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