24/10/2015 Understanding Our Environment W Richards The Weald School (OCR)

24/10/2015 Taking Population Samples Using different “sampling techniques” we can measure the population in a given area, for example: Using trapsTaking animal samples Help! Taking samples using quadrats Help!

24/10/2015Ecosystems An “Ecosystem” is a physical environment with a particular set of organisms living in it. They can be natural, e.g. a woodland, or artificial, e.g. a greenhouse. A natural ecosystem with high “biodiversity” An artifical ecosystem – biodiversity will be controlled and low

24/10/2015Classification The world is populated by millions of different species of animals and plants…

24/10/2015 Classifying organisms All organisms are classified into groups. For example: Organism PlantsAnimals VertebratesInvertebrates ReptilesFishBirdsMammalsAmphibians

24/10/2015 Classification Difficulties Some organisms do not fit into an obvious category. For example... Mushrooms Archaeopteryx

24/10/2015Variation “Species” means “a group of similar organisms”, e.g. dogs:

24/10/2015 Reproduction between species Liger GeepZebroid Mule

24/10/2015 Similar Species What is a common ancestor?

24/10/2015Photosynthesis PHOTOSYNTHESIS is when a plant makes its own food. Photosynthesis USES: Carbon dioxide Water Energy (from the sun) Photosynthesis PRODUCES: Oxygen Glucose

24/10/2015Photosynthesis Travels up from the roots WATER CARBON DIOXIDE Enters the leaf through small holes on the underneath SUNLIGHT Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen

24/10/2015 Photosynthesis Equations Carbon dioxide + _____ glucose + _____ 6CO 2 + 6H 2 0C 6 H 12 O 6 + 6O 2 Sunlight Chlorophyll Sunlight Chlorophyll The GLUCOSE produced by photosynthesis is used by the plant for _______ (through ____________). It is stored in the plant as ___________. Words – respiration, starch, water, oxygen, energy

24/10/2015 Factors Affecting Photosynthesis 1.Temperature – the best temperature is about 30 0 C – anything above 40 0 C will slow photosynthesis right down 2.CO 2 – if there is more carbon dioxide photosynthesis will happen quicker 3.Light – if there is more light photosynthesis happens faster

24/10/2015 Drawing graphs of these factors 1. Temperature Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 45 0 C 2. Carbon dioxide 3. Light Photosynthesis increases at first but is then limited by a lack of increase in temp or CO 2 Photosynthesis increases at first but is then limited by a lack of increase in temp or light

24/10/2015 What is the glucose used for? 1) Glucose (sugar) can be used to make long chains of insoluble starch… Glucose molecules Starch molecule 2) Glucose can be used to make cellulose for cell walls… 3) Glucose can be combined with nitrates to make proteins (for growth)… 4) Glucose can be converted into lipids (fats or oils) to store in seeds… Glucose molecules Cellulose Proteins Lipid structure

24/10/2015Respiration As well as photosynthesis, plants also undergo respiration: The plant uses this energy to work, grow and reproduce. Glucose + oxygen water + carbon dioxide + ENERGY

24/10/2015Competition Any living species competes with each other. They may compete for: - Living space - Food - Water In addition to this competition, the population of a species can be affected by predators, disease, migration etc Get off my land Yum!

24/10/2015 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

24/10/2015 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

24/10/2015 Interdependent Relationships 1) Parasitic relationships 2) Mutualistic Relationships Parasites take food from another living host _______. For example, if a human eats pork infected with bladderworm the worms attach themselves to the ___ wall and a young tapeworm grows, which _______ food from the gut. Mutualistic relationships are when two organisms benefit from each other. For example, pea plants have nitrogen-fixing ______ which convert nitrogen into nitrates for plant _____. The bacteria benefit by taking sugars from the plant for ___________. Words – growth, respiration, organism, gut, bacteria, absorbs

24/10/2015Adaptation Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:

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Evolution Charles Darwin ( ) Evolution is the slow, continual change of organisms over a very long time. All living things on the Earth have developed from the first simple life forms that arrived 3,000,000,000 years ago.

24/10/2015Evolution My key observations: 1)All living things produce more offspring than survive to adulthood 2)In spite of this, population sizes remain roughly constant 3)Variation exists among species 4)Characteristics can be passed on from one generation to the next. These observations led me to the conclusion that species evolve over a along period of time by a mechanism called “Natural Selection”. The main evidence for this is from fossil records.

24/10/2015 Natural Selection 1) Each species shows variation: 2)There is competition within each species for food, living space, water, mates etc 4)These survivors will pass on their better genes to their offspring who will also show this beneficial variation. Get off my land Gutted! Yum 3)The “better adapted” members of these species are more likely to survive – “Survival of the Fittest”

24/10/2015 Darwin vs Lamarck Darwin wasn’t the first to come up with evolution – he was simply the one credited with explaining how it worked (i.e. Natural Selection). An earlier scientist called Lamarck explained evolution by different means: Jean Baptiste Lamarck ( The giraffe has a long neck because it “stretches” its neck to reach the food, and these long necks are passed on to their offspring. Organs which aren’t used will eventually disappear.

24/10/2015 An example – the peppered moth

24/10/2015 A smaller example… Consider the four steps of natural selection in the example of some bacteria that has become resistant to penicillin: 1)Variation – some strains of bacteria are resistant and some aren’t. 2)Competition – The non-resistant bacteria are killed by the penicillin. 3)Survival of the fittest – the resistant bacteria survive. 4)Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring. Bacteria Penicillin

24/10/2015 The “Evolution Tree” Family Hominidae (Great Apes) Family Hylobatidae (Lesser Apes) Subfamily Hominidae Subfamily Ponginae Tribe HominiTribe Panini Tribe Gorillini HumansChimpanzeesGorillasOrangutansGibbons

24/10/2015 Evidence for Evolution The Grand Canyon Fossil records “Missing links” Humans with tails

24/10/2015 Population and Pollution The human population is growing exponentially: Population Time This has a number of effects on the environment: Bigger population means… Building – more buildings needed Land – less land and water available Waste – more waste needs to be disposed of with more pollution Quarrying and mining – raw materials and sources of energy are being used up

24/10/2015Ozone Diagram showing the quantity of ozone in different parts of the southern hemisphere Global production of CFCs over the last 60 years

24/10/2015Pollution Humans pollute the Earth in a number of ways: Water – with sewage, fertiliser or toxic chemicals Air – with smoke or gases such as sulphur dioxide Land – with toxic chemicals, pesticides and waste NO, NO 2 and CO Acid rain Power stations produce CO 2, SO 2 and NO 2 Cars produce NO, NO 2 and CO These gases produce acid rain (which affects tress and buildings) and worsens the greenhouse effect

24/10/2015 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

24/10/2015 Pollution Indicators Lichens in very clean air Lichens in clean air Lichens in slightly dirty air Lichens can be used as air pollution indicators:

24/10/2015 Pollution Indicators In dirty water leeches and midges will survive In average water more species (like the dragonfly and cranefly) will survive In clean water a lot more species (like the mayfly and caddisfly) will survive The quality of water can be monitored by looking at the species of insect in the water:

24/10/2015 Sustainable Development Sustainable development is all about preserving the world for tomorrow. There are three main strands: 1)Economic development 2)Social development 3)Environmental protection Examples of sustainable development include: 1)Replanting trees after chopping them down 2)Limiting the number of fish allowed in a catch 3)Protecting endangered species

24/10/2015 Extinct Species Dodo Sabre-toothed tigers and mammoths

24/10/2015 Endangered Species

24/10/2015 Protecting Endangered Species Ways of protecting endangered species