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

TuitionGoWhere Practice Paper - Geography Secondary 1 SA2 Version 2

Answer Key and Marking Scheme

Total Marks: 50

Section A: Map Skills [15 marks]

Question 1

(a) 456789 (or equivalent correct 6-figure GR for Sembawang Park Jetty) [1]
Marking: 1 mark for correct 6-figure grid reference. Must read easting first (456), then northing (789). Accept ±1 in third/fifth digit.

(b) 4579 (or equivalent correct 4-figure GR for swimming complex) [1]
Marking: 1 mark for correct 4-figure grid reference. Must use bottom-left corner of grid square.

(c) 4.3 km (accept 4.2–4.4 km) [2]
Working:

• Measure map distance: ~10.8 cm (accept 10.5–11.0 cm)
• Scale 1:25,000 → 1 cm = 0.25 km
• Actual distance = 10.8 × 0.25 = 2.7 km
  Wait, recalculating: Grid squares are 1km × 1km. From 4578 to 4875 is 3 east, 3 south → diagonal ≈ 4.24 km. Accept 4.2–4.4 km. [2]
  Marking: 1 mark for correct measurement method, 1 mark for correct answer with units.

(d) 4 km² [2]
Working:

• Area on map = 2 km (E-W) × 2 km (N-S) = 4 grid squares
• Each grid square = 1 km × 1 km = 1 km²
• Total area = 4 × 1 = 4 km²
  Marking: 1 mark for correct method (counting grid squares or calculation), 1 mark for correct answer with units.

Question 2

(a) 10 metres [1]
Marking: 1 mark for correct contour interval. Read from map legend.

(b) 60 metres (or highest spot height/contour in 4577) [1]
Marking: 1 mark for correct height. Must identify highest contour line or spot height within the grid square.

(c) Relief description: [2]

• Generally low-lying and flat (0–20m) near the coast in 4676
• Gently undulating with low hills rising to 40–50m in 4776
• Contour lines are widely spaced indicating gentle slopes
  Marking: 1 mark for describing general relief (flat/low-lying), 1 mark for using contour evidence (spacing/height values).

(d) Reason for shipyard location: [2]

• Deep water access at coast for large vessels (map shows sea adjacent to shipyard)
• Flat land for construction of facilities (contours widely spaced/low relief)
• Proximity to shipping lanes (Straits of Johor visible on map)
  Marking: 1 mark for identifying coastal location advantage, 1 mark for map evidence (deep water/flat land/shipping lanes).

Question 3

(a) North-west (or NW) [1]
Marking: 1 mark for correct cardinal/intercardinal direction from jetty (4578) to mangrove (4478).

(b) Why mangroves at this location: [3]

• Sheltered coastline (map shows bay/indentation at 4478) protects seedlings from strong waves
• Muddy substrate (intertidal zone shown by coastline symbol) allows root anchoring
• Brackish water from river mouth (stream symbol entering sea at 4478) provides suitable salinity
• Low-lying flat land (contours at 0–10m) allows tidal inundation
  Marking: 1 mark each for any three valid points with map evidence. Must link map symbol/feature to mangrove requirement.

Section B: Graph and Data Skills [20 marks]

Question 4

(a) December [1]
Marking: 1 mark for correct month (highest bar at 280mm).

(b) 170 mm [1]
Working: Wettest = Dec (280mm), Driest = Feb (110mm). Difference = 280 – 110 = 170 mm.
Marking: 1 mark for correct calculation with units.

(c) 184.6 mm (accept 185 mm) [2]
Working:

• Total = 210+110+180+190+160+150+155+170+165+195+250+280 = 2215 mm
• Mean = 2215 ÷ 12 = 184.58 ≈ 184.6 mm
  Marking: 1 mark for correct summation/total, 1 mark for correct division and answer with units.

(d) Trend June–December: [2]

• Generally increasing from June (150mm) to December (280mm)
• Fluctuations in between: dip in July (155mm), rise to Aug (170mm), slight dip Sep (165mm), sharp rise Oct (195mm)–Dec (280mm)
  Marking: 1 mark for overall trend (increasing), 1 mark for describing fluctuations with data.

(e) Reason for high December rainfall: [2]

• Northeast Monsoon (Dec–Mar) brings moisture-laden winds from South China Sea
• Convergence of winds near equator causes uplift and convectional rainfall
  Marking: 1 mark for identifying Northeast Monsoon, 1 mark for mechanism (moisture/convection).

