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Topic 9 (Abiotic factors that affect the distribution of organisms. (Light…
Topic 9
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Food web - shows feeding relationships between organisms in a community.
- food web help predict what will happen if there are changes in the ecosystem
1 st - producers
2nd - Primary consumer (herbivore)
3rd - secondary consumer carnivore predator
4th - tertiary consumer
5th - top predator
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Organism - Are individual animals, plants or singled cell life forms.
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Population size can be estimated by taking samples using a quadrat. Quadrats are placed randomly in the area and the number of individuals in each quadrat is counted.
Population size = number of organisms in all quadrats multiply total size of area where organisms live/total area of quadrat.
Abiotic factors - non living - temperature,rainfall + substances in the soil.
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Core practicle - Quadrats and Transects
- Peg out a long tape measure (at least 20m) on the ground, strating where there is no shade + ending in heavy shade. this is the transect line.
- make measuremenst at regular intervals along the transect line.
- place the top left hand corner of the quadrat at a measurement point on the transect line.
- measure the abiotic factors at the point + record them.
- record the abundance of your selected plants in the quadrat.
- Repeat back the steps.
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Biotic:
- After 1926 the number of Elk population increased + there was a huge number of overgrazing of many trees.
- This left a little food for herbivore : beavers.
- Elk + Beavers compete for food from trees.
- However, the number of coyotes increase because there was less competition from wolves for young Elks.
- In 1995, grey wolves were introduced to Yellowstone Park.
- The aim was to increase predation of elk.
- Reintroduction of wolves to to Yellowstone rapidly reduced the number of elks.
- led to an increase in the number of beavers .- Beavers change the surrounding by building dams, creating large pools + muddy areas.
- New habitats allowed new species to grow , increasing the biodiversity.
Parasitism - is a different kind of feeding relationship in which one organism (the parasite) benefits by feeding off a host organisms causing harm to the host.
Tape worms adaptations - live inside the host's intestine
- Hooks + suckers attach the worms head firmly to the hosts intestine wall.
- segments contain male + female sex organs so fertilisation can occur.
- flattened body allows absorption of nutrients over whole surface without need for digestive or circulatory systems.
Water Cycle
- Water evaporates from the ocean, lakes + rivers to form water vapors.
- As air rises it cools, water vapour in ti condenses to form clouds.
- Water droplets get heavier and falls as snow or rain.
- ground water - water moves from soil + rock and water and water leaves plants by evaporation.
- River flows into the lake + water return to the ocean.
Head lice adaptations - live on hair + skin
- Sharp mouth parts can pierce skin + suck blood.
- Sharp claws grip onto the skin + hair.
- Eggs are glued to hair prevent them from falling.
Mutualism - Organisms that live together both benefit from the relationship.
- e.g flowers depend on insects for pollination.
- Insects collect nectar or pollen from the flower, which it uses for food.
- Coral polyps form a special relationship with algae. algae photosynthesis + share the food they make with coral.
Fish Farming
- As human population increase , lead to overfishing
- Fish farming aims to produce more food + reduce overfishing of wild fish.
problems - many fish kept in small spaces.
- uneaten food + faeces sinks to the bottom of the water..
- this changes the conditions - harm wild organisms that live there.
- Parasites + diseases spread easily between fish , so need to be treated to keep them healthily.
Introducing species
- introducing new species affect the indigenous or native species.
- Species are introduced to control the number of other species.
- e.gs. toads from south americas
Eutrophication - addition of more nutrients to an ecosystem than it normally has
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- Fertiliser is added
- heavy rain washes off fertiliser off.
- Nitrates + phosphates dissolve in soil water.
- Nitrates + phosphates not taken up the plant are washed into stream or river.
- High nitrate + phosphate concentrations in water encourage plants + algae to grow rapidly .
- Surface plants block sunlight, so plants underneath die + stops photosynthesis.
- Bacteria that break down dead material increases + use up more oxygen from the water.
8.oxygen concentration of water decreases.
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Conservation - when an effort made to protect rare or endangered species or habitat.
Habitats are lost because - deforestation in the dense fores + hunting.
Preserving many species are important because: - food sources
60% are body is water + cell cytoplasm is water.
To make water portable(safe drinking water) - water must be treated with chemicals + filtered, to remove dirt, pathogens + toxic substances.
- Places where there is drought drinking water is collected from air or extracted from sea water.
- Desalination - Obtaining fresh water from sea water.
- Distillation - where the water evaporated + condensed + collected.
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- Carbon dioxide molecules in atmosphere diffuse into plant leaves . Inside leaf, photosynthesis cause carbon atoms in molecule to become part of another carbon compound called glucose.
- Glucose used by plants for respiration, carbon atom become part of carbon dioxide again + released back to atmosphere.
- Whilst, glucose changed into carbon compounds + used to make more plant biomass.
- Carbohydrates,fats + proteins in plants carbon atoms are contained. Animals eat plants + compounds are digested + taken into body + leaves animal body as faeces.
- Some absorbed carbon compounds used for respiration + some waste products excreted in urine.
Rest used to build up complex compounds in animals tissue, making more animal biomass.
- If species not eaten - decay occurs by decomposers, who are fungi + bacteria, which break down carbon compounds in animal waste.
- Decomposers use carbon compounds they absorb for respiration + to make more complex compounds in their cells.
- When large material are dead, they are changed to peat/ coal by heat + pressure on Earth. oil + natural gas is formed by dead microscopic sea plants + animals.
- peat/ coal/oil + natural gas - fossil fuels , contain carbon compounds , burning this releases carbon back to atmos as carbon dioxide.
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Bacteria + nitrates - Soil fertility is maintained by decomposers. Theses organisms release carbon + nitrogen compounds when they break down dead material.+ their waste. Farmers use decay process to add manure.
- Soil bacteria convert nitrogen gas to nitrogen compounds in soil.(nitrogen fixing bacteria).
Peas + beans have mutalistic relationship.Plants get compounds directly from bacteria + bacteria protected inside nodules in plant roots.Crop rotation- benefit from the additional nitrogen compounds in soil.
Nitrogen in plants - Plants contain nitrogen compounds in proteins + DNA. Plants need nitrogen to make more of these compounds. Cannot use unreactive nitrogen from air. Instead absorb nitrogen compounds :nitrates that dissolve in soil water.