause a decrease in the prey population.
18
Q
Biotic factors that can affect a community - competition
A
> Red and grey squirrels live in the same habitat and eat the same food.
Grey squirrels outcompete the red quirrels - so the population of red squirrels is decreasing.
19
Q
Adaptations
A
> Organisms have features (adaptations) that enable them to survive in the conditions in which they normally live. These adaptations may be structural, behavioural or functional.
20
Q
Adaptation - definition
A
> Features or characteristics that allow organisms to live in different environmental conditions.
21
Q
Adaptations - stuctural
A
> These are features of an organism’s body structure - such as shape or colour, for example:
- Arctic animals, arctic fox - white fur - camouflage - avoid predators - sneak up on prey.
- Animals in cold places, whale - thick layer of blubber + low surface area to volume ratio - helps retain heat.
- Animals in hot places, camel - thin layer of fat + large surface are to volume ratio - helps to lose heat.
22
Q
Adaptations - behavioural
A
> There are ways that organisms behave.
Many species (e.g swallows) migrate to warmer climates during the winter to avoid the problems of living in cold conditions.
23
Q
Adaptations - functional
A
> These are things that go on inside an organism’s body that can be related to processes like reproduction and metabolism. For example:
- Desert animals conserve water by producing very little sweat and small amounts of concentrated urine.
- Brown bears hibernate over winter - they lower their metabolism - conserves energy - so don’t have to hunt when less food about.
24
Q
Microorganisms adaptations
A
> Some organisms live in environments that are very extreme, such as at high temperature, pressure, or salt concentration. These microorganisms are called extremophiles.
Bacteria living in deep sea vents are extremophiles.
25
Food chains
>Feeding relationships within a community can be represented by food chains.
>All food chains begin with a producer which synthesises molecules.
>This is usually a green plant or algae which makes glucose by photosynthesis.
>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.
26
Biomass
>The mass of living material.
>Biomass can be thought of as energy stored in a plant.
>Energy is transferred through liing organisms in an ecosystem when organisms eat other organisms.
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Consumer - definition
>Consumers are organisms that eat other organisms.
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Primary condumer - defnition
>The first consumers in a food chain.
| >Secondary =2nd, tertiary= 3rd.
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Levels of a food chain
>Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers.
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Predator-prey population
>Pop of any species is usually limited by amount of food available.
>Pop of prey increases, so will op of predators.
>As pop of predators increases, no. of prey decreases.
>pREDATOr-prey cycles are always out of phase with each other as it takes a while for pop to repond to changes in other population - (as it takes take for them to reproduce for example.)
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Investigating species in area.
>A range of experimental methods using transects and quadrats are used by ecologists to determine the distribution and abundance of species in an ecosystem.
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Predators
>Consumers that kill and eat other animals are predators, and those eaten are prey.
>In a stable community the numbers of predators and
prey rise and fall in cycles.
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Quadrats
>A quadrat is a square frame enclosing an area , e.g. 1m^2.
>Used to compare how common an organism is in two sample areas (e.g. shady and sunny spots).
1. Place a 1m^2 quadrat on ground at a random point within first sample area. Get random point by dividing area into grid and use random number generator to select co-ordinates.
2. Count all organisms within quadrat.
4. Repeat as many times as you can.
5. Work our mean number of organisms per quadrat (total no. divied by total no. of quadrats.)
6. Do in second area and compare.
>If workout mean multiply by total area to find out population size of an organism in one area.
34
Transects
>Use transects to study the distribution of organisms along a line.
1. Mark out a line in the area you want to study using a tape measure.
2. Then collect data along the line.
3. You can do this by counting all the organisms you're interested in that touch the line.
4. Or, you can collect data using quadrats. These can be placed next to each other along the line or at intervals.
>Estimate percentage cover of a quadrat by counting squares with more than half covered with organism and divide by total then divide by 100.
35
impact of environmental changes on the distribution of species in an ecosystem
Environmental changes affect the distribution of species in an ecosystem. These changes include:
• temperature
• availability of water
• composition of atmospheric gases.
The changes may be seasonal, geographic or caused by human interaction.
E.g. rise in temp caused by global warming caused by human activity.
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environmental changes + distribution - availability of water
>Distribution of some animal and plant species in the tropics changes between the wet and dry seasons - time when more or less rainfall - more/less water available.
>E.g. Africa each year, large no. of giant wildebeest migrate, moving north + then back south as rainfall patterns change.
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environmental changes + distribution - temperature
>Distribution of bird species in Germany is changing due to rise in av. temp.
>E.g. European bee-eater bird is a Mediterranean species but is now present in parts of Germany.
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environmental changes + distribution - composition of atmospheric gases
>Distribution of some species changes in areas where there is more air pollution.