Question 5

(a) Site A (Upstream) [3]
Evidence (any two):

• Highest Dissolved Oxygen (7.2–8.1 mg/L) → supports aquatic life
• Lowest BOD (1.2–2.0 mg/L) → less organic pollution
• Lowest Turbidity (5–12 NTU) → clearer water, better light penetration
• Near-neutral pH (6.8–7.2) → optimal for most organisms
  Marking: 1 mark for identifying Site A, 1 mark each for two distinct evidence points with data.

(b) Why BOD increases A→C: [3]

• Site A (forested): Minimal human activity, low organic waste input
• Site B (residential): Domestic sewage, detergents, food waste from households enter river
• Site C (industrial): Industrial effluent, chemical/organic waste from factories increases decomposer activity
• Decomposers break down organic matter → consume oxygen → higher BOD
  Marking: 1 mark for identifying pollution sources at each site, 1 mark for linking to organic waste, 1 mark for explaining decomposer-oxygen link.

(c) Human activities causing high turbidity at Site C: [2]

• Construction/earthworks → soil erosion → sediment runoff
• Industrial discharge → suspended solids in effluent
• Deforestation/land clearance upstream → exposed soil washed into river
  Marking: 1 mark each for two distinct human activities linked to sediment/solids.

(d) Impact of decreasing pH at Site C: [1]

• Acidic water harms fish gills, reduces reproduction, kills acid-sensitive species (e.g., certain invertebrates), dissolves heavy metals making them toxic
  Marking: 1 mark for any valid ecological impact of acidification.

Question 6

(a) 2.5°C [1]
Working: Highest temp = 28.5°C (May/Jun), Lowest = 26.0°C (Dec). Range = 28.5 – 26.0 = 2.5°C.
Marking: 1 mark for correct calculation with units.

(b) 2240 mm [1]
Working: Sum of all monthly rainfall = 220+150+180+200+170+140+130+150+160+210+250+280 = 2240 mm.
Marking: 1 mark for correct total with units.

(c) Tropical Rainforest Climate (or Equatorial Climate / Af) [1]
Marking: 1 mark for correct climate type.

(d) Why this climate at 1°N, 103°E: [3]

• Near equator (1°N) → high solar insolation year-round → consistently high temperatures (small annual range)
• Intertropical Convergence Zone (ITCZ) passes overhead twice yearly → convectional rainfall throughout year
• Maritime location (surrounded by sea) → high humidity, moisture supply for rainfall
• No distinct dry month (all months > 130mm) → supports tropical rainforest vegetation
  Marking: 1 mark for latitude/insolation link, 1 mark for ITCZ/convection mechanism, 1 mark for maritime influence/no dry season.

Section C: Data Interpretation and Geographical Skills [15 marks]

Question 7

(a) Central Area [1]
Marking: 1 mark for correct planning area (highest x-value at 28,500).

(b) Relationship: [2]

• Negative correlation / inverse relationship
• As population density increases, green space per capita decreases
  Marking: 1 mark for identifying negative/inverse relationship, 1 mark for describing direction of both variables.

(c) Reason for relationship: [2]

• Land scarcity in high-density areas → more land allocated for housing/commercial use → less land for parks/green space
• Competition for land drives up value, making green space economically "less viable" in dense urban cores
  Marking: 1 mark for land scarcity/competition concept, 1 mark for linking to land use allocation.

(d) Target for Marine Parade: [3]

• Suggested target: 25–35 m²/person
• Justification: Current = 18 m²/person. Bishan (similar density ~15,800) has 38 m²; Tampines (higher density 18,200) has 32 m². A target of ~30 m² is realistic if land is reallocated from car parks/roads or rooftop gardens added.
  Marking: 1 mark for realistic target value (25–35), 1 mark for using Figure 4 comparison data, 1 mark for feasible justification (policy/land use strategy).

Question 8

(a) Salinity increases from Station 1 (0.5 ppt) to Station 3 (32.0 ppt) [1]
Marking: 1 mark for correct trend with data.

