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1. Biodiversity and Human Impacts 2. Sampling Techniques 3. Energy Flow 4. Evolution Topic 1 Biodiversity Key Terms Term Definition Biodiversity Variety of living organisms on Earth. Biomes Regions of our planet as distinguished by their similar climate, flora and fauna e.g. tundra Habitat Place an organism lives. Ecosystem Habitat + Community Community All the living organisms in an area. Population A group of living organisms of the one type e.g. dogs Species A group of living organisms which are able to interbreed to produce fertile offspring. Niche Description of organisms lifestyle/ Role it plays. Biodiversity • Biodiversity is the term used to describe the variety of living things in an ecosystem. • Various factors can affect the biodiversity within an ecosystem, some of which include; - Abiotic factors - Biotic factors - Human influences - Natural hazards • It is important that Biologists keep a close eye on Biodiversity as ecosystems are delicately balanced. Understanding Biomes Earth is divided into distinct climate zones called BIOMES. • Each biomes contains it’s own animals (fauna), plants (flora) and climate (temperature and rainfall). • Plants and animals within these biomes are specially adapted to survive in their surroundings. • • THINK! What animals/plants do you find in the tropical rainforest? Are these the same in the desert or the polar regions on earth? Discuss why! Niches •A NICHE is the term used to describe the lifestyle/ role that an organism plays within its ecosystem. • Factors to consider when describing a niche include: - How that particular organism affects/is affected by other things around it - How it survives/competes • NICHES OFTEN COME UP AS EXAM MCQs Human Influences: Air Pollution • Car exhaust fumes contain sulphur dioxide and nitrogen oxides (NOx gases) which combine with rain water to form acid rain. • THINK! Why is acid rain problematic? Discuss. Human Influences: Deforestation • Deforestation is the clearing of vast areas of natural forest without replanting replacement forests. • There are many severe consequences of deforestation: - habitat destruction for many organisms - low-lying downstream areas become flooded - reduced soil fertility of hillsides - higher levels of CO2 contribute to greenhouse effect (climate change) Human Influences: Intensive Agriculture • Farmers create conditions that favour one or two chosen kind of crop plants and thus reduce the natural biodiversity. • Farmers will do this by using: • Herbicides to kill other plants • Pesticides to kill pests that reduce crop value • Fertilisers that favour the chosen crop • Planting GM Crops • Remove hedges for easier harvesting Effect of Human Influences • Human activities, e.g. pollution, habitat destruction and over hunting, are to blame for the current wave of extinctions. • Currently, extinction is happening x400 than the natural rate • There are several different species threatened with extinction today including; Black Rhino Endangered Californian Condor California Condor Endangered Giant Panda Endangered Snow Leopard Endangered Blue Whale Endangered Tiger Mountain Endangered Gorilla Topic 2 Sampling Key Terms Abiotic Factors (Non-living factors) Temperature Light Intensity Biotic Factors (Living factors) Predation Disease Soil Moisture pH of Soil Grazing Food Availability Abiotic Sampling • Abiotic factors are the NON-LIVING components of any ecosystem. • Experimental sampling of abiotic factors requires good technique to avoid errors whilst using the equipment. • Just as with any experiment it is fundamental that the readings are Repeated for Reliable Results. Abiotic Sampling: Equipment and Errors Abiotic Factor Equipment Required Avoiding Error Temperature Leave thermometer to settle for a few minutes before taking a reading. Thermometer Experiment 1: Abiotic Sampling Light Intensity Light Intensity Meter Do not cast a shadow over the solar Take equipment into grounds and panel. Stand to the side when sample 3 differenttaking areas for readings. comparison. pH of Soil Soil pH Meter Wipe the probe clean between Note your results samples in your jotters. to prevent any cross contamination. Soil Moisture Soil Moisture Meter Wipe the probe clean between samples to prevent cross contamination. ERRORS/ PREVENTIONS OFTEN EXAM QUESTIONS Biotic Sampling: Equipment and Errors • Biotic factors are the LIVING components of any ecosystem. The method used to sample the organisms depends on the type of species being studied. • Experimental sampling of biotic factors requires good technique and set up of equipment to avoid errors. Biotic Sampling: Pitfall Traps • Pitfall traps are a simple method which is used to sample small invertebrates such as insects found in leaf litter/on the floor of woodland etc. is essential that the cup buriedSampling level with the soil Experiment 2:isBiotic surface andTake is wellequipment camouflaged with leafs. and into grounds • It Why is up it important to camouflage set your pitfall traps in the top of the cup? What othervarious problemsareas. might arise? Are there any types of insects which this method is NOT suitable We will return to