ecology...ecology aqa biology topic 7 7.1 adaptations, interdependence and competition 21/11/2017...
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Ecology AQA Biology topic 7
7.1 Adaptations, Interdependence and
Competition
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Ecosystems 21/11/2017
Definition: An “ecosystem” is the total interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
Different species can show competition within their ecosystem and can be adapted to their ecosystem. Some examples:
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Competition Any living species competes with each other within an ecosystem. They may compete for:
- Living space
- Food
- Water
- Access to nutriets and light (plants)
In order to survive and reproduce, organisms require a supply of materials from their surroundings and other organisms, e.g.
Get off my land
Yum!
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A simple example of interdependence
Consider oxpeckers and buffalo:
This is an example of “interdependence” – the idea that different species depend on other species for food, shelter, seed dispersal etc. If one species is removed it can affect the whole ecosystem.
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Abiotic Factors
Recording temperature changes
Measuring rainfall Recording oxygen levels
Scientists measure lots of abiotic factors, such as:
Other examples:
• Light intensity • Soil pH and mineral content • Wind strength and direction
• Carbon dioxide levels • Oxygen levels in water
Effect of changing Abiotic Factors 21/11/2017
Here are some abiotic factors again:
• Temperature • Moisture levels • Light intensity • Soil pH and mineral content
• Wind strength and direction • Oxygen levels in water • Carbon dioxide levels
Q. How would an increase in any of these factors affect these organisms?
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Biotic Factors Biotic factors affecting an ecosystem can include:
• Availability of food
• Arrival of new predators
• New pathogens/diseases
• One species being outcompeted
Yum!
Harsh
Yum
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Adaptation
Organisms are ADAPTED to the habitat and ecosystem they live in. In other words, they have special features that help them to survive. These adaptations may be structural, behavioural and functional.
Here are some examples of adaptations. For each one, is it structural, behavioural or functional?
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Extreme environments
Deep sea volcanic vents
Mountains
The Arctic
What adaptations would be useful for these environments?
Organisms living in these conditions are called “extremophiles”. Bacteria near deep sea vents are examples.
7.2 Organisation of an Ecosystem
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Food chains
A food chain shows where the energy goes in a food chain (in other words, “what gets eaten by what”):
Cabbage Rabbit Stoat Fox
The arrows indicate where the energy is going
Plants convert the sun’s energy into food
Where did all of the energy in this chain come from in the first place?
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Plants in food chains Here’s the food chain again:
Cabbage Rabbit Stoat Fox
Notice that food chains start with plants. Plants are called “producers” – they “produce” the energy (glucose) for the rest of the food chain through photosynthesis. Producers at the start of a food chain are usually plants or algae.
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Using Quadrats That’s a nice ecosystem. I think I’ll sample it using my
quadrat. How do I do it?
1) Lay down a transect line
2) Mark off regular intervals, e.g. 1m
3) Use the quadrat every metre to sample the population size of different organisms
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Food chains We can label the different consumers in a food chain:
Cabbage Rabbit Stoat Fox
Producer Herbivore (primary
consumer)
Secondary consumer
Top carnivore (tertiary
consumer)
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Match these words… Tertiary
consumer
Herbivore
Top carnivore
Producer
Secondary
consumer
Consumer
Omnivore
Carnivore
Primary
consumer
Usually plants. Starts off a food chain
Animals that only eat plants
An animal that eats producers
An animal that eats primary consumers
An animal that eats secondary consumers
A general word for “an eater”
Eats only animals
Not eaten by anything else
Eats both animals and plants
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Predators and Prey A PREDATOR is an animal that hunts and eats another animal
The PREY is the animal it eats, for example…
Consider the populations of these two animals over time:
Hey! I ordered a
steak
Population of animal
Time
Rabbit
Fox
Prey Predator
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The Carbon Cycle
CO2 in air
1. CO2 is taken in by plants and algae for photosynthesis
2. Plants and algae release CO2 through respiration
3. The carbon taken in by plants is then eaten by animals and the animals that eat them
5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders
6. These microbes also release CO2 through respiration
4. Animals release CO2 through respiration
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The Water Cycle
1. Condensation
2. Evaporation
3. Precipitation
4. Flow
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Decomposition (Bio only)
Microbes are the key to this – they break down waste and dead bodies so that the products can be used by plants for growth. Microbes work best in conditions that are:
1) Warm
2) Moist
3) High in oxygen
Can you explain why these conditions help?
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More about Decay Decay is the process of breaking down complex structures into ______ ones. This is done be micro organisms.
