GAP Geographic Information Systems 3 — Questions and Answers
Question 1: Which GIS function is used to combine two or more layers to produce a new output based on their spatial relationships?
- Geocoding
- Overlay analysis (Correct answer)
- Datum transformation
- Feature symbolization
Correct answer: Overlay analysis
Overlay analysis intersects, unions, or clips multiple spatial layers to reveal relationships, such as which soil types overlap with flood-prone zones.
Question 2: What is the primary advantage of using GPS-enabled farm equipment linked to GIS software?
- It eliminates the need for soil testing
- It enables precise, geo-referenced recording of field operations and inputs (Correct answer)
- It automatically complies with all GAP record-keeping requirements
- It replaces the need for agronomist field visits
Correct answer: It enables precise, geo-referenced recording of field operations and inputs
GPS-enabled equipment logs the exact location of field operations, creating geo-referenced records of planting, spraying, and harvesting activities.
Question 3: Which term describes the process of assigning geographic coordinates to a street address or farm location?
- Georeferencing
- Geocoding (Correct answer)
- Digitizing
- Reprojection
Correct answer: Geocoding
Geocoding converts descriptive location information (addresses, place names) into coordinate pairs that can be mapped in a GIS.
Question 4: For GAP certification, a GIS-based field map must typically include which of the following?
- Crop futures pricing data
- Field boundaries, water sources, and adjacent land uses (Correct answer)
- Employee work schedules
- Equipment maintenance logs
Correct answer: Field boundaries, water sources, and adjacent land uses
GAP field maps must show field boundaries, nearby water sources, roads, and adjacent land uses to document risk factors and traceability information.
Question 5: What is the function of a coordinate reference system (CRS) in GIS?
- It assigns crop yield values to soil types
- It defines how spatial data is projected and located on the Earth's surface (Correct answer)
- It calculates the area of irrigation coverage
- It links sensor data to weather station records
Correct answer: It defines how spatial data is projected and located on the Earth's surface
A CRS (or spatial reference system) defines the mathematical relationship between map coordinates and real-world locations, ensuring layers align properly.
Question 6: A grower uses GIS to identify which fields are within 200 feet of a municipal water intake. This is an example of:
- Raster reclassification
- Proximity or buffer analysis (Correct answer)
- Kriging interpolation
- Network routing analysis
Correct answer: Proximity or buffer analysis
Proximity analysis (buffer analysis) identifies all features within a specified distance of a target feature, such as fields near a water intake.
Question 7: Which data collection method is most efficient for capturing the boundary of a large agricultural field in the field?
- Manual tape measurement and hand sketching
- GPS rover or GNSS device walked around the perimeter (Correct answer)
- Aerial photograph printed and digitized by hand
- Soil probe sampling at grid points
Correct answer: GPS rover or GNSS device walked around the perimeter
A GPS or GNSS rover records precise coordinates as an operator walks the field boundary, producing an accurate digital polygon in minutes.
GAP Geographic Information Systems 3
Which GIS function is used to combine two or more layers to produce a new output based on their spatial relationships?