Certified Arborist Test Tree Biology and Physiology Questions and Answers — Questions and Answers
Question 1: Which of the following describes the primary function of phloem tissue in a tree?
- Transporting water and minerals from the roots to the leaves.
- Providing structural support to the trunk and branches.
- Transporting sugars from the leaves to other parts of the tree. (Correct answer)
- Creating new cells for secondary growth (girth).
Correct answer: Transporting sugars from the leaves to other parts of the tree.
The phloem is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis, known as photosynthates, in particular the sugar sucrose, to parts of the plant where needed. This transport process is called translocation.
Question 2: A mature oak tree in a parking lot island is showing signs of stress, including leaf scorch and premature fall coloration. The soil is heavily compacted. Which physiological process is most directly inhibited by the soil compaction?
- Photosynthesis
- Translocation
- Respiration in the roots (Correct answer)
- Apical dominance
Correct answer: Respiration in the roots
Soil compaction reduces pore space, which limits the availability of oxygen. Tree roots require oxygen to perform respiration, the process of converting sugars into energy for growth and nutrient uptake. Without adequate oxygen, root function declines, leading to poor water and nutrient absorption and overall tree stress.
Question 3: The plant hormone primarily responsible for promoting cell division and found in high concentrations in root tips is:
- Auxin
- Gibberellin
- Abscisic acid
- Cytokinin (Correct answer)
Correct answer: Cytokinin
Cytokinins are a class of plant hormones that promote cell division (cytokinesis) in plant roots and shoots. They are involved in cell growth and differentiation, affecting apical dominance, axillary bud growth, and leaf senescence.
Question 4: According to the CODIT model (Compartmentalization of Decay in Trees), which 'wall' is the strongest and most effective at stopping the spread of decay?
- Wall 1, which plugs xylem vessels above and below the wound.
- Wall 2, which is formed by the latewood cells of each growth ring.
- Wall 4, the barrier zone formed by new growth after the injury. (Correct answer)
- Wall 3, which consists of ray cells that run radially.
Correct answer: Wall 4, the barrier zone formed by new growth after the injury.
CODIT describes four walls that trees form to resist the spread of decay. Wall 4 is the new protective wall formed by the cambium after the tree is wounded. It is considered the strongest barrier because it separates the tissue present at the time of wounding from the new tissue that forms subsequently.
Question 5: Transpiration is the process of water movement through a tree and its evaporation from aerial parts. Which of the following environmental conditions would most likely DECREASE the rate of transpiration?
- High wind speed
- High soil moisture
- Low relative humidity
- High relative humidity (Correct answer)
Correct answer: High relative humidity
Transpiration is driven by the water potential gradient between the moist interior of the leaf and the drier air outside. High relative humidity means the air is already saturated with water vapor, which reduces the steepness of this gradient and therefore slows the rate of evaporation from the leaves.
Question 6: Photosynthesis and respiration are two critical physiological processes. Which statement accurately compares them?
- Photosynthesis occurs only in the dark, while respiration occurs only in the light.
- Photosynthesis stores energy by creating sugars, while respiration releases energy by breaking down sugars. (Correct answer)
- Both processes consume oxygen and release carbon dioxide.
- Respiration occurs only in the leaves, while photosynthesis occurs in all living cells.
Correct answer: Photosynthesis stores energy by creating sugars, while respiration releases energy by breaking down sugars.
Photosynthesis uses light energy to convert carbon dioxide and water into energy-rich sugars (food), storing energy. Respiration is the process by which cells break down these sugars to release the stored energy for use in growth and metabolism. While photosynthesis is light-dependent, respiration occurs continuously in all living cells, day and night.
Certified Arborist Test Tree Biology and Physiology Questions and Answers
Which of the following describes the primary function of phloem tissue in a tree?