The rate of decay is affected by the _______ of these microorganisms:
1) Temperature – the micro organisms’ rates of growth and respiration are quickest at around 40OC. They become “_________” at temperatures higher than this.
2) Oxygen – more oxygen means _____ micro organisms.
3) Water – micro organisms grow quickest in ______ conditions.
Bacteria and fungi are called “saprophytes” – they feed on dead organic material by secreting _______ and then absorbing the digested products.
Words – enzymes, more, moist, simpler, growth, denatured
Biological Decay example - Milk 21/11/2017
Here is an experiment where someone has investigated how the pH of milk has changed due to an enzyme, at different temperatures. Can you plot a graph of this data and calculate the rate of decay?
Rate = 1000 time
Biological Decay example - Milk 21/11/2017
Compost bins 21/11/2017
That’s a nice compost bin. What’s the point in having one?
Compost bins provide optimum conditions for rapid decay of waste biological material. The compost produced is used for fertiliser.
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Biogas Task: Find a diagram of a biogas generator and explain how it works. To do this you should include answers to the following questions:
1) What is the main part of biogas?
2) What process goes on inside the generator?
3) What raw materials go inside the generator and where do they come from?
4) What does the generator produce and what do you use these products for?
Extension – find out how different types of biogas generator are used in different conditions and why.
How Biogas Generators work 21/11/2017
Waste material in Gas comes out
Anaerobic decay produces methane gas in here. What would be the optimum temperature?
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Impact of Environmental Changes (Bio only) Changes in temperature, atmospheric gases and availability of water and food can cause the distribution of organisms in an environment to change. Some examples:
1) Migration – birds moving to a warmer climate
Lichens in very clean air
Lichens in slightly dirty air
2) Air pollution – lichens, for example, don’t like polluted air:
3) Migration again, but this time for water:
Are these changes caused by geographical reasons, humans or seasonal changes?
7.3 Biodiversity and the effect of human interaction on
ecosystems
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Biodiversity The world is populated by millions of different species of animals and plants and they all look and behave differently – this is BIODIVERSITY…
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Ecosystems and Biodiversity Here are two different ecosystems with different levels of biodiversity. Which one is better?
A natural ecosystem with high “biodiversity”
An artifical ecosystem – biodiversity will be low
A high biodiversity ensures the stability of an ecosystem by reducing the dependence of one species on another for food. The future of the human species depends on us maintaining a high biodiversity and many human activities have disrupted this.
What problems do these next pictures show?
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Waste Management
The human population is growing exponentially:
Population
Time
This has a number of effects on the environment:
Pollution can occur…
In water – from sewage, fertiliser
and toxic chemicals
On land – from landfill and toxic chemicals
In air – from smoke and
acidic gases
Pollution kills plants and animals, which reduces biodiversity.
Land Use 21/11/2017
Q. How do humans reduce the amount of land available for plants animals?
Quarrying Farming
Dumping waste Building new homes
Peat Bogs 21/11/2017
Here’s a peat bog:
This doesn’t look very interesting but peat bogs have a high amount of _______, so destroying peat bogs for things like ______ is bad news. Furthermore, the _____ or _______ of the peat releases ____ ______ into the atmosphere:
Words – carbon dioxide, biodiversity, decay, burning, compost
Deforestation 21/11/2017
Large scale deforestation to make space has been occurring in tropical areas. Why have humans been doing this and what problems has it caused?
Reasons: 1) Make space for cattle and rice fields 2) Grow crops for biofuels
Problems: 1) Less oxygen released into atmosphere 2) Less carbon dioxide taken in 3) Less biodiversity
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Upsetting the balance Until recently, the environment has maintained a balance in carbon dioxide:
Carbon dioxide is produced by respiration…
…and used by photosynthesis
Unfortunately, this balance is being upset by two main factors:
1) Excessive burning of fossil fuels…
…is producing too much carbon dioxide
2)Large scale deforestation…
…is slowing down the removal of carbon dioxide from the atmosphere
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Carbon Dioxide and Global Warming Global levels of Carbon Dioxide in PPM
Is there a link?
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The Greenhouse Effect We get heat from the sun:
A lot of this heat is _______ back into space.
However, most of it is kept inside the Earth by a layer of gases that prevent the heat escaping by _______ and then re-radiating it back again.