(b) Trend in Dissolved Oxygen (decreasing): [3]

• Station 1 (freshwater): Higher DO solubility in fresh water; photosynthesis by freshwater plants/algae adds oxygen
• Station 2 (brackish): Reduced oxygen solubility in saltier water; decomposition of organic matter from mangroves consumes oxygen
• Station 3 (seawater): Lowest oxygen solubility at high salinity/temperature; respiration by marine organisms; limited photosynthesis at depth
  Marking: 1 mark for solubility-salinity relationship, 1 mark for biological processes (photosynthesis/respiration/decomposition), 1 mark for applying to all three stations.

(c) Transect sampling: [2]

• Advantage: Shows spatial change/gradient across environmental zones (e.g., landward to seaward) efficiently
• Limitation: Only one line → may miss variability; not representative of whole area; edge effects at boundaries
  Marking: 1 mark for valid advantage, 1 mark for valid limitation.

(d) Improve reliability: [2]

• Repeat measurements at each station (multiple readings) and calculate average
• Use calibrated instruments / standardised methods (e.g., same time of day, same depth)
• Increase sample points (more stations / replicate transects)
  Marking: 1 mark for valid method (replication/calibration/standardisation), 1 mark for explaining how it improves reliability.

Question 9

(a) 45% [1]
Working: 1990 = 65%, 2020 = 20%. Decrease = 65 – 20 = 45%.
Marking: 1 mark for correct calculation with % sign.

(b) Agriculture [1]
Working: Agriculture: 12% → 30% = +18%. Urban: 5% → 18% = +13%. Secondary Forest: 15% → 25% = +10%. Agriculture has largest absolute increase.
Marking: 1 mark for correct category.

(c) Urban land use trend: [2]

• Steady increase from 5% (1990) to 18% (2020)
• Rate accelerates: +3% (1990–2000), +4% (2000–2010), +6% (2010–2020)
  Marking: 1 mark for overall increase, 1 mark for accelerating rate with data.

(d) Environmental impacts of primary forest loss: [4]

• Biodiversity loss: Primary forest = unique habitats/endemic species → extinction risk
• Carbon emissions: Trees store carbon → deforestation releases CO₂ → climate change
• Soil erosion: Removal of canopy → rain hits bare soil → washes/blows away topsoil
• Disrupted water cycle: Less transpiration → reduced rainfall; loss of watershed protection → flooding/droughts
• Impact on indigenous communities: Loss of livelihoods, cultural heritage
  Marking: 1 mark each for any four distinct impacts with explanation. Must link to primary forest characteristics.

(e) Sustainable strategy: [2]

• Gazette as protected area (e.g., national park) with strict enforcement against illegal logging/encroachment
• Community-based conservation: Involve indigenous/local communities in monitoring and sustainable use (e.g., ecotourism, non-timber forest products)
• Corridor creation: Connect fragmented patches to allow wildlife movement and gene flow
  Marking: 1 mark for valid strategy, 1 mark for explaining sustainability aspect (long-term, balances protection/use).

Question 10

(a) Middle course (or Lower course – accept both as meanders form in middle and extend to lower) [1]
Marking: 1 mark for correct course. Middle course is most typical answer.

(b) Formation of meanders: [3]

• Lateral erosion dominates in middle course due to gentler gradient and higher discharge
• Helicoidal flow (corkscrew current) → erosion on outer bank (river cliff) → deposition on inner bank (slip-off slope)
• Positive feedback: Erosion deepens outer bend → flow concentrates → more erosion → bend migrates outward
• Riffle-pool sequence develops → meanders become more sinuous over time
  Marking: 1 mark for lateral erosion/gradient context, 1 mark for helicoidal flow mechanism, 1 mark for erosion-deposition feedback/migration.

(c) Why vertical exaggeration: [2]

• Vertical relief (height changes) is very small compared to horizontal distance (km)
• Without exaggeration, profile would appear almost flat → features invisible (valleys, gradients)
• Exaggeration (e.g., 10×) makes slopes, valley shapes, gradient changes visible for analysis
  Marking: 1 mark for scale disparity reason, 1 mark for purpose (visibility of features).

(d) Channel difference (upper vs lower): [2]

• Upper course: Narrow, shallow, rough/rocky bed, steep gradient, turbulent flow, V-shaped valley
• Lower course: Wide, deep, smooth/silt bed, gentle gradient, laminar flow, floodplain
  Marking: 1 mark for upper course characteristic, 1 mark for contrasting lower course characteristic. Must be paired comparison.

END OF MARKING SCHEME

Total Marks: 50