B.F. Bachelor of Forestry Wood Science and Technology 1 — Questions and Answers
Question 1: What is 'specific gravity' of wood and why is it important?
- The moisture content of green wood
- The ratio of wood density to the density of water, indicating strength and suitability for end uses (Correct answer)
- The number of growth rings per inch
- The percentage of heartwood in a log
Correct answer: The ratio of wood density to the density of water, indicating strength and suitability for end uses
Specific gravity is the ratio of oven-dry wood mass to the mass of water displaced, and it is the best single predictor of most wood mechanical properties.
Question 2: What is 'heartwood' in a tree stem?
- The outermost living layer of wood just inside the bark
- The inner, non-living core of xylem that no longer conducts water (Correct answer)
- The thin layer of cells between bark and wood
- The zone of active cell division in a tree
Correct answer: The inner, non-living core of xylem that no longer conducts water
Heartwood is the inner, non-conductive core of xylem that has undergone chemical changes, often making it more durable and darker than sapwood.
Question 3: What causes wood to shrink and swell?
- Changes in temperature only
- Changes in moisture content below the fiber saturation point (Correct answer)
- Photosynthetic activity in living cells
- Mechanical stress during tree growth
Correct answer: Changes in moisture content below the fiber saturation point
Wood shrinks as it loses moisture below the fiber saturation point and swells as it absorbs moisture, because water molecules occupy space within cell walls.
Question 4: What is 'lumber grading' used for in the wood products industry?
- Determining the species of harvested trees
- Classifying sawn lumber by quality characteristics to determine appropriate end uses (Correct answer)
- Measuring the carbon content of wood
- Setting the price of standing timber in forest auctions
Correct answer: Classifying sawn lumber by quality characteristics to determine appropriate end uses
Lumber grading classifies sawn wood by defects, strength, and appearance characteristics to match lumber quality to appropriate structural or aesthetic end uses.
Question 5: Which component of wood is primarily responsible for its structural strength?
- Lignin only
- Cellulose microfibrils (Correct answer)
- Extractives
- Resin canals
Correct answer: Cellulose microfibrils
Cellulose microfibrils provide the primary structural reinforcement in wood cell walls, giving wood its tensile strength and stiffness.
Question 6: What is 'kiln drying' used for in wood processing?
- Treating wood with preservatives to prevent insect attack
- Using controlled heat and humidity to reduce wood moisture content to desired levels (Correct answer)
- Removing bark from logs before sawing
- Sorting lumber by species in a mill
Correct answer: Using controlled heat and humidity to reduce wood moisture content to desired levels
Kiln drying uses controlled temperature and humidity in enclosed chambers to reduce wood moisture content rapidly and uniformly for manufacturing and stability.
B.F. Bachelor of Forestry Wood Science and Technology 1
What is 'specific gravity' of wood and why is it important?