What is ecology?
The study of inter-relationships in and between living and non-living factors in an ecosystem.
Define:
ecosystem
A unit containing all of the organisms and their environment, interacting together in a given area i.e. decomposing log or lake (habitat)
Define:
Biotic Factor
Provide three examples
Living factor in the environment i.e. heterotrophs, autotrophs, saptotrophs.
Define:
Abiotic Factor
Provide Three Examples
Non-living factor in the environment i.e. water, air, light, soil, climate.
How much energy is lost from one trophic level to another?
90% of the energy is lost.
List some of the reasons for energy loss in consumers.
- Faeces and urine
- Respiration
- Movement and other activities
- To maintain temperature
- Heat loss to environment
- Not all parts of the organism are eaten.
List some of the reasons for energy loss in producers.
- Not all wavelengths are trapped.
- Some light reflected.
- Light passes through leaves and not trapped.
- Light does not fall on leaves.
What are the causes of imbalances in the food chain?
Organisms can:
- Dies of disease
- Pollution
- Use of pesticides
- Lack of resources i.e. food
- Emigration
- Over predation and hunting.
What are the four types of pyramids?
- Names
- Numbers (Note: different structures)
- Biomass
- Energy
Why are shorter chains more efficient?
- Shorter chains are more efficient since energy is lost, fewer prganisms will lose less energy which means more energy available for consuers higher up.
- Some farmers keep animals in enclosures to prevent energy loss.
Define:
population
A population is a group of organisms of one species living in the same area.
What are the some factors that affect a population.
- When a population increases by birth-called birth rate/fertility rate
- A population can increase by immigration (ncoming)
- A popluation decreases by death/mortality rate or by emigartion (going out) migration.
Define:
limiting factor
And list some of the limiting factors.
Any factor that limits the growth of a population.
Examples include:
- Food supply and other resources
- Predator/prey relationship
- Disease
- Natural disaster
List and describe the different phases in a sigmoid graph.
- Lag phase: Initially the population grows slowly since it takes time for organisms to settle and mature before breeding.
- Geometric/Exponential phase: The population increases in a compound interest manner since no limiting factor however this eventually stops as competition sets in, overcrowding, mature individuals die, food and other reasources become limiting factors.
- Stationary phase: Population becomes stabe almost as if death rate=brith rate.
- Death phase: If population continues to decline then the death phase is present, can be caused by: insufficent food and othe resources, waste contamination, disease and natural factors i.e. floods, drought, etc.
List the factors that increase human population.
- Decrease in infant mortality
- Increase in life expectancy.
But this still does not affect why?
Factors that changed the mortality rate:
Agricultural devolopment, economic expansion, medical revolution, industrial revolution.
List and describe the different phases in a geometric graph.
- Lag phase: Initially, the humans face a steady increase in the population, settling into environments as well as other factors i.e. lack of medicine, hygiene, etc.
- Exponential phase: After the industrial, agricultural and medical revolution lead to greater developments in peoples lives. More people started having jobs and an income, farming became more efficient and greater discoveries in medicine lead to a huge spike in the population that now just seems never ending.
Describe the water cycle.
