Download Merit - NZQA

SAMPLE PAPER
2
Level 2 Earth and Space Science
2.6: Demonstrate understanding of stars and
planetary systems
Credits: Four
You should answer ALL parts of ALL questions in this booklet.
If you need more space for any answer, use the page(s) provided at the back of this booklet and
clearly number the question.
Check that this booklet has pages 2–9 in the correct order and that none of these pages is blank.
YOU MUST HAND THIS BOOKLET TO YOUR TEACHER AT THE END OF THE ALLOTTED TIME.
EXEMPLAR FOR MERIT
NOTE: These exemplars do not fully show Grade Score Marking (GSM) because of
the small sample of student scripts involved, and the absence of a cut score meeting
to determine grade boundaries. In 2012, level 1 2011 examination papers will have
exemplars marked full in accordance with GSM. These will be published on the
NZQA website when the assessment schedules are published.
OVERALL LEVEL OF PERFORMANCE
This exemplar has been generated by a subject expert not a candidate.
© New Zealand Qualifications Authority, 2012
All rights reserved. No part of this publication may be reproduced by any means without the prior permission of the New Zealand Qualifications Authority.
2
You are advised to spend 60 minutes answering the questions in this booklet.
QUESTION ONE: THE SUN
The Sun is at the centre of our solar system and provides the energy source for life on
Earth.
Explain in detail EACH of the stages (birth, life, and death) in the life cycle of the Sun. In your
explanation, you should make reference to the energy changes:
•
fuel use
•
mass
•
gravity.
You may draw a labelled diagram (s) in the box provided to support your answer.
The sun was born in a giant molecular cloud (GMC). The GMC began to collapse inwards
due to gravity and it formed a proto-star. This was the beginning of the stars life. It then
began to fuse hydrogen into helium releasing vast amounts of energy e.g. sun light. Over
time the mass of the star decreases as it uses up its hydrogen. Eventually the star runs out
of hydrogen. To cope with this it turns into a red giant and expands outwards. When the
star runs out of helium, gravity will cause the core to collapse and the sun will turn in to a
dense white dwarf with no fuel to burn.
The candidate explains the three difference stages –
birth, life, and death, but does not link between them.
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QUESTION TWO: OUR SOLAR SYSTEM
Explain in detail how our solar system came to have inner and outer planets. In your answer, you
should consider the:
• formation of the solar system (including planets and their associated moons)
• size and composition of the inner and outer planets
• other features of the inner and outer planets related to their formation and ongoing existence.
Our sun formed in a giant molecular cloud (GMC) in the Milky Way galaxy. It was at the
centre of this cloud where gravity was at its greatest that the sun was born. It formed as the
cloud contracted and nuclear reactions began.
Surrounding our sun was a huge cloud of gas and dust, this cloud was spinning around the
sun. It caused matter to stick together and eventually gravity held it together and formed
planets orbiting around the huge sun in the centre. Moons and satellites formed around the
planets.
The inner planets are small and rocky (iron, nickel and silicates) and the outer planets are
huge balls of gas. This difference is because when the proto-star ignited, the solar winds it
produced blew away all the gas from the inner planets but the outer planets were not
affected because they were so far away.
The candidate has explained how the solar system formed
with the inner and outer planets. Some features are
described and why they occurred is explained, eg, the size
or number of moons or atmosphere.
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QUESTION THREE: USING THE HERTZSPRUNG-RUSSELL DIAGRAM
Red giants and white dwarfs are labelled on the Hertzsprung-Russell (HR) diagram below.
Explain in detail how the characteristics of red giants differ from those of white dwarfs. In your
explanation, you should consider:
•
the position of the red giants and white dwarfs on the Hertzsprung-Russell diagram
•
EACH of the following properties:
• temperature
• spectral class
• luminosity
• fuel source
• surface area
• mass.
Red giants are bright starts (10-100 x brighter than our sun) that have used up all of their
hydrogen fuel. To fuse He → C their core had to collapse and their outer layers expanded
outwards. This means red giants have a large surface area but a low temperature range of
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2, 500 – 5, 000 k. Their spectral types are G, K or M. White dwarfs are a type of star with a
high temperature range, 7, 500 – 30, 000 K. They are
not very bright as they are found on the bottom left of the H/ R diagram. Their luminosity is
between 10- 10,000 K x dimmer than our sun. White dwarfs have a spectral type of O, B, A,
F.
The candidate explains how a red giant forms and operates and
how a white dwarf forms and operates. One of the fuel sources is
correctly explained.
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