CATS - Certified Arborist Tree Service of Albuquerque Tree Biology and Physiology Questions and Answers 1 — Questions and Answers
Question 1: Which of the following describes the primary physiological functions of stomata on a tree's leaves?
- To absorb water and nutrients from the atmosphere.
- To anchor the leaf to the stem and transport sugars.
- To regulate gas exchange and control water loss through transpiration. (Correct answer)
- To produce chlorophyll for photosynthesis.
Correct answer: To regulate gas exchange and control water loss through transpiration.
Stomata are small pores, typically on the underside of leaves, that open and close to allow carbon dioxide to enter for photosynthesis and to allow oxygen and water vapor to exit. This process of water vapor exiting is called transpiration, which is a critical part of water movement through the tree.
Question 2: A certified arborist is explaining to a client how trees move sugars from the leaves to other parts of the tree, like the roots and fruit. In this process, the mature leaves are considered a 'source.' What is the corresponding term for the roots, fruit, or growing tips that receive these sugars?
- A conduit
- A sink (Correct answer)
- A meristem
- A reservoir
Correct answer: A sink
In phloem translocation, a 'source' is an area that produces or supplies excess sugars (e.g., mature leaves). A 'sink' is an area of active growth or storage that requires more energy than it produces, such as roots, developing fruits, or new shoots, and therefore imports sugars.
Question 3: Which of the following tree tissues is a lateral meristem responsible for secondary growth, which results in the thickening of the trunk and branches?
- Xylem
- Phloem
- Cortex
- Cambium (Correct answer)
Correct answer: Cambium
The cambium is a thin layer of actively dividing cells located between the xylem and phloem. Its division produces new xylem cells to the inside and new phloem cells to the outside, causing the stem and branches to increase in diameter (girth).
Question 4: When a tree is wounded, it responds by forming chemical and physical barriers to resist the spread of decay. This defensive process, described by Dr. Alex Shigo, is known as:
- Hydraulic lift
- Photosynthetic prioritization
- Compartmentalization of Decay in Trees (CODIT) (Correct answer)
- Apical dominance assertion
Correct answer: Compartmentalization of Decay in Trees (CODIT)
Compartmentalization of Decay in Trees (CODIT) is the model that describes how trees 'wall off' or compartmentalize injured and infected tissue to prevent the decay from spreading into healthy wood. This process involves four 'walls' that form barriers against the pathogen.
Question 5: A tree's total energy balance depends on the relationship between photosynthesis and respiration. Which statement accurately contrasts these two processes?
- Photosynthesis occurs only in the dark, while respiration occurs only in the light.
- Both processes produce oxygen and consume carbon dioxide.
- Photosynthesis stores energy by producing sugars, while respiration releases energy by consuming sugars. (Correct answer)
- Photosynthesis happens in the roots, while respiration happens in the leaves.
Correct answer: Photosynthesis stores energy by producing sugars, while respiration releases energy by consuming sugars.
Photosynthesis uses light energy to convert carbon dioxide and water into energy-rich sugars (glucose), effectively storing energy. Respiration is the process by which the tree breaks down those sugars to release the stored energy for growth, maintenance, and other life processes.
Question 6: Which of the following best describes the symbiotic relationship known as mycorrhizae?
- A parasitic fungus that attacks and consumes tree roots, leading to decline.
- A mutually beneficial association between fungi and tree roots where the fungus helps the tree absorb water and nutrients in exchange for sugars. (Correