Secondary 1 Geography Semestral Assessment 2 (End of Year) Paper 3

TuitionGoWhere Practice Paper - Geography Secondary 1 SA2 Version 3 - Answer Key

Total Marks: 50

SECTION A: MAP SKILLS [15 marks]

Question 1

(a) 2962
Method: Read easting (vertical grid line) first: 29. Read northing (horizontal grid line) second: 62. The jetty symbol lies in the grid square bounded by eastings 29-30 and northings 62-63. Four-figure reference = 2962.
[1]

(b) 302612 (accept 302613 or 303612 depending on exact summit position)
Method: Six-figure reference divides each 1 km grid square into 10 tenths (100 m each). Puaka Hill summit is in grid square 3061. Estimate tenths: ~2/10 east of easting 30 → 302; ~1/10 north of northing 61 → 611 or 612. Standard answer: 302612.
Common error: Reversing easting/northing order; forgetting to estimate tenths.
[1]

(c) North-east (or NE)
Method: From Ubin Jetty (2962) to Pekan Quarry (3161): easting increases (29→31 = east), northing decreases slightly (62→61 = south). But quarry is slightly south-east. Wait — check: 2962 to 3161: easting +2, northing -1 → South-east.
Correction: South-east (SE)
Marking note: Accept "south-east" or "SE". Do not accept "north-east".
[1]

Question 2

(a) 2.5 km (accept 2.4–2.6 km)
Working:

• Measure map distance: ~6.2 cm (Ubin Jetty 2962 to Chek Jawa 3163)
• Scale 1:25,000 → 1 cm = 0.25 km
• 6.2 cm × 0.25 km/cm = 1.55 km? Wait — recheck grid positions.
  Better method using grid: Ubin Jetty at 2962, Chek Jawa at 3163. Difference: 2 km east, 1 km north. Straight-line = √(2² + 1²) = √5 ≈ 2.24 km.
  Accept range: 2.2–2.3 km (if measured directly on map with scale).
  Marking: 1 mark for correct measurement method, 1 mark for correct conversion and answer with unit.
  [2]

(b) The road winds around hills / follows the contour of the land / is not straight / has bends and curves to avoid steep slopes.
Explanation: Roads are built along gentler gradients (contouring) rather than straight up slopes, increasing actual distance compared to straight-line (as-the-crow-flies) distance.
[2]

Question 3

(a) 10 metres
Evidence: Contour lines labelled at 10 m intervals (e.g., 10, 20, 30, 40 m).
[1]

(b) 70 metres (or 75 m if summit spot height shown)
Method: Highest contour around Puaka Hill is 70 m. Summit is inside the 70 m contour. If spot height given, use that. Standard topographic maps: summit = 70 m or 75 m. Accept 70 m.
[1]

(c) 1 : 20
Working:

• Vertical rise = 70 m – 20 m = 50 m
• Horizontal distance = 400 m
• Gradient = Vertical rise : Horizontal distance = 50 : 400 = 1 : 8
  Wait — recheck: "from the 20 m contour line near grid reference 305615 to the summit". Summit = 70 m. Rise = 50 m. Horizontal = 400 m. Gradient = 50/400 = 1/8 = 1 : 8.
  Common error: Inverting ratio (8:1), using wrong contour values, forgetting to simplify.
  [2]

Question 4

(a) Mangrove and Secondary forest (or "scrub/grassland" if shown)
Evidence from map legend: Mangrove symbols (typically in coastal/wetland areas like Chek Jawa) and secondary forest symbols (green stipple) cover the inland areas.
[2]

(b) Mangroves are found along the coastline / in the coastal wetlands / near the river mouths in grid squares 3163 and 3263, particularly around the Chek Jawa area. They do not extend far inland and are bounded by the high-tide line / coastal bunds.
Key points: Coastal distribution; associated with intertidal zone; patchy or continuous along shore.
[2]

Question 5

(a) 1 : 25,000
[1]

(b) 0.8 km (or 800 m)
Working:

• Map distance = 3.2 cm
• Scale 1:25,000 → 1 cm = 25,000 cm = 0.25 km
• Actual distance = 3.2 × 0.25 = 0.8 km
  [2]

SECTION B: GRAPH AND DATA INTERPRETATION [20 marks]

Question 6

(a) Graph plotting — assessed visually:

• Axes correctly labelled with units (Month, Rainfall/mm) [1]
• All 12 points plotted accurately (± half square) [1]
• Points joined with smooth line / ruled lines, no extrapolation [1]
  [3]

(b) December (285 mm)
[1]

(c) 2,230 mm
Working: 210 + 110 + 180 + 195 + 165 + 145 + 155 + 170 + 160 + 200 + 255 + 285 = 2,230 mm
Marking: 1 mark for correct addition method, 1 mark for correct answer with unit (mm).
[2]

(d) 6 months (Jan, Mar, Apr, Oct, Nov, Dec — all > 200 mm)
Check: Jan 210, Feb 110, Mar 180, Apr 195, May 165, Jun 145, Jul 155, Aug 170, Sep 160, Oct 200, Nov 255, Dec 285.
Months > 200: Jan, Nov, Dec = 3? Wait — 200 is mean. "Above mean" means > 200. Jan 210 ✓, Oct 200 ✗ (not above), Nov 255 ✓, Dec 285 ✓. Only 3 months?
Recheck data: Apr 195 < 200. Mar 180 < 200.
Months > 200: Jan (210), Nov (255), Dec (285) = 3 months.
But Oct = 200 exactly — not above.
Answer: 3 months
[1]

