SAMPLE PAPER
2
Level 2 Earth and Space Science
2.7: Demonstrate understanding of physical principles
related to the Earth System
Credits: Four
Check that you have completed ALL parts of the box at the top of this page.
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.
This exemplar has been generated by a subject expert not a candidate.
© New Zealand Qualifications Authority, 2011
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: WHY IS THE SKY BLUE?
Sunlight is considered to be white light and contains all the colours of the spectrum.
(Simplified representation of visible light spectrum.)
Explain why the sky is blue when viewed from the Earth. In your answer, you should consider:
• how light travels through space to reach Earth
• how colours of white light (in particular red and blue) differ from each other
• how the different colours of light (in particular red and blue) are transmitted, absorbed and
scattered in the Earth’s atmosphere.
You may draw a labelled diagram(s) in the box provided to support your answer.
The sun makes light energy. It travels through space to Earth by heat transfer called
radiation. This is because space is a vacuum with no particles and means lights can
travel in a straight line.
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White light is made up of 7 colours (ROYGBIV). Each colour has a different wave length and
frequency but they still travel at the same speed.
Red light has the biggest wave length and therefore has the smallest frequency.
The blue light has a much smaller wave lengths and therefore a much higher frequency.
When white light reaches Earth’s atmosphere different things happen to the difference
colours/wavelengths.
The Earth’s atmosphere is made up of lost of little particles, eg, gas molecules and wee bits
of dust. When light hits a particle in the atmosphere it can be transmitted (pass through it)
or it can be absorbed. If the light is absorbed it will get reflected back out at a different
angle (scattered), and bent. When high frequency blue wave lengths hit a particle they
often get absorbed and scattered back down to Earth. This makes the sky look blue.
This answer is at a Merit level because it:
• explains how light is energy and travels in straight lines
by radiation through a vacuum (space)
• describes properties of colours of lights (red and blue)
• explains interactions of blue light with particles in the
atmosphere.
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QUESTION TWO: THE EARTH’S HEAT
The Earth’s core provides an internal heat source for the Earth.
Discuss the origin and distribution of this heat through the Earth, and the effects this may have on
the Earth system. In your answer, you should:
• explain the origin of the internal heat source in the core of the Earth
• explain, with reasons, the method(s) of heat transfer in the core and the mantle of the Earth
• explain in detail how heat transfer impacts upon the Earth’s system. You may relate your answer
to the overall Earth system or any part of the Earth system.
You may draw a labelled diagram(s) in the box provided to support your answer.
The Earth’s core is very hot. This is due to several reasons. One residual heat from when
Earth was formed is present but more importantly heat is generated by radioactive
decay. Big atoms break down by nuclear fission to become stable, and when they do this
they make large amounts of heat energy.
Heat moves out of the core by conduction. This is where particles have to touch so the heat
energy can be passed along, eg, in the solid inner core.
In the outer core heat is transferred to the mantle by convection. This is because the outer
core and the mantle are liquid. The particles in the outer core heat up, become less dense
and rise, as they lose heat energy to the lower mantle the particles sink back down. This
forms a convection current.
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Another convection current will develop in the upper mantle and heat will be transferred to
the surface of the Earth.
This answer is at a Merit level because it explains:
• that the heat source in the core is radioactive decay
and that fission reactions are the source of this heat
energy
• convection occurring in the mantle and how these
currents transport heat to the surface of the Earth.
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QUESTION THREE: OCEAN’S TEMPERATURE
Explain why the oceans at the equator are always warm. In your answer, you should:
• explain the source of the Sun’s heat energy
• explain in detail how heat energy travels from the Sun to the surface of the Earth (ocean)
• explain the difference in temperature of ocean water at the equator compared to ocean water at
the poles.
The sun’s heat energy is made by nuclear fusion. Hydrogen atoms are converted into
helium atoms and this produces large amounts of heat (infra-red) energy.
This infrared radiation is part of the electromagnetic spectrum and therefore reaches
Earth’s atmosphere by radiation. It can easily travel through space as it does not need
particles to travel through once infra-red radiation reaches the atmosphere it gets moved by
convection currents. To heat up the ocean’s water, conductions occurs between the
particles in the air and the particles of the water. But why is the equator warmer than the
poles.
The Earth is tilted and so the sun shines on it basically equally. However, year round the
ocean at the equator gets the same amount of heat energy from the sun which makes the
ocean at the equator warmer.
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This answer is at a Merit level because it:
• explains fusion in the Sun being the source of the heat energy
• explains radiation through space and convection through atmosphere as
methods of heat transfer
• explains how water at the equator receives constant heat energy from the
Sun so remains warm – does not contrast this water at the poles.
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