Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Ecology and ecosystems
Ecology – the study of living organisms in relation to their environment
Ecosystem – all the living organisms and the non-living factors in a particular part of the environment
Environmental survival kit
A supply of food – plants – CO2, water, light
A shelter – forested area for some animals
A breeding site – place needed for reproduction
Environmental factors – biotic-living organims- biocenosis
abiotic – water, land, temperature, humidity
...
03%), N2(78%)
Land – the source of inorganic substances, organic remains, habitat
Living together
A population – is all the members of the same species in a particular area
A community – is all the living organisms in one area
...

Food chain
Producers (plants﴿ → primary consumers (herbivores﴿ → secondary consumers (carnivores﴿ →
terciary consumers (aquatic habitats﴿ → top carnivore → → decomposers (fungi, bacteria﴿
Food web
-all different feeding relationships; The more complicated is a food web, the more stable the
community is
...

Environmental resistance (ER﴿– made up by all the factors affecting growth and size of population
The carrying capacity – the maximum number of a species that the habitat can hold, determined by
the availability of nutrients, shelter, breeding sites
Biotic potential – the ability to breed (bacteria – a high biotic potential, humans – a low biotic
potential﴿
Factors affecting population size II
...

Abiotic factors
Temperature - higher temperatures speed up enzyme-catalysed reactions → growth increase
Oxygen availability - affects the rate of energy production by respiration
Light availability - photosynthesis, breeding cycles in animals and plants
Toxins and pollutants - can affect the reproductive cycle (oestrogen-like substances﴿ or tissue
growth (SO2﴿
Humans exploit ER
-Predators eliminated from farms
-More available food for domestic animals
-Fertilisers and artificial light used for plant growth
-Predators used to control pests
-Anaerobic conditions, low temperatures – prevent microbes from consuming human food
-Pesticides eliminate competitors from crops
Relationship between organisms and their environment
Ecological valency (EV﴿ – the ability to tolerate different conditions of the environment
Minimum – pesimum - ecological optimum- pesimum – maximum (Gaussian curve﴿
Wide EV – cosmopolitan organisms
Narrow EV - bioindicators

Gaussian curve

Human population growth
Humans – alter their environment to raise the carrying capacity
Medical revolution – reduced the number of deaths
Industrial revolution – increased agricultural efficiency and improved housing conditions, the
number of births increased
Agricultural revolution – more efficient farming, more food available
Human success – world-wide distribution,large number of individuals, dominance over the species
Counting human population – directly - how many people of each group are present in a population
→ a population pyramid (age pyramid﴿ - important in planning use of resources
Population pyramids

Decay – natural process
Nutrients – reclaimed by the environment and returned to the ecosystems to be reused by other
organisms → scavengers (vultures﴿- dead bodies broken up into more managable pieces→
microorganisms– convert complex molecules in animals and plants into simpler compounds in the
soil and the atmosphere= nutrient cycles
Decomposing
Fungi + bacteria – saprotrophic feeding - secreting enzymes onto the remains → absorbing the
digested products
Decay process – provides energy and raw materials for the decomposers
Factors influencing decomposing
Heat – optimum temperature is needed for the activity of enzymes (generated by the respiration﴿
Oxygen – aerobic respiration – energy for driving the metabolism (anaerobic respiration – slow and
smelly – methan, hydrogen sulphid﴿
Water – hydrolysis reactions – splitting chemical bonds and dissolving the breakdown products
before absorption by the saprotrophs or other organisms
Importance of decomposition process to humans
Organic waste in sewage – providing drinking water
Removing of organic pollutants (spilled oil by decomposing bacteria﴿
Antiseptics and disifectants – hospitals, food preservation (inhibition the multiplication or
metabolism of saprotrophs﴿
Ecological succession
Ecological succesion(ES﴿ - is a series of changes to an ecosystem caused by complex interactions
between the community of living organisms and the abiotic environment
Primary succession – starts in an environment where living organisms have not previously existed
Secondary succession – occurs in areas where an ecosystem is present, but is replaced by other
ecosystems, because of a change in conditions
Biomes and biosphere
A biom – is a stable ecosystem that contains a group of organisms (the climax community﴿
The biosphere – is made up by all the biomes of the world together functions as one overall
ecological system, a thin layer of interdependent and interrelated biomes that cover the Earth



---