Biology 7

Ecosystem= interaction of community of living organisms & non-livng parts of environment

To survive & reporduce organisms need supply of materials from surroundings & other organisms

Plants often compete for light, space, water or minerals

Animals compete for food, mates or territory

Species depend on other species for food, shelter, pollination, seed dispersal etc.

Interdependence= one species removed affect entire community

Stable community= species & environmental factors in balance (population size is constant)

Abiotic= non-living factors which affect a community

-light intensity

-temperature

-moisture levels

-soil pH & mineral content

-wind intensity & direction

-carbon dioxide levels for plants

-oxygen levels for aquatic animals

Biotic= living factors which affect a community

-availability of food

-new predators arriving

-new pathogens

-one species outcompeting another 

Adaptations= features in an organism to enable them to survive

Types of adaptations:

-structural

-behavioural

-functional

Extremophiles= organisms live in envrionments that are very extreme (high temp, pressure/salt conc)

-example= bacteria living in deep sea vents

Feeding relationships represented by food chains

-they have a producer with synthesising molecules (green plant/ algae)

Experimental method (transects & quadrats) used by ecologist to determine distribution & abundance of species in ecosystem

Producers are eaten by primary consumers

Primary consumers are eaten by secondary consumers 

Secondary consumers are eaten by tertiary consumers

Predators= consumers that eat & kill other animals

Stable envrionment= predators & prey rise & fall in cycles

All materials in living world are recycled to provide the building blocks for future organisms

Carbon cycle returns carbon from organisms into the atmosphere for photosynthesis

Water cycle provide water for plants & animals on lands

-water continuously evaporates & precipitates

Gardeners & farmers try to provide optimum conditions for rapid decay of waste biological material

Compost produced is used as a natural fertiliser

-used for plants & growing crops

Anaerobic decay produces methane gas

Biogas generators can be used to produce methane for fuel

Environmental change has an effect on the distribution of species in an ecosystem

-temperature

-availability of water

-composition of atmospheric gases

Changes may be:

-seasonal

-geographical

-human interaction

Biodiversity= variety of all different species of organisms on Earth/ within ecosystem

Greater biodiversity= stability of ecosystems

-reduces dependance on one species for food, shelter & maintainance of physical environment

Future of human species relies on good level of biodiversity

-human activity reduces biodiversity

Rapid growth of human population & increased standard of living= more resources used & more waste produced

-waste & chemical materials not properly handled= more pollution

Pollution can occur:

-water (sewage, fertiliser or toxic chemicals)

-air (smoke & acidic gases)

-land (landfill & toxic chemicals)

Pollution kills plants & animals (reduces biodiversity)

Humans reduce amount of land available

-building

-quarrying

-farming

-dumping waste

Destruction of peat bogs reduces area of habitat

-lower biodiversity

Decay/ burning of peat= release carbon dioxide into the atmosphere

Large-scale deforestation occurs for:

-provide land for cattle & rice field 

-grows crops for biofuels

Levels of carbon dioxide & methane in atmosphere increases

-contributes to Global Warming

Scientists & citizens have programmes to reduce negative effects

-humans have effect on ecosystem & biodiversity

This includes:

-breeding programmes (endangered species)

-protection & regeneration of rare habitats

-reintroduction of field margins & hedgegrowes

-reduction of deforestation & carbon dioxide emissions

-recycling resources rather than dumping in landfills

Trophic level represented by numbers

-futher levels numbered subsequently

Level 1: Plants & algae make their own food (producers)

Level 2: Herbivores eat plants/algae (primary consumers)

Level 3: Carnivores that eat herbivores (secondary consumers)

Level 4: Carnivores eat other carnivores (tertiary consumers)

-apex predators are carnivores with no predators

Decomposers break down dead plants & animals by secreting enzymes

-small soluble molecules diffuse into microorganisms

Pyramids of biomass= constructed to represent the relative amount if biomass in each level

-level 1 is bottom of pyramid

Producer (plant/algae) transfer 1% of energy from light to photosynthesis

10% of biomass transferred to each level

Losses of biomass:

-not all material ingested absorbed (some excreted)

-some absorved material is lost as waste

Large amoundt of glucose used for respiration

Food security= enough food to feed a population

Factors affecting FS:

-increasing birth rate

-changing diet (scarce food resources transported)

-new pests & pathogens

-environmental changes affecting food production

-costs of agricultural inputs

-conflicts arising in countries

Sustainable methods must be found to feed all people

Efficiency of food production can improve by;

-restricting energy transfer from food animals to envrionment

-limiting movement & controlling temp of surroundings

Some animals fed high protein foods (increase growth)

Fish stocks are declining

-maintaining levels for breeding or species may become extinct in areas

Control of net size & fishing quota for conservation of fish stocks at sustainable levels

Modern biotechnology--> enable large quatities of microorganism to be cultured for food

-fusarium= mycroprotein (protein rich food suitible for vegetarians)

-fungus grows in glucose syrup (aerobic conditons)

-harvested & purfied

GM bacterium produce insulin

-harvested & purified then used to treat diabetes

GM crops provide more food/ food with improved nutritional value