briefly describe the non-cyclical nature of energy flow
- The sun is the ultimate source of energy.
- Explain photosynthesis
- Energy in the producers is passed from one trophic level to another by feeding.
- Flow of energy through the ecosystem is non-cyclic. Energy is lost as heat to the environment through respiration. Since this heat energy does not return back into the same system, it cannot be recycled.
- Egested & excreted materials, & dead organisms conain trapped chemical energy. Decomposers break down any decaying organic matter. The respiration of decomposers releases heat and carbon dioxide into the atmosphere.
producer
- trap light energy from the sun and convert it into chemical energy
- synthesise glucose from carbon dioxide and water to form glucose and oxygen via photosynthesis
- affect the lives of other organisms because they provide them with oxygen and energy
consumer
- organisms that are unable to make their own food
- obtain energy and nutrients by feeding on other organisms
trophic level
Feeding position of an organism in a food chain
describe how carbon is cycled within an ecosystem
- Photosynthesis
- Feeding
- Combustion
- Respiration
- Decomposition
role of forests as carbon sinks
- Carbon dioxide is taken in by the trees and used in photosythesis.
- Due to photosynthesis, carbon compounds are formed which are then stored within the trees.
- When trees die, their remains may be buried deep in the ground to form coal which traps carbon
role of oceans as carbon sinks
- Dissolved carbon dioxide is used by phytoplanktons, algae and water plants
- The carbon is then stored as carbon based molecules in them.
- This carbon is also stored as carbon based molecules in the organisms that eat PAW
- When these organisms die and are buried in the seabed, they form fossil fuel to keep the carbon trapped.
effects of water pollution by sewage & inorganic waste
May contain disease-causing organisms such as bacteria
- Affect large no of ppl (if it gets into drinking water)
- Water-bourne diseases eg: cholera & typhoid
Contains phosphates & nitrates(nutrients for algae & water plants):
- Eutrophication: The process where water recipes excess nutrients (phosphates & nitrates), which causes excessive growth of algae & water plants
- Overgrowth of algae & floating water plants - prevent sunlight
- Submerged algae & water plants die (lack of sunlight) - decomposed by aerobic bacteria & fungi
- Bacteria feeding on decaying organic matter grow & multiply rapidly - use up oxygen in water
- Fishes die (lack of oxygen)
effect of pollution due to insecticides
- due to bioaccumulation, insecticides accumulate inside the body of animals & plants as they may not be excreted, thus stored in fatty tissues of organisms that consume it
- due to amplification, amount of insecticide increase as animal in higher trophic level feed on anmals & plant of lower trophic level
- predators in higher trophic level would take in the greatest amount of insecticides, with bioaccumulation & bioamplification, large amount of insecticide is present in the body
sewage treatment
- Used water is first passed through bar screens to remove large, course materials (grit,rags)
- Primary treatment: liquid flows through the tank very slowly - allows the solid suspensions to settle to the bottom of the tank as primary sludge
This sludge is removed and fed into an aerobic digester. - The top liquid from this tank flows into an aeration tank.
- In the aeration tank, the liquid is mixed with aerobic microorganisms, mainly bacteria. Bubbles of compressed air - pumped into the liquid through pipes in the floor of the tank. Dissolved oxygen is used by the microorganisms for aerobic respiration
- The microorganisms breakdown the organic pollutants in the water. The treated water, together with the microorganisms, is channelled into the final settlement tank.
- Here, the microorganisms settle to the bottom of the tank as sludge. A portion of this sludge is returned to the aeration tank for reuse, excess sludge is sent to the anaerobic digester.
- The clean water at the top of the tank may be discharged as effluent into nearby rivers, streams and lakes
- In anaerobic digester (closed tank, no oxygen), anaerobic bacteria decompose the sludge, break down the organic matter, producing biogas, mainly methane (Fuel: generate electricity for the functioning of the reclamation plant)
- The remaining solid material is removed from the tank - fertiliser or burnt in an incinerator
reasons for conservation
- Marine life are a major source of human food
- Rainforests are a source of raw materials for industries
- Prevents extinction of animal and plant species
- Maintenance of a large gene pool
- Maintenance of a balanced ecosystem
- Studies on wildlife provides useful information for humans
- Preservation of natural scenery and wildlife
how conservation is done
Management of fisheries:
- regulating entry of ships into fishing grounds
- banning the harvesting or fishing of endangered species
- limiting the period of fishing in fishing grounds
- raising endangered species of fish in hatcheries and releasing them into fishing grounds where fish population are decreasing
Management of timber production:
- various gov laws ensure that trees felled for timber are cut down selectively & at regulated rate
- young trees not felled
- new seedlings planted to replace trees that were cut down for timber; reforestation (planting trees to replace trees cut down)
