CATS Biology and Physiology 3 — Questions and Answers
Question 1: What is CODIT (Compartmentalization of Decay in Trees) primarily used to describe?
- How trees absorb nutrients through bark
- How trees chemically wall off wounded or infected wood (Correct answer)
- How annual rings form in response to climate
- How trees transport water during drought
Correct answer: How trees chemically wall off wounded or infected wood
CODIT describes the four walls trees use to chemically and structurally limit the spread of decay organisms into healthy wood after injury.
Question 2: In the CODIT model, which wall is considered the strongest barrier against decay spread?
- Wall 1 — blocks upward/downward spread
- Wall 2 — blocks inward spread
- Wall 3 — blocks lateral spread
- Wall 4 — separates old wood from new growth (Correct answer)
Correct answer: Wall 4 — separates old wood from new growth
Wall 4, formed by the vascular cambium, is the strongest CODIT barrier and separates wood present at the time of wounding from new wood formed afterward.
Question 3: What is the term for the boundary zone of discolored wood that forms around a wound before callus tissue develops?
- Reaction zone (Correct answer)
- Wetwood
- Callus roll
- Sapwood interface
Correct answer: Reaction zone
The reaction zone is chemically altered wood surrounding a wound that forms the initial defensive barrier against pathogen spread.
Question 4: Which of the following best describes 'included bark' in tree structure?
- Bark embedded between two codominant stems (Correct answer)
- Dead outer bark layers on mature trees
- Cork tissue produced by phellogen
- Bark formed inside a wound callus
Correct answer: Bark embedded between two codominant stems
Included bark occurs when bark tissue becomes embedded between two codominant stems, creating a structurally weak union prone to failure.
Question 5: What term describes the annual addition of new wood by the vascular cambium that produces visible growth rings?
- Primary growth
- Apical elongation
- Secondary growth (Correct answer)
- Meristematic division
Correct answer: Secondary growth
Secondary growth refers to the increase in girth produced by the vascular cambium, creating successive layers of xylem and phloem visible as annual rings.
Question 6: What causes the difference in color between heartwood and sapwood?
- Heartwood contains active xylem vessels still carrying water
- Heartwood is impregnated with extractives as older sapwood cells die (Correct answer)
- Sapwood is colored by chlorophyll near the bark
- Heartwood forms only in softwood species
Correct answer: Heartwood is impregnated with extractives as older sapwood cells die
As inner sapwood cells die and cease water transport, they accumulate tannins, resins, and other extractives that give heartwood its darker color and increased durability.
Question 7: What is the function of root hairs on fine tree roots?
- Anchoring the tree against wind
- Storing carbohydrates for winter dormancy
- Dramatically increasing water and mineral absorption surface area (Correct answer)
- Producing mycorrhizal associations
Correct answer: Dramatically increasing water and mineral absorption surface area
Root hairs are single-cell extensions of epidermal cells that vastly increase the absorptive surface area, improving uptake of water and dissolved minerals from soil.
CATS Biology and Physiology 3
What is CODIT (Compartmentalization of Decay in Trees) primarily used to describe?