them tomorrow for sampling? Discuss. • THINK! for the results. Biotic Sampling: Quadrats • For plants and animals which don't move much (i.e. limpets) quadrats are normally used to sample their numbers in an area. Experiment 3: Biotic Sampling • Quadrats must repeatedly thrown RANDOMLY in the Takebe equipment into grounds* and area for reliable results. sample the field with your • Sources ofquadrat. error include the difficulty in identifying the species present or not to include a Note and any deciding findings whether in your jotters. plant which*Weather is partially present in the grid. depending Biotic Sampling: Other Methods • Other ways of sampling living organisms that you should be aware of include; - Tree Beating - Tulgren Funnel - Transect - Water Net Topic 3 Energy Flow Key Terms Term Definition Herbivore Animal which only eats plants Omnivore Animal which eats both plants and other animals Carnivore Animal which only eats other animals Intraspecific Competition Competition between the SAME species Interspecific Competition Competition between DIFFERENT species Pyramid of Numbers Pictorial diagram showing the relative numbers of each organism in a food chain. Pyramid of Biomass Pictorial diagram showing the relative DRY MASS of each organism in a food chain. Pyramid of Energy Pictorial diagram showing the relative energy at each level in the food chain. Energy Flow: Food Chains • Food chains show the DIRECTION of energy flow from producer (green plants) to consumer. • Only • The 10% of energy is passed on at each level in a food chain. other 90% is used in cellular processes, movement, homeostasis (temperature regulation) and excreted as waste. Energy Flow: Food Webs • Food webs are different from food chains as they show intraspecific competition over food sources thus providing a more complete picture of the 4: Owl Pellet Dissection energyExperiment flow. Tease apart the owl pellet to find out what it has eaten! FOOD WEB EXAM QUs WILL ALWAYS ASK HOW ONE SPECIES AFFECT ANOTHER (BALANCE) Working with Pyramids • Pyramids are used by Biologists to highlight in a pictorial fashion what information they can gather about food chains. • Pyramids of numbers represent how many of each organism there are in one food chain whilst Pyramids of Biomass show the DRY mass of each organism in a food chain. • The shape of these pyramids often form a classic triangle however there are exceptions for number pyramids e.g. when parasites are present or when a large tree is the initial producer. Pyramid Shape Examples 1. Parasites Present 2. Tree as Producer 3. Classic Example Energy Flow: Nitrogen Cycle • It is essential that Nitrogen is recycled between food webs and the ecosystem (Circle of Life). • Nitrogen is needed to make PROTEINS but cannot be absorbed in gaseous form by plants or animals. • Plants must absorb Nitrogen in the form of NITRATES from the soil as shown in the Nitrogen cycle on the next slide. The Nitrogen Cycle Experiment 5: Root Nodules Prove that nitrifying bacteria can be found in root nodules by growing them on nitrogen free agar plates! Type of Bacteria Role in Nitrogen Cycle Decomposers Decompose (breakdown) the nitrogen found in dead bodies and waste into ammonium Convert ammonium into nitrites and then into nitrates Nitrifying Denitrifying Breakdown nitrates releasing nitrogen gas into the air Nitrogen Fixing ‘Fix’ nitrogen gas from the air into nitrates or protein Over Use of Fertilisers • Farmers often use fertilisers to increase the nutrients in their soil; particularly Nitrogen. • Many problems can arise due to fertiliser over-use; in particular EUTROPHICATION due to nutrients feeding bacteria and causing ALGAL BLOOMS which lead to DECREASED BIODIVERSITY. 4 MARK EXAM QU. MAKE SURE YOU KNOW THE NITROGEN CYCLE AND PROBLEMS!! Topic 4 Adapt, Nat Selection & Evolution Key Terms Term Definition Mutation A random change to genetic material (DNA) Adaptation An inherited characteristic that makes an organism suited to its environment Natural Selection Favourable alleles (genes) are passed on to the next generation. Evolution Changes which have occurred over long periods of time to develop new species from one common ancestor. Adaptations THINK! What are the ADAPTATIONS on the following examples? Are they STRUCTURAL/ BEHAVIOURAL? Example 1: Cactus Example 2: Polar Bear Adaptations • Adaptations can arise from a mutation which covets survival. • Mutations can be advantageous, neutral or disadvantageous. • The rate at which mutations appear can be affected by : 1. Exposure to high temperatures 2. Exposure to radiation 3. Exposure to chemicals. • THINK! Can you think of any mutations in humans which are advantageous/neutral or disadvantageous? Discuss. Natural Selection • Natural selection is when alleles (genes) which are favorable to the survival of the species are passed on to the next generation. • The classic example is the peppered moth in Britain: - White form original (1800s) - Industrial revolution - Soot covered trees - Mutation for colour arose - Black form survived predation - Decrease in pollution means both forms exist today Evolution (Speciation) • There are 4 key stages to the evolution of a species.