Hazards and ecosystems

1. What is the contour interval in metres? (1 mark)

20

Adjacent labelled contours differ by 20 m. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. Which statement about P is supported? (1 mark)

Between 120 and 140 m

A position between contours gives a height interval, not an exact height. For this 1-mark task, credit the keyed option.

1. Which description best fits the pattern? (1 mark)

Negative association

Tree counts generally fall as distance increases. For this 1-mark task, credit the keyed option.

2. Which conclusion is justified? (1 mark)

The observations show an association, but do not establish its cause.

An observational association alone cannot establish causation or universal applicability. For this 1-mark task, credit the keyed option.

1. What is the mean annual retreat rate in m/year? (1 mark)

5

95 m ÷ 19 years. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. Does this average show that retreat happened evenly each year? (1 mark)

No; the endpoint surveys do not show the annual pattern.

Storm events may concentrate change in a few years. Two endpoints establish net change, not its timing. For this 1-mark task, credit the keyed option.

1. What is the mean annual retreat rate in m/year? (1 mark)

5

60 m ÷ 12 years. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. Does this average show that retreat happened evenly each year? (1 mark)

No; the endpoint surveys do not show the annual pattern.

Storm events may concentrate change in a few years. Two endpoints establish net change, not its timing. For this 1-mark task, credit the keyed option.

1. What is peak discharge in m³/s? (1 mark)

27

Read the maximum on the discharge line and its left axis. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. What is the peak lag time in hours? (1 mark)

4

Maximum rainfall is at hour 2; maximum discharge is at hour 6. Subtract 2. For this 1-mark task, credit the accepted numerical answer in the requested units.

3. What can this record establish? (1 mark)

The discharge peak follows the rainfall peak in this storm.

Travel time and storage can delay discharge, but one record does not identify a unique mechanism or prove a universal lag. For this 1-mark task, credit the keyed option.

1. What is P’s latitude in degrees? (1 mark)

-20

Use the horizontal latitude line through P; preserve its sign. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. What is P’s longitude in degrees? (1 mark)

-10

Use the vertical longitude line through P; preserve its sign. For this 1-mark task, credit the accepted numerical answer in the requested units.

3. Where does P lie? (1 mark)

Southern hemisphere

A latitude of zero is the equator. A positive latitude is north; a negative latitude is south. For this 1-mark task, credit the keyed option.

1. Which description best fits the pattern? (1 mark)

Curved association

Tree counts fall and then rise. A curved relationship can exist even when a straight-line correlation is zero. For this 1-mark task, credit the keyed option.

2. Which conclusion is justified? (1 mark)

The observations show an association, but do not establish its cause.

An observational association alone cannot establish causation or universal applicability. For this 1-mark task, credit the keyed option.

1. Which description best fits the pattern? (1 mark)

Curved association

Tree counts fall and then rise. A curved relationship can exist even when a straight-line correlation is zero. For this 1-mark task, credit the keyed option.

2. Which conclusion is justified? (1 mark)

The observations show an association, but do not establish its cause.

An observational association alone cannot establish causation or universal applicability. For this 1-mark task, credit the keyed option.

1. Which description best fits the pattern? (1 mark)

Positive association

Tree counts generally rise as distance increases. For this 1-mark task, credit the keyed option.

2. Which conclusion is justified? (1 mark)

The observations show an association, but do not establish its cause.

An observational association alone cannot establish causation or universal applicability. For this 1-mark task, credit the keyed option.

1. What is the total annual rainfall in mm? (1 mark)

948

Add the rainfall for all twelve months. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. What is the annual temperature range in °C? (1 mark)

16

Subtract the lowest monthly temperature from the highest. For this 1-mark task, credit the accepted numerical answer in the requested units.

3. In which month is the highest mean temperature? (1 mark)

Jul

Identify the highest point on the temperature line. For this 1-mark task, credit the keyed option.

1. Calculate cross-sectional area in square metres. (1 mark)

1.2

Width × mean depth = 4 × 0.3 = 1.2 m². For this 1-mark task, credit the accepted numerical answer in the requested units.

2. Calculate discharge in cubic metres per second. (1 mark)

0.6

Discharge = cross-sectional area × mean velocity = 1.2 × 0.5 = 0.6 m³/s. For this 1-mark task, credit the accepted numerical answer in the requested units.

3. Explain a limitation of estimating the section as a rectangle. (2 marks)

Depth varies across the channel. Several depth measurements and a more realistic cross-section could improve the area estimate. A surface float also may not represent mean velocity through the water column.

Depth varies across the channel. Several depth measurements and a more realistic cross-section could improve the area estimate. A surface float also may not represent mean velocity through the water column. Original credit guidance: credit relevant explained reasoning; accept accurate alternatives.

1. Which design directly represents each zone? (1 mark)

Use random locations within each zone

Stratified sampling includes each zone; random locations within zones reduce convenience and selection bias. For this 1-mark task, credit the keyed option.

2. For proportional allocation of 40 samples, how many go in the middle zone? (1 mark)

20

The middle zone is 50/100 of the total length: 0.5 × 40 = 20. For this 1-mark task, credit the accepted numerical answer in the requested units.

3. How could the team make pebble size measurements comparable? (2 marks)

Use the same axis, units and instrument throughout; record the rule for selecting the pebble at each location. Measure rather than classify by eye.

Use the same axis, units and instrument throughout; record the rule for selecting the pebble at each location. Measure rather than classify by eye. Original credit guidance: credit relevant explained reasoning; accept accurate alternatives.

1. Which class contains district C? (1 mark)

20 to less than 30%

23 is at least 20 and below 30. For this 1-mark task, credit the keyed option.

2. How many households in A reported damage? (1 mark)

60

6% of 1,000 = 60. For this 1-mark task, credit the accepted numerical answer in the requested units.

3. Does the darkest district necessarily have the most affected households? (1 mark)

No; the household denominators differ.

A high rate in a small population can represent fewer households than a lower rate in a large population. For this 1-mark task, credit the keyed option.

1. What is the ground distance in kilometres? (1 mark)

9

9 × 100000 cm ÷ 100,000 = 9 km. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. How many centimetres would 2 km occupy on this printed map? (1 mark)

2

2 km is 200,000 cm. Divide by 100000. For this 1-mark task, credit the accepted numerical answer in the requested units.

1. What is the contour interval in metres? (1 mark)

10

Adjacent labelled contours differ by 10 m. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. Which statement about P is supported? (1 mark)

Between 50 and 60 m

A position between contours gives a height interval, not an exact height. For this 1-mark task, credit the keyed option.

1. What is the contour interval in metres? (1 mark)

20

Adjacent labelled contours differ by 20 m. For this 1-mark task, credit the accepted numerical answer in the requested units.

2. Which statement about P is supported? (1 mark)

Between 100 and 120 m

A position between contours gives a height interval, not an exact height. For this 1-mark task, credit the keyed option.