>E.g. some species of lichen can't grow in areas where Sulfur dioxide is given out by certain industrial processes.
39
How is water endlessly recycled?
>The water cycle provides fresh water for plants and animals on land before draining into the seas.
>Water is continuously evaporated and
precipitated.
>So its being endlessly recycled.
40
Water cycle
1. Evaporation due to Sun's energy. And transpiration from plants.
2. Warm water vapour carried up, cools plus condenses into clouds.
3. Precipitation. Feeds plants animals.
4. Drains into sea.
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Recycling
All materials in the living world are recycled to provide the building blocks for future organisms.
E.g. water cycle and carbon cycle
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Carbon cycle - basic
>The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.
>Role of microorganisms in cycling materials through an ecosystem by returning carbon to the atmosphere
as carbon dioxide and mineral ions to the soil.
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Carbon cycle - steps
1. CO2 removed in photosynthesis + used to make glucose, carbs, fats and proteins etc.
2. When plants+algae respire some is returned to atmosphere.
3. When plants are eaten by animals some carbon becomes part of fats+proteins in animals body. So carbon moves through food chain.
4. Animals respire - some returned to atmosphere as CO2.
5. When animals, plants+algae die detritus feeders and microorganisms feed on their remains. When these respire CO2 is returned to atmosphere.
6. Animals produce waste - broken down by detritus feeders + microorganisms.
7. Combustion also releases CO2 into atmosphere.
8. So carbon is constantly recycled.
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Food chains - recycling
>Elements are cycled back to start of food chain by decay. See book.
45
compost
>Compost is decomposed organic matter that is used as natural fertilisers for crops and garden plants.
>Gardeners and farmers try to provide optimum conditions for rapid decay of waste biological material. >The compost produced is used as a natural fertiliser for growing garden plants or crops.
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Optimum conditions for decay - list
>Microorganisms that are responsible for decomposition (decay) work best in certain conditions:
1. Temp
2. Oxygen availability
3. Water availability
4. No. of decay organisms.
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Optimum conditions for decay - temp
>Warmer temps - decmopose quicker as increase rate of enzyme activity involved in the decomposition.
>tOO hot - denature - decomposition slows down or stops as enzymes destroyed+organism dies.
>Too cold - slows rate too.
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Optimum conditions for decay - - o2 availability
>Many organisms need oxygen to respire, which they need to do to survive.
>The microorganisms involved in anaerobic decay don't need oxygen though.
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Optimum conditions for decay - water availability
>Decay takes place faster in moist environments as organisms involved in decay need water to carry out biological processes.
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Optimum conditions for decay - number of decay organisms
>The more microorganisms and detritus feeders there are, the faster decomposition happens.
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By-product of anaerobic decay
>Anaerobic decay produces methane gas.
| >Biogas generators can be used to produce methane gas as a fuel.
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Biogas
>Microorganisms decay plant+animal waste anaerobically, which produces methane gas.
>Biogas is mainly made up of methane which can be burned as a fuel.
>Biogas is made in a simple fermenter called digester or generator, which need to be kept at constant temp to keep aerobic microorganisms away.
>Biogas can't be stored as liquid as needs too high pressure - used straight away - heating, cooking, lighting.
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Biogas generators - types
>batch generators or continuous generators.
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batch generator
>Make biogas in small batches.
| >Manually loaded up with waste, which is left to digest, and the by-products are cleared away at end of each session.
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Biogas generators
1. inlet for waste material to be put in
2. outlet for digested material to be removed through
3. outlet so biogas can be piped out where it is needed.
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Continuous generators
>Make biogas all the time.
>waste is continuously fed in, and biogas is produced at a steady rate.
>continuous generators are more suited to large-scale biogas projects.
57
Investigating decay
>investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change.
>see book
58
Biodiversity - definition
Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem.
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WHY is biodiversity important?
>A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.
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Human impact on biodiversity
>The future of the human species on Earth relies on us maintaining a good level of biodiversity. Many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction.
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Human activities that affect biodiversity
>waste production
>deforestation
>increasing standard of living - food miles - want stuff quicker
>increasing pop - more demand - more pressure on environment - raw materials
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why has population risen?
>modern medicine and farming methods, which have reduced no. of peeps dying from disease and hunger.
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Human impact on biodiversity - waste production
1. water: sewage+toxic chemicals from industry can pollute lakes, rivers and oceans, affecting the plants and animals that rely on them for survival (including humans). And the chemicals used on lands (pesticides, fertilisers, herbicides) can be washed into water.
2. air: smoke+acidic gases released into atmosphere can pollute air, e.g. sulfur dioxide - acid rain.
3. land: use toxic chemicals for farming -pesticides +herbicides. also bury nuclear waste underground and dump household waste in landfill sites.