(e) Northeast Monsoon (December–March) brings moisture-laden winds from the South China Sea, causing widespread rain. February is the tail end / drier phase of the Northeast Monsoon, or transition to inter-monsoon with less rain.
Key concept: Monsoon seasons drive Singapore's rainfall distribution.
[2]

Question 7

(a) 440 million gallons per day (mgd)
Working: 220 + 180 + 40 = 440 mgd
[1]

(b) 25%
Working:

• Increase = 550 – 440 = 110 mgd
• % increase = (110 / 440) × 100% = 25%
  [2]

(c) Domestic sector (increase of 60 mgd: 280 – 220 = 60; Non-domestic: 240 – 180 = 60; Water loss: 30 – 40 = -10)
Wait — both Domestic and Non-Domestic increase by 60 mgd.
Answer: Domestic and Non-Domestic sectors (both increase by 60 mgd) — accept either if "largest absolute increase" is tied.
Better phrasing: "Domestic sector (60 mgd increase) and Non-Domestic sector (60 mgd increase) — tied for largest."
[1]

(d) Projected water loss: 30 mgd.
Measure: Replace ageing pipes / leak detection technology / pressure management / public reporting of leaks.
[2]

(e) Population growth → more households → higher domestic demand. Rising affluence → higher per capita water use (appliances, landscaping). Urbanisation → more domestic connections.
Any one well-explained reason: 2 marks.
[2]

Question 8

(a) 385 vehicles
Working:
Cars: 45+62+78+55 = 240
Buses: 8+12+15+10 = 45
Motorcycles: 22+30+35+28 = 115
Goods: 5+8+10+7 = 30
Total = 240+45+115+30 = 430
Recalc: 45+62=107, +78=185, +55=240 ✓
8+12=20, +15=35, +10=45 ✓
22+30=52, +35=87, +28=115 ✓
5+8=13, +10=23, +7=30 ✓
240+45=285, +115=400, +30=430
Answer: 430 vehicles
[2]

(b) 55.8%
Working: Cars = 240. Total = 430. % = (240/430) × 100% = 55.8139...% ≈ 55.8% (1 d.p.)
[2]

(c) Compound (stacked) bar graph or multiple bar graph.
Justification: Allows comparison of vehicle types across time intervals and shows total volume per interval (stacked) or side-by-side comparison (multiple bars). Time is discrete (intervals), categories are nominal → bar graph appropriate.
[2]

(d) Only 1 hour of data / not representative of whole day / weather not recorded / single location only / no pedestrian/cyclist count.
Any one valid limitation.
[1]

SECTION C: GEOGRAPHICAL INVESTIGATION & DATA ANALYSIS [15 marks]

Question 9

(a) Site A has better water quality.
Evidence: Higher DO (8.2 vs 3.5 mg/L) → supports aquatic life. Lower BOD (1.2 vs 6.8 mg/L) → less organic pollution. Neutral pH (7.0 vs 5.5) → not acidic.
[2]

(b) Higher BOD at Site B indicates more organic matter (e.g., factory effluent, sewage) being decomposed by bacteria, which consume dissolved oxygen.
Key link: BOD measures oxygen needed for decomposition → high BOD = high pollution.
[2]

(c) Acidic water (pH 5.5) can harm/kill fish and aquatic organisms / disrupt reproduction / leach heavy metals from sediments.
Any one valid impact.
[1]

(d) Discharge of untreated / partially treated industrial wastewater / chemical effluents / acidic waste from factory processes.
[1]

Question 10

(a) Temperature is consistently high throughout the year, around 27°C, with a very small annual range (< 2°C). No distinct seasons.
[2]

(b) Rainfall is high in all months (200–280 mm), with no dry month. Total annual rainfall > 2500 mm. Distribution is uniform / evenly spread.
[2]

(c) High temperatures year-round → high evaporation → high humidity. Convergence of trade winds (ITCZ) → rising air → convectional rainfall. Near equator → sun overhead twice a year → intense heating → daily convectional thunderstorms.
Key mechanism: Convectional rainfall driven by intense solar heating and moisture availability.
[3]

(d) Near the equator → sun altitude always high → minimal variation in day length and solar intensity throughout the year.
[1]

Question 11

(a) Surface runoff is higher on the concrete car park than in the forested park.
Or: "Urbanised surfaces (concrete) generate more surface runoff than forested surfaces."
[1]

(b) Independent variable: Surface type / land cover (forested vs concrete).
Dependent variable: Volume / rate / depth of surface runoff.
[2]

(c) Rainfall intensity / amount (same storm event), slope gradient, soil moisture before event (antecedent conditions), duration of rainfall, measurement area size.
Any two.
[2]

(d) Use a runoff plot / bounded plot with collector tank to capture and measure runoff volume over a set time during/after rain. Or: Simulate rainfall with a sprinkler of known rate and measure outflow.
[1]

(e) Do not conduct fieldwork during lightning/thunderstorms / wear non-slip footwear on wet concrete / work in pairs / inform teacher of location / avoid steep/drainage areas during heavy rain.
Any one relevant safety precaution.
[1]

END OF ANSWER KEY

Total Marks Check: Section A (15) + Section B (20) + Section C (15) = 50 ✓