GAP Geographic Information Systems 2 — Questions and Answers
Question 1: Which GIS data model stores geographic features as points, lines, and polygons?
- Raster model
- Vector model (Correct answer)
- TIN model
- Grid model
Correct answer: Vector model
The vector data model represents geographic features as discrete points, lines, and polygons with associated attribute data.
Question 2: In GAP agriculture, what does a soil survey GIS layer typically help farmers determine?
- Pest migration patterns
- Crop suitability and drainage potential (Correct answer)
- Market prices for commodities
- Labor scheduling requirements
Correct answer: Crop suitability and drainage potential
Soil survey GIS layers provide data on soil type, texture, and drainage class, helping farmers assess which crops are best suited for specific fields.
Question 3: What is the purpose of a buffer zone analysis in agricultural GIS?
- To calculate crop yield averages
- To identify areas within a set distance of a feature such as a water body (Correct answer)
- To convert raster data to vector format
- To merge multiple attribute tables
Correct answer: To identify areas within a set distance of a feature such as a water body
Buffer analysis creates zones around features (e.g., streams or wells) to identify setback distances required for pesticide applications or other activities.
Question 4: Which satellite imagery resolution range is most commonly used for field-level precision agriculture mapping?
- 1 km – 10 km
- 100 m – 500 m
- 0.5 m – 10 m (Correct answer)
- 10 km – 50 km
Correct answer: 0.5 m – 10 m
Sub-meter to 10-meter resolution imagery provides enough detail to distinguish individual field zones, crop rows, and small landscape features.
Question 5: What does NDVI measure in remote sensing applications for agriculture?
- Nitrogen content in irrigation water
- Vegetation health and density using near-infrared and red bands (Correct answer)
- Soil pH levels across a field
- Drainage tile depth and spacing
Correct answer: Vegetation health and density using near-infrared and red bands
NDVI (Normalized Difference Vegetation Index) quantifies plant health by comparing near-infrared reflectance (high in healthy plants) to red light reflectance.
Question 6: A farmer wants to map variable-rate fertilizer application zones. Which GIS output is most directly used for this purpose?
- A topographic contour map
- A management zone map based on yield and soil data (Correct answer)
- A land-use/land-cover classification
- A road network distance analysis
Correct answer: A management zone map based on yield and soil data
Management zone maps delineate field areas with similar productivity potential, guiding variable-rate application of inputs to match crop needs.
Question 7: In GIS, what is a digital elevation model (DEM) used for in farm management?
- Tracking livestock GPS collars
- Modeling water flow, slope, and drainage patterns across fields (Correct answer)
- Scheduling irrigation based on evapotranspiration
- Identifying pest hot spots from trap counts
Correct answer: Modeling water flow, slope, and drainage patterns across fields
A DEM provides terrain elevation data used to derive slope, aspect, and flow accumulation, which inform drainage planning and erosion risk assessment.
GAP Geographic Information Systems 2
Which GIS data model stores geographic features as points, lines, and polygons?