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pollution
>Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more
waste is produced. Unless waste and chemical materials are properly handled, more pollution will be caused.
>Pollution can occur:
• in water, from sewage, fertiliser or toxic chemicals
• in air, from smoke and acidic gases
• on land, from landfill and from toxic chemicals.
>Pollution kills plants and animals which can reduce biodiversity.
65
why is global warming speeding up?
>Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’.
66
global warming steps
1. temp of earth is a balance between energy it gets from sun and energy it radiates back out to space.
2. gases in atmosphere act as insulating layer, absorbing energy usually radiated back to space and re-radiates it back to earth's surface - temp increases.
3. if didn't have then nothing to keep energy in + would be too cold, but now its too thick.
4. increase in greenhouse gases - increase in global warming
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global warming - definition
>Global warming is a type of climate change and causes other types of climate change, e.g. changing rainfall patterns.
>Earth is gradually heating up due to increasing levels of greenhouse gases.
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Consequences of global warming
1. higher temp- seawater expands+ice melts - sea level rises - flooding in low-lying places - loss of habitats where organisms live.
2. increase in temp+change in rainfall - distribution of species. some will thrive over wider area - increase in pop others will become less widely distributed as conditions they thrive in e.g. the cold exist in smaller areas.
3. changes in migration patterns e.g. birds further north.
4. biodiversity could be reduced if some species are unable to change in the climate, so they become extinct.
69
Why has deforestation increased
>Large-scale deforestation in tropical areas has occurred to:
• provide land for cattle and rice fields - more food.
• grow crops for biofuels based on ethanol.
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why is human land use a problem?
>Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.
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consequences of deforestation
1. less CO2 taken in: less trees- less photosynthesis - they also 'lock up' carbon in their wood. release causes global warming which leads to climate change.
2. more co2 in atmosphere: co2 released when burnt to clear land + microorganisms which feed on dead wood release co2 as waste product of respiration.
3. less biodiversity: forests have huge no. of species, danger of extinction.
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Peat bogs
>The destruction of peat bogs, and other areas of peat to produce garden compost, reduces the area of this habitat and thus the variety of different plant, animal and microorganism species that live
there (biodiversity).
>The decay or burning of the peat releases carbon dioxide into the atmosphere. As they dead plants in peat contain carbon and some microorganisms start to decompose it when peat is drained and comes into contact with air - microorganisms use oxygen and release co2.
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reducing human effects on environment
>Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.
These include:
• breeding programmes for endangered species
• protection and regeneration of rare habitats
• reintroduction of field margins and hedgerows in agricultural areas
where farmers grow only one type of crop
• reduction of deforestation and carbon dioxide emissions by some governments
• recycling resources rather than dumping waste in landfill.
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reducing human effects on environment - breeding programmes for endangered species
>help stop become extinct
>in captivity so species survives if dies in wild.
>individuals sometimes released into wild to boost or re-establish population.
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reducing human effects on environment - protection and regeneration of rare habitats
>protects species that live there, preserving ecosystem + biodiversity in area.
>rare habitats = mangroves, heathland + coral reefs.
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reducing human effects on environment - reintroduction of field margins and hedgerows in agricultural areas
>Field margins are areas of land around the edges of fields where wild flowers and grasses are left to grow.
>they provide a habitat for a wider variety of organisms than could survive in a single crop habitat.
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reducing human effects on environment - reduction of deforestation and carbon dioxide emissions by some governments
>introduce regulations and programmes to reduce emissions.
| >reduces increase in global warming.
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reducing human effects on environment - recycling resources rather than dumping waste in landfill.
>reduce amount of land taken over for land fill, leaving ecosystems in place.
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conflicting pressures affecting how biodiversity is maintained
>costs money (e.g. government pays farmers subsidies to reintroduce field margins or watching whether programmes to maintain biodiversity are being maintained.).
>cost to local people's livelihood - tree-felling industry unemployed, affects local economy if peeps move to find work.
>food security - pests killed to protect crops+livestock so food chain+biodiversity affected.
>development, e.g. housing developments on biodiverse land or new agricultural land.
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What can food chains be divided into?
Trophic levels
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trophic level - definition
>Trophic levels are the different stages of a food chain.
| >They consist of one or more organisms that perform a specific role in the food chain.
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trophic levels
>Trophic levels can 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.
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Different levels list - trophic levels
>Level 1: Plants and algae make their own food and are called producers. Use sun's energy.
Level 2: Herbivores eat plants/algae and are called primary consumers.
Level 3: Carnivores that eat herbivores are called secondary consumers.
Level 4: Carnivores that eat other carnivores are called tertiary consumers. Apex predators are carnivores with no predators - always in highest trophic level.
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Decomposers
>Decomposers such as bacteria and fungi play an important role in ecosystems.
