Ecology. AQA Biology topic 7

Transcription

1 Ecology AQA Biology topic 7

2 7.1 Adaptations, Interdependence and Competition

3 Ecosystems 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:

4 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) Get off my land In order to survive and reproduce, organisms require a supply of materials from their surroundings and other organisms, e.g. Yum!

5 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.

6 Abiotic Factors Scientists measure lots of abiotic factors, such as: Recording temperature changes Measuring rainfall Recording oxygen levels Other examples: Light intensity Soil ph and mineral content Wind strength and direction Carbon dioxide levels Oxygen levels in water

7 Effect of changing Abiotic Factors 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?

8 Biotic Factors Biotic factors affecting an ecosystem can include: Availability of food Arrival of new predators New pathogens/diseases One species being outcompeted Yum! Yum Harsh

9 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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16 Extreme environments What adaptations would be useful for these environments? Mountains Organisms living in these conditions are called extremophiles. Bacteria near deep sea vents are examples. The Arctic Deep sea volcanic vents

17 7.2 Organisation of an Ecosystem

18 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 Plants convert the sun s energy into food The arrows indicate where the energy is going Where did all of the energy in this chain come from in the first place?

19 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.

20 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

21 Food chains We can label the different consumers in a food chain: Producer Herbivore (primary consumer) Secondary consumer Top carnivore (tertiary consumer) Cabbage Rabbit Stoat Fox

22 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

23 Predators and Prey A PREDATOR is an animal that hunts and eats another animal The PREY is the animal it eats, for example Prey Hey! I ordered a steak Predator Consider the populations of these two animals over time: Population of animal Rabbit Time Fox

24 The Carbon Cycle CO 2 in air 2. Plants and algae release CO 2 through respiration 6. These microbes also release CO 2 through respiration 4. Animals release CO 2 through respiration 1. CO 2 is taken in by plants and algae for photosynthesis 5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders 3. The carbon taken in by plants is then eaten by animals and the animals that eat them

25 The Water Cycle 1. Condensation 3. Precipitation 4. Flow 2. Evaporation

26 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?

27 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 40 O C. 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

28 Biological Decay example - Milk 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

29 Biological Decay example - Milk

30 Compost bins 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.

31 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.

32 How Biogas Generators work Waste material in Gas comes out Anaerobic decay produces methane gas in here. What would be the optimum temperature?

33 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 2) Air pollution lichens, for example, don t like polluted air: Lichens in very clean air Lichens in slightly dirty air 3) Migration again, but this time for water: Are these changes caused by geographical reasons, humans or seasonal changes?

34 7.3 Biodiversity and the effect of human interaction on ecosystems

35 Biodiversity The world is populated by millions of different species of animals and plants and they all look and behave differently this is BIODIVERSITY

36 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.

37 What problems do these next pictures show?

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40 Waste Management The human population is growing exponentially: Population This has a number of effects on the environment: Time On land from landfill and toxic chemicals In air from smoke and acidic gases Pollution can occur In water from sewage, fertiliser and toxic chemicals Pollution kills plants and animals, which reduces biodiversity.

41 Land Use Q. How do humans reduce the amount of land available for plants animals? Farming Quarrying Building new homes Dumping waste

42 Peat Bogs 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

43 Deforestation 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

44 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

45 Carbon Dioxide and Global Warming Global levels of Carbon Dioxide in PPM Is there a link?

46 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 CO 2 ) 2) (removing trees that remove CO 2 ) 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

47 Potential Effects of Global Warming 1. Less farmland 2. Melting ice caps 3. Flooding of low land 4. Extreme weather

48 Maintaining Biodiversity Scientists and concerned citizens have put in place programs to reduce the negative effects of humans on ecosystems and biodiversity. Some examples: 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 CO 2 emissions 5) Recycling instead of using landfill sites

49 7.4 Trophic Levels in an Ecosystem (Bio only)

50 Numbering Trophic Levels Recall our food chain: Producer Herbivore (primary consumer) Secondary consumer Apex carnivore (tertiary consumer) Cabbage Rabbit Stoat Fox Level 1 - Producers Level 2 Herbivores that eat producers Level 3 Carnivores that eat herbivores Level 4 Carnivores that eat other carnivores

51 Decomposers Microorganisms are called decomposers. They are used by humans to help the decay process in compost heaps and sewage treatment works. Decomposers break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then pass into the microorganism.

52 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 4 - Mass of foxes Level 3 - Mass of stoats Level 2 - Mass of rabbits Level 1 - Mass of cabbages

53 Energy flow in a food chain Consider the energy flow in this food chain: 100% 10% 1% 0.1% Cabbage Rabbit Stoat Fox 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 CO 2 and water loss Words 10%, move, sun, waste, cabbage, 1%

54 An example calculation What is the efficiency at each stage of this food chain? 37kg 3.2kg 0.45kg 0.04kg Cabbage Rabbit Stoat Fox Efficiency = Biomass transferred to the next level Biomass available at the previous level 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?

55 7.5 Food Production (Bio only)

56 Global Population Global Population Changes Q. What do you think the following graph would look like? 10,000BC 8,000BC 6,000BC 4,000BC 2,000BC AD

57 Global Population Changes Statistics from Wikipedia: The world s population is currently growing by 1,000,000,000 people every years

58 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: Increased birth rate Changing diets more need to transport food. New pests and pathogens affecting farming Biological factors affecting food security Famine Cost of farming techniques Conflicts around the world We need sustainable methods of food production!

59 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 Fox 2) Limit an animal s movement or keep it warm: 3) Feed animals lots of protein to increase growth

60 Sustainable Development Sustainable development is all about preserving the world for tomorrow. The main point is don t use resources at a rate quicker than they are made. For example, don t fish too much! 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

61 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

62 Genetically Modified Foods Advantages 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 Disadvantages 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