Unit F215 control, genomes and environment Module 3 Ecosystems and sustainability

Brain warm-up Productivity - Improving food production p6 Improving primary productivity why use greenhouses, fertilizers, pesticides, selective breeding or genetic modification? Improving secondary productivity why use selective breeding, steroid hormones or antibiotics? Why keep animals in sheds? Why chose fish rather than cows? To think about :- Should humans become vegetarians to help to solve the world food crisis?

Improving primary productivity why use greenhouses, fertilizers, pesticides, selective breeding or genetic modification?

Improving secondary productivity Some cows were kept in a field and others in a shed. Suggest which converted most energy into meat. food 1000 kJ  respiration  faeces+urine  meat

Decomposers p7 Some bacteria (prokaryote kingdom) + fungi (fungi kingdom) Saprophytes = heterotrophs feed on dead organic matter essential for recycling of minerals e.g. nitrogen Secrete enzymes  extracellular digestion e.g. hydrolysis of protein  amino acids e.g. hydrolysis of carbohydrate  glucose Small molecules diffuse into saprophyte Used for growth e.g. new protein or energy released by respiration

Nitrogen cycle animation ltimedia/index.php?Page=280http:// ltimedia/index.php?Page=280 gen_cycle.htmhttp:// gen_cycle.htm

Why do living organisms need nitrogen? and why don’t they use nitrogen gas in air? Nucleic acids DNA and RNA - the nitrogen is contained in bases (C, G, A, T) Proteins / amino acids - the nitrogen is contained in the amino group NH 2 Nitrogen gas in air is very unreactive = 2 nitrogen atoms held by a triple bond Nitrogen fixation converts the gas into a reactive molecule e.g. ammonium ions or nitrate ions

Stretch and challenge – nitrogen metabolism in plants

Checking your learning The roles of bacteria in the nitrogen cycle Type of bacteriaWhere foundRole Rhizobium Free-living bacteria Nitrogen fixation Nitrosomonas Nitrobacter Denitrification

What determines the size of a population? Key definitions A population is a group of organisms of the same species which live in the same place at the same time and can interbreed to produce fertile offpring. Carrying capacity is the maximum population size that can be maintained over a period of time in a particular habitat A limiting factor is the one which limits the rate of a natural process. Limiting factors for population size include food supply, breeding sites, predators and parasites. Applying your knowledge – choose a species of living organism and use the ideas in the 3 key definitions above to explain why there could be a large population in one area and a much smaller population of the same species in another area.

Suggested answer For rabbits:- The area with the larger population has a higher carrying capacity. There is better growth of small plants, suitable sandy soil for burrows and fewer foxes as predators because of actions taken by a farmer. The other area has soil which often becomes water logged so the plants grow more slowly and burrows are flooded. There are a similar number of predators but the rabbits have higher populations of parasites because of the damp conditions and lower quality food supply.

Colonisation of a new island Surtsey Island, near Iceland

Surtsey Island, near Iceland formed in 1963

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Surtsey Island, near Iceland colonised by plants and animals

More about Surtsey The Surtsey Society website – look at this for more details of the colonisation of Surtsey Stretch and Challenge Run the simulation of colonisation of new oceanic islands. Can you describe and explain what affects the species diversity on the islands?

Predator – Prey Interactions

Predator prey relationships _res/secondary/Costa%20Rica%20Learning%20 Objects/flash_predator-prey/predator-prey.htmlhttp:// _res/secondary/Costa%20Rica%20Learning%20 Objects/flash_predator-prey/predator-prey.html Moose + wolves atl/video.htmlhttp:// atl/video.html Ladybird invasion 30/harlequin-ladybird-uk-invasionhttp:// 30/harlequin-ladybird-uk-invasion

Predator and prey populations Can you see any relationship between these graphs?

Predator and prey populations

Fur trappers in the 1800s in Canada sold their pelts to the Hudson Bay Company. Careful records of numbers of Lynx and Snowshoe Hare produced the following graph.

Predator and prey populations Which has the larger population – predator or prey? Why? Which population increases first – predator or prey? Why?

Interspecific competition between 2 species of flour beetle Can you interpret the data on p14?

Intraspecific competition in limpets p15 what is the relationship between shell length and density? what is the carrying capacity of the environment?

Conservation and preservation p16 By the end of this section you should be able to:- distinguish between conservation and preservation explain how the management of an ecosystem can provide resources in a sustainable way with reference to timber production in a temperate country explain that conservation is a dynamic process involving management and reclamation discuss the economic, social, and ethical reasons for conservation of biological resources

Conservation or preservation? Preservation is the protection of an area by restricting or banning human exploitation or contact e.g nature reserves / preserves / parks. Conservation is maintaining biodiversity but allowing sustainable production e.g. replanting mixed tree species after clear felling for timber. Active Management is part of conservation e.g. by allowing herbivores to feed e.g. coppicing for timber Conservation is for economic (e.g. timber industry), social (e.g. recreation) and ethical (e.g. preventing species extinction) reasons. Examples include work on the Galapagos Islands

Coppicing – sustainable timber production which maintains biodiversity

Clear felling or selective felling – what are the advantages and disadvantages?

discuss the economic, social, and ethical reasons for conservation of biological resources p18