Name:
Class:
School:
I give my permission for my answers to be placed on the TKI and NZQA websites as examples
of student work, knowing that my name will not be used with the answer.
Signed:
SAMPLE PAPER
3
Level 3 Earth and Space Science
3.4: Demonstrate understanding of processes in the
ocean 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 room for any answer, use the space provided at the back of this booklet.
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 ACHIEVED
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.
GSM can be seen in the level 1 and level 2
OVERALL
LEVEL
OF PERFORMANCE
exemplars from the 2012 examinations, which will be published on the NZQA website
when the assessment schedules are published.
© 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: THERMOHALINE CIRCULATION
Thermohaline circulation is the large-scale movement of water due to temperature and
salinity gradients.
http://www.shorstmeyer.com/msj/geo130/conveyor/conveyor.html
Discuss the transport of heat and water in the thermohaline circulation.
Your answer should include:
• how temperature affects the density of water
• how salinity affects the density of water
• effects of temperature and salinity differences on the circulation of water around the oceans.
Thermohaline circulation is global movement of water due to differences in temperature and
salinity. Both temperature and salinity affect the density of water.
Warmer water is less dense than cold water and will rise as a result in the tropical oceans. As
the water moves to the polar regions it will sink because it is colder, which makes it denser.
Earth and Space Science 3.4
Assessor’s
use only
3
The effect of salinity on the oceans is that the higher the salinity the denser the water,
therefore the dense salty water will sink. In the Antarctic area the water becomes very
salty so sinks as it moves to the tropical ocean where it becomes less salty and will rise.
Earth and Space Science 3.4
Assessor’s
use only
4
QUESTION TWO: CARBON CYCLE
The carbon cycle involves the atmosphere and the oceans. The oceans contain 50 times
more CO2 than the atmosphere.
Discuss how physical (solubility) and biological pumps work to cycle the CO2 in the oceans:
• explanation of physical and biological pumps
• how physical and biological pumps contribute to the movement of carbon in the oceans.
You may draw a labelled diagram in the box provided to support your answer.
Biological pumps are based on living things in the carbon cycle. All the living organisms in the
ocean contain carbon in their tissues/shells. When they die they sink to the ocean floor,
where the carbon is locked up for an extended time.
Earth and Space Science 3.4
Assessor’s
use only
5
The physical pump relies on the solubility of CO 2 in different temperatures of water. At the
poles the water temperature is lower, so more CO2 from the atmosphere is dissolved in the
surface water. At the equator, because the water is warmer, it can’t hold as much CO2.
Earth and Space Science 3.4
Assessor’s
use only
6
QUESTION THREE: LAYERING IN THE OCEAN
The oceans have three major layers. They are the mixed layer, the pycnocline (barrier
layer) and the deep layer.
http://oceanmotion.org/html/background/ocean-vertical-structure.htm
Discuss the key processes affecting each layer and how they interact with each other.
Your answer should include:
• the properties of each layer
• the transport of energy and matter
• the interaction of the three layers.
You may draw a labelled diagram in the box provided to support your answer.
Earth and Space Science 3.4
Assessor’s
use only
7
The mixed layer at the surface is where wind-driven surface currents occur. This layer is not
very deep, generally not greater than 100 m. The wind stirs the surface waters, resulting in a
well-mixed layer of uniform density.
The pycnocline is the middle layer between the mixed and deep layers. It typically extends
from 500 m to 1 000 m and is very stable. Water density changes rapidly through the
pycnocline with depth. This density change is a result of temperature and/or salinity.
The deep layer is below the pycnocline and is cold, dark and stable. Most of the ocean is deep
layer. In this layer density increases gradually with depth, and water only moves slowly in this
layer. There are not many currents in this layer.
Earth and Space Science 3.4
Assessor’s
use only
8
Extra space if required.
Clearly number the question (if applicable).
Question
number
Earth and Space Science 3.4
Assessor’s
use only
9
Extra space if required.
Clearly number the question (if applicable).
Question
number
Earth and Space Science 3.4
Assessor’s
use only