1. 1
   An astronomer compares the light spectra received from several distant galaxies with light produced by the same elements in a laboratory on Earth.

   (a)

   What change in wavelength is observed in light received from most distant galaxies?

   [1 mark]

   • AAn increase
   • BA decrease
   • CNo change
   • DA reversal

   (b)

   What term describes this observed increase in wavelength from distant galaxies?

   [1 mark]

   • ABlue-shift
   • BDoppler collapse
   • CRed-shift
   • DSpectral drift

   (c)

   Describe the relationship between a galaxy's distance from Earth and its observed red-shift.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A science journalist is writing an article to explain to the public why most scientists believe the universe began with the Big Bang.

   (a)

   According to the Big Bang theory, what were the conditions of the universe at its very beginning?

   [1 mark]

   • ACold and spread out
   • BExtremely hot and dense
   • CEmpty and dark
   • DCool and slowly expanding

   (b)

   Which observation provides evidence supporting the Big Bang theory?

   [1 mark]

   • AThe constant wavelength of starlight
   • BThe circular orbits of planets
   • CThe presence of moons around planets
   • DThe red-shift of distant galaxies

   (c)

   Explain what red-shift evidence tells us about the size of the universe over time.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Since 1998, a team of astrophysicists has been analysing brightness data from distant supernovae to determine how the rate of expansion of the universe is changing over time.

   (a)

   Explain what the 1998 supernova observations suggested about the expansion of the universe.

   [3 marks]

   (b)

   A galaxy further from Earth shows a greater red-shift than a closer galaxy. Explain what this tells us about the speed at which each galaxy is moving away from Earth, and what this implies about the universe overall.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   During a university open day, a physics professor tells prospective students that despite decades of research, there is still much about the universe that scientists do not fully understand.

   (a)

   Explain how observations of red-shift support the Big Bang theory of the origin of the universe.

   [6 marks]

   (b)

   Describe what is meant by dark matter and dark energy, and explain why their existence suggests there is much still not understood about the universe.

   [6 marks]

   Total for question 4: 12 marks

End of questions