AQA-style topic test · Space Physics · Higher tier
🔷 The whole of Space Physics is SEPARATE PHYSICS ONLY. Combined Science students do not need this test.
Time allowed: 35 minutes · Total: 28 marks
Instructions: Answer all questions on paper. Open the mark schemes only when you have finished the whole test.
Question 01
01.1 Describe the life cycle of a star that is much more massive than the Sun, from its formation to the end of its life. [6 marks]
Mark scheme
Level 3 (5–6 marks): a clear, logical description of all the main stages in the correct order, with the processes that cause each change.
Level 2 (3–4 marks): most stages in the correct order, with some explanation.
Level 1 (1–2 marks): some stages named, possibly in the wrong order.
0 marks: no relevant content.
Indicative content:
• a cloud of dust and gas (nebula) is pulled together by gravity
• it becomes a protostar; the temperature rises as it gets denser
• when hot enough, hydrogen nuclei fuse into helium – a main sequence star
• gravity is balanced by outward pressure from fusion, so it is stable
• when the hydrogen runs out, it swells into a red super giant
• heavier elements (up to iron) are made by fusion
• it explodes as a supernova, making elements heavier than iron and spreading them through the universe
• it leaves a neutron star or, if massive enough, a black hole
Question 01 total: 6 marks
Question 02
02.1 Explain why a main sequence star stays the same size for billions of years. [2 marks]
Mark scheme
the inward force of gravity (1)
is balanced by the outward pressure from the energy released by fusion (equilibrium) (1)
02.2 The Earth contains elements heavier than iron, such as gold. Explain how these elements came to be on Earth. [2 marks]
Mark scheme
they were made in a supernova (explosion of a massive star) (1)
the explosion spread them through space, and they became part of the cloud that formed the Solar System (1)
02.3 Which process produces the energy of a main sequence star? [1 mark]
Mark scheme
nuclear fusion (of hydrogen into helium) (1)
Question 02 total: 5 marks
Question 03
03.1 A satellite moves in a circular orbit at a constant speed. Explain why its velocity is changing and why it is accelerating. [3 marks]
Mark scheme
velocity is a vector, so it has a direction (1)
the direction of the satellite is always changing, so its velocity is changing (1)
a changing velocity means it is accelerating, caused by the gravitational force towards the centre of the orbit (1)
03.2 Explain why a satellite in a smaller orbit must travel faster than one in a larger orbit. [3 marks]
Mark scheme
closer to the Earth, the gravitational force is stronger (1)
so the satellite must move faster to stay in orbit / not fall towards the Earth (1)
for a stable orbit, if the speed changes the radius must change too (1)
Question 03 total: 6 marks
Question 04
04.1 Describe what scientists observe when they look at the light from distant galaxies. [2 marks]
Mark scheme
the light is red-shifted – its wavelength has increased (1)
the further away the galaxy, the bigger the red-shift (1)
04.2 Explain how red-shift provides evidence for the Big Bang theory. [3 marks]
Mark scheme
red-shift shows that galaxies are moving away from us (1)
more distant galaxies are moving away faster, so the universe is expanding (1)
if it is expanding, it must once have been very small, hot and dense – the Big Bang (1)
04.3 Since 1998, observations suggest that distant galaxies are moving away faster and faster. What have scientists suggested to explain this, and why is it uncertain? [2 marks]
Mark scheme
dark energy (1)
it has not been directly detected / scientists do not yet understand what it is (1)
Question 04 total: 7 marks
Question 05
A galaxy 200 million light years away is moving away from the Earth at 4400 km/s. Speed is directly proportional to distance.
05.1 Calculate the speed of a galaxy 500 million light years away. [2 marks]
Mark scheme
4400 × (500 ÷ 200) (1)
= 11 000 km/s (1)
05.2 Some scientists think the universe contains dark mass. Suggest why scientists cannot be certain about this. [2 marks]
Mark scheme
it cannot be seen / has not been detected directly (1)
it is only inferred from its gravitational effects / there is not enough evidence yet (1)
Question 05 total: 4 marks
END OF TEST. Total: 28 marks.
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