Earth and Space Sciences
Global Systems
Define: lithosphere, atmosphere, hydrosphere, biosphere.
o Lithosphere: earth’s crust – mountains, continents, ocean floor
o Atmosphere: layer of gases around the earth
o Hydrosphere: all the water on earth – oceans, seas, rivers, lakes, ice caps
o Biosphere: all living things – plants, animals, bacteria, man
Label and explain diagrams for the carbon, nitrogen, phosphorus and water cycles.
o Label the diagrams, explain how materials move through the cycles
Explain the importance of these natural cycles in creation.
o No new materials are created so nutrients have to be recycled when plants & animals die and decompose to be available for new organisms, otherwise nature will run out of materials
o C is needed for the structure of all organisms and for the fuel molecules all living things need (glucose)
o N is essential for DNA and for proteins – structural materials of living things
o P is necessary for cell membranes, energy molecules, bones
Describe how photosynthesis and respiration relate to the carbon cycle.
o Plants bring C into living things from the atmosphere through photosynthesis and produce glucose. Respiration is when CO2 is produced in the cells of all living things and returned to the atmosphere through breathing out.
Explain the role and importance of different bacteria in the nitrogen cycle.
o Nitrogen fixing bacteria convert N2 from the atmosphere into ammonium and nitrates in the soil – now N is available to plants in a water-soluble form
o Denitrifying bacteria convert nitrates and ammonium back into N2 and return it to the atmosphere.
Discuss the impact of human activity on the nutrient cycles (C, N & P).
o Burning fossil fuels, land clearing, deforestation affect the C cycle.
o Excessive use of fertilizers impacts the N and P cycles
Explain how greenhouse gases affect the temperature of the Earth (greenhouse effect).
o These gases absorb and trap some of the infra-red radiation that is emitted from the earth and so keep the atmosphere temperature constant and mild
o Water vapour, CO2, methane, nitrous oxide, ozone
Identify the major factors that influence the world’s climate.
o Surface of the earth, tilt of the earth (causes seasons), gases in the atmosphere, oceans and ocean currents
List the main causes of ocean currents.
o Wind, temperature of the water, variation in salt levels, rotation of the earth on its axis, gravitational pull of the sun and moon
Explain the difference between surface and deep currents and the role they play in the global conveyor belt.
o Surface currents form by winds on the top
o Deep currents are caused by differences in temperature and salt levels. Cold saltier water sinks down, warmer less dense water rises – thermohaline circulation.
o Cold water moves deep down from poles to equator, warmer upper layer water moves from equator to poles – global conveyor belt distributes heat around the earth
Describe the relation between the Southern Oscillation Index (SOI) and El Niño and La Niña events.
o In the Pacific Ocean, differences in water temperatures near South America and Australia influence the weather in east Australia.
o El Niño – water temperatures near Australia are cooler – less rainfall, drier conditions, can lead to droughts, warmer summers, heat waves and bushfires
o La Niña – water temperatures near Australia are warmer – more rainfall and possible more storms and cyclones – can lead to floods
Explain influence of the Indian Ocean Dipole (IOD) on the weather in the southern parts of Australia.
o Differences in water temperatures in the Indian Ocean near Africa and Australia
o If cooler water near Australia – less evaporation and rainfall – drier conditions
o If warmer water near Australia – more evaporation and rainfall over central and southern Australia
Describe a variety of evidence that indicate that the Earth is gradually warming.
o Glaciers and ice caps have become smaller in size
Evaluate whether human activities are influencing the change in climate.
o Are human activities the only possible cause for the warming of the climate?
o There could be natural events that cause the warming of the atmosphere which would then increase CO2 levels by releasing it out of the sea
Describe how CO2, methane and nitrous oxide levels in the atmosphere have changed in recent times.
o The levels of these gases in the atmosphere have all increased over the past 50-200 years due to increased industry and burning of fossil fuels, agricultural activities, cattle farming, rice growing, melting of the permafrost
o Increasing the amount of these gases in the atmosphere traps more heat – this is called the ‘enhanced greenhouse effect’ – extra due to human activity
Explain the importance of the ozone layer for life on Earth and the effect of changes in the ozone layer.
o Ozone filters out most of the harmful radiation from the sun (x-rays, most uv) and so protects living things from being damaged by this radiation
Explain the effect of climate change on biodiversity.
o As the climate warms this can change the habitat for organisms, causing them to move to different areas or be less able to survive and so become endangered or extinct
Space Science
Explain how constellations move across the sky during the night and during the year.
o During the night they move (E to W) because the earth rotates (spins) from west to east
o During the year different constellations can be seen because the earth orbits (moves around) the sun
o During the night stars rotate around the South Celestial Pole (SCP)
Define: constellation, ecliptic.
o Constellation: a group of stars in a pattern making an imagined shape.
o Ecliptic: the path that the sun, moon and planets follow as they move across the sky.
How do we express distances in space (astronomical unit, light year, parsec)?
o 1 astronomical unit (au) is the distance from sun to earth (150 million km)
o 1 light year (ly) is the distance light travels in 1 year (9.5 million million km)
o 1 parsec (pc): equal to 3.26 ly, related to angle measure using parallax
How do we order stars in a constellation?
o Stars in a constellation are ordered by their brightness from earth using Greek letters – alpha, beta, gamma, delta, epsilon, …
What are stars composed off?
o Stars are composed of hydrogen gas (75%) and helium gas (25%)
What generates the energy in stars?
o The energy and light (radiation) come from a nuclear fusion reaction in the core of the star – 2 H atoms combine to form 1 He atom and release lots of energy. This energy radiates out into space after it reaches the surface of the star.
How does star colour relate to temperature; what is the meant with different spectral classes?
o Red stars are the coolest (3000°C), blue stars are the hottest (35000°C)
o Stars also vary greatly in size from dwarf stars smaller than the size of earth to red and blue supergiants, thousands of times greater than the size of earth, and far greater than the size of the sun
o The H-R diagram shows the relationship between size and temperature of stars and indicate different groups of stars (white dwarf, main sequence, (super)giants)
o Stars are also classified according to an analysis of the spectrum of colour emitted by the star (OBAFGKM)
What is the difference between apparent & absolute magnitude?
o Apparent magnitude: how bright the stars appear from earth
o Absolute magnitude: how bright the stars are compared to each other, if they were all the same distance from earth (10 parsec)
o Brightness is indicated with a number: the more negative is brighter, the more positive (the bigger the number) is dimmer
Describe / define binary star, galaxy, nebula, globular cluster, supernova.
o Binary star: 2 stars that orbit each other
o Galaxy: large collection of billions of stars in space, measuring many light years across, like the Milky Way galaxy that our sun is part of
o Nebula: a cloud of gas and dust in outer space often visible as an indistinct and hazy area
o Globular cluster: a large number of stars grouped close together
o Supernova: an exploding star that can be seen as a sudden bright appearance
What is the supposed origin of the universe according to the big bang theory?
o All the energy in the universe existed in a single point (singularity) and suddenly exploded 13.7 billion years ago; very rapid expansion followed by cooling of matter to form the universe we know today – formation of atoms, then particles, stars and planets. The Earth is said to have been formed about 4.5 billion years ago.
o There are many scientific problems with this theory
Identify the ‘evidence’ given supporting the big bang theory:
o Edwin Hubble’s observations (expanding universe) – galaxies are red-shifted: their colour moves towards a longer wavelength – this indicates they are moving away from us (Doppler effect)
o Detection of cosmic microwave background radiation – this is said to be the afterglow of the temperature at the big bang