Habitat

The physical environment that an organism (or a population of organisms) lives in is called it's Habitat. It can be described using the biotic and abiotic factors we have been looking at. For each of the biotic features an organism will have a prefered niche range. Outside this range the some organism will may survive in a marginal niche, but will be stressed. Large variance from the prefered niche normally causes the organisms to avoid those conditions (if mobile) and may cause death.




The above graph show plant growth at a range of temperature. In class we looked at a W.A. study on trout which found their prefered niche was 8 - 17 oC. The study also showed trout could survive in water as cold as 2oC and as hot as 27oC, but outside the prefered range they were unlikely to breed. The study also looked at other factors such as pH, and salinity.


We also looked at Dingo habitats and saw that a very mobile animal such as a Dingo may have everal types of habitat in a pack's home range such as Hills, Woodland and Riverine in order to provide all the water and prey the pack needed. The dingos seemed to prefer the productive wooded riverbanks and spent a large proportion of their time in these areas only occasionally visiting the rocky mountainous areas in their range.

Earth’s components

The Hydrosphere – includes all the water found on Earth (Lakes, ponds, oceans ice caps and even water vapour in the air. All organisms depend on water for their metabolism; most chemical reactions take place in water. (Remember Hydro means water in Greek.)

The Atmosphere – the envelope of air that surrounds the Earth. It is often subdivided into four zones (called from lowest altitude to highest: the troposphere, stratosphere, mesosphere and thermosphere) (Remember atmos means air or vapour in Greek.)


The Lithosphere – the outermost solid layer of Earth, its crust and upper mantle. It is made of the large mobile plates we studied in geology both land masses and under the ocean floor. In this topic we will be most interested in the rock and soil types. (Remember litho means rock in Greek.)


These entire three systems link together to form a Biosphere, a region that supports living things (or biota.) It is common to subdivide the Biosphere into regions characterised by their main plant types.

These regions called Biomes include deserts, tundra, tropical rainforest, savannah, and alpine areas.

The Ecosystem describes the way organisms are found together in a physical place. Both physical (abiotic) and biological (biotic) factors describe an ecosystem. Examples of abiotic factors may be: wind speed, humidity, rainfall, soil type, air temperature etc. While biotic factors may include the presence of producers, parasites, competitors, pathogens and decomposers in the community

Radio Signals

When you tune in your radio you are listerning to information sent by a broadcaster as a carrier wave. There are however two ways to modulate this underlying carrier wave signal. On your radio there will be an AM/FM switch to swap between radio stations that use these two methods.

FM radio works the same way that AM radio works. The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM, the frequency (the number of times each second that the current changes direction) of the carrier signal is varied.

FM signals have a great advantage over AM signals. Both signals are susceptible to slight changes in amplitude. With an AM broadcast, these changes result in static. With an FM broadcast, slight changes in amplitude don't matter -- since the audio signal is conveyed through changes in frequency, the FM receiver can just ignore changes in amplitude. The result: no static at all.

Digital radio only needs to carry on/off digital information, like a computer or a cd, so digital radio uses the AM system.

Radio waves like all other forms of electromagnetic radiation travel at the speed of light (300 000 000m/s).

Our wave equation says that:

velocity (metres per second) = frequency (hertz Hz) x wavelength (metres)

which can be written i short as: v= f ƛ

Radio stations normally give their frequencies in KiloHertz. For example ABC Melbourne is on 774 KHz so has a wavelength of 300 000 000 / 774 000 = 388m