This is called the _________ Effect. It has always been around, but is currently being made worse due to:
1) Burning (releasing CO2)
2) __________ (removing trees that remove CO2)
3) Increased micro organism activity (from rotting ______)
4) Cattle and rice fields (they both produce _______)
These changes will cause GLOBAL WARMING and RISING SEA LEVELS
Words – methane, radiated, absorbing, deforestation, waste, greenhouse
Potential Effects of Global Warming 21/11/2017
1. Less farmland 2. Melting ice caps
3. Flooding of low land 4. Extreme weather
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Maintaining Biodiversity
1) Breeding programs for endangered species
2) Protection and regeneration of rare habitats
3) Reintroduction of field margins in farms where only one crop is grown
4) Reduction of deforestation and CO2 emissions
5) Recycling instead of using landfill sites
Scientists and concerned citizens have put in place programs to reduce the negative effects of humans on ecosystems and biodiversity. Some examples:
7.4 Trophic Levels in an Ecosystem (Bio only)
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Numbering Trophic Levels Recall our food chain:
Cabbage Rabbit Stoat Fox
Producer Herbivore (primary
consumer)
Secondary consumer
Apex carnivore (tertiary
consumer)
Level 4 – Carnivores
that eat other carnivores
Level 1 - Producers
Level 2 – Herbivores
that eat producers
Level 3 – Carnivores that eat
herbivores
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Decomposers
Decomposers break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then pass into the microorganism.
Microorganisms are called “decomposers”. They are used by humans to help the decay process in compost heaps and sewage treatment works.
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Pyramids of biomass In this food chain we can see that the mass of organisms in each stage is less than in the previous stage:
Cabbage Rabbit Stoat Fox
We can draw a “Pyramid of Biomass” to show this pattern:
Level 1 - Mass of cabbages
Level 2 - Mass of rabbits
Level 3 - Mass of stoats
Level 4 - Mass of foxes
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Energy flow in a food chain Consider the energy flow in this food chain:
Cabbage Rabbit Stoat Fox
100% 10% 1% 0.1%
Clearly, not all of the ___’s energy that becomes stored in the _______ will end up in the fox. Only around ______ is passed on to the next stage in each food chain. Producers only transfer ___ of light energy.
Energy is lost to the surroundings at each stage because of a number of reasons:
1) Each organism has to use glucose in respiration to ____, keep warm etc
2) Energy is lost through faeces (______) or through CO2 and water loss
Words – 10%, move, sun, waste, cabbage, 1%
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An example calculation What is the efficiency at each stage of this food chain?
Cabbage Rabbit Stoat Fox
37kg 3.2kg 0.45kg 0.04kg
Clearly, a fox doesn’t have a mass of 0.04kg. This number represents the amount of biomass available to it. How does this affect the numbers of organisms as you go up the levels in a food chain?
Efficiency = Biomass transferred to the next level
Biomass available at the previous level
7.5 Food Production (Bio only) 21/11/2017
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Global Population Changes
10,000BC 8,000BC 6,000BC 4,000BC 2,000BC 0 2000AD
Glo
bal
Pop
ulat
ion
Q. What do you think the following graph would look like?
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Global Population Changes Statistics from Wikipedia:
The world’s population is currently growing by 1,000,000,000 people every 10-15 years
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Food Security The human population is growing exponentially:
Population
Time “Food security” means “having enough food to feed the population”. Biological factors that are affecting food security are:
Biological factors
affecting food security
Famine Increased birth rate
Changing diets – more need to
transport food.
Cost of farming techniques
New pests and pathogens affecting farming
Conflicts around the world
We need “sustainable” methods of food production!
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Farming Techniques As we said before, food chains aren’t very efficient. How could the efficiency of a food chain be improved?
1) Reduce the number of stages in the chain:
Cabbage Rabbit Stoat
2) Limit an animal’s movement or keep it warm:
Fox
3) Feed animals lots of protein to increase growth
Protein
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Sustainable Development Sustainable development is all about preserving the world for
tomorrow.
Examples of sustainable development in fishing include:
1) Limiting the number of fish allowed in a catch (a “quota”)
2) Controlling the size of the net
The main point is – “don’t use resources at a rate quicker than they are made”. For
example, don’t fish too much!
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Fusarium fungus and Mycoprotein
Fusarium sp is a fungus used to make mycoprotein (a _______-rich food suitable for _________). The fungus is grown on glucose ______ under ________ conditions and the biomass is harvested and ________.
Words – aerobic, protein, vegetarian, syrup, purified
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Genetically Modified Foods Advantages Disadvantages
Improving crop yield
Improving resistance to pesticides
Extend shelf-life
Manufacture a certain chemical (e.g. insulin)
Convenience
Could be used to make a “super food”
Genetically modified organisms may be expensive
Unknown effects on ecosystems
Effects may be passed on to other crops, e.g. weed resistance spreading from crops to weeds
Ethical issues