>They decompose any dead plant or animal material left in an environment.
>Decomposers break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the microorganism.
85
Pyramids of biomass
>Pyramids of biomass can be constructed to represent the relative amount of biomass in each level of a food chain. Basically how much all organisms would weigh.
>Trophic level 1 is at the bottom of the pyramid.
>Less energy and less biomass each time you move up a stage.
86
Loss of biomass between each trophic level
>Producers are mostly plants and algae which transfer about 1% of the incident energy from light for photosynthesis.
>Only approximately 10% of the biomass from each trophic level is transferred to the level above it.
>Losses of biomass are due to:
• not all 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 to provide energy for movement and keeping warm rather than to make more biomass.
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How to calculate efficiency of biomass transfer
(biomass transferred to next level divided by biomass available at previous level) x 100.
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Food security - definition
>Food security is having enough food to feed a population.
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Factors affecting food security
>Biological factors which are threatening food security include:
• the increasing birth rate has threatened food security in some countries.
• changing diets in developed countries means scarce food resources are transported around the world.
• new pests and pathogens that affect farming.
• environmental changes that affect food production, such as widespread famine occurring in some countries if rains fail - loss of crops - widespread famine.
• the cost of agricultural inputs makes it too expensive for some to start or maintain food production.
• conflicts that have arisen in some parts of the world which affect the availability of water or food.
>Sustainable methods must be found to feed all people on Earth.
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Sustainable production - definition
>Sustainable production means making enough food without using resources faster than they renew.
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Efficiency of food production
>The efficiency of food production can be improved by restricting energy transfer from food animals to the environment.
>This can be done by limiting their movement (Factory farmed in cages - livestock and fish) and by controlling the temperature of their
surroundings.
>Some animals are fed high protein foods to increase growth.
92
Efficiency of food production - cons
>Controversial.
>Ethical objections, unnatural and uncomfortable conditions is cruel.
>Disease can spread between them easily.
93
Overfishing
>Fish stocks in the oceans are declining as we are fishing so much.
>It is important to maintain fish stocks at a level where breeding continues or certain species may disappear altogether in some areas.
>This is sustainable food production.
94
How to maintain fish stocks
>Control of net size and the introduction of fishing quotas play important roles in conservation of fish stocks at a sustainable level.
>Net size - reduces no. of discarded fish and younger fish slip through allowing them to reach breeding age.
>Fishing quotas -Limits no. and size of fish that can be caught in certain areas - prevents certain species from being overfished.
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Biotechnology
>Modern biotechnology techniques enable large quantities of microorganisms to be cultured for food.
>Large amounts of microorganisms can be cultures industrially under controlled conditions in large vats for use as a food source.
96
Mycroprotein
>The fungus Fusarium is useful for producing mycoprotein, a protein-rich food suitable for vegetarians.
>The fungus is grown on glucose syrup, in
aerobic conditions, and the biomass is harvested and purified.
97
Human insulin - basic
>Bacteria can be engineered to produce human insulin.
>A genetically modified bacterium produces human insulin. When harvested and purified this is used to treat people with diabetes.
98
Genetic engineering - definitioin
>Transferring a useful gene from one organism to another.
99
Steps of producing human insulin
1. plasmid removed from a bacterium.
2. insulin gene is cut out of a human chromosome ring using a restriction enzyme. Reaction enzymes recognise specific sequences of DNA and cut the DNA at these points. The cut leaves one of the DNA strands with unpaired bases - this is called a stick end.
3. Plasmid is cut open using the same restriction enzyme - leaving the same sticky ends.
4. the plasmid and human insulin are mixed together.
5. Ligase is added. This joins the sticky ends together to produce recombinant DNA (2 different bits of DNA stuck together).
6. The recombinant DNA is inserted into a bacterium.
7. The modified bacterium is grown in a vat under controlled conditions. You end up with millions of bacteria that produce insulin. The insulin can be harvested and purifies to treat people with diabetes.
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Genetically modified crops
>Mostly happens in developing countries.
| >GM crops could provide more food or food with an improved nutritional value such as golden rice.
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biotechnology GM crops - pros
1. GM crops can be produced that are resistant to pests - improving crop yields.
2. They can be genetically modified to grow better in drought conditions - again improving crop yields.
3. And some crops can be modified to provide more nutritional value, e.g. 'Golden Rice' has been genetically engineered to produce a chemical that's converted in the body to vitamin A.
102
biotechnology GM crops - cons
1. Many people argue that people go hungry because they can't afford to buy food, not because there isn't food about. So they argue you need to tackle poverty first.
2. There are fears that countries may become dependent on companies who sell GM seeds.
3. Sometimes poor soil is the main reason why crops fail, and even GM crops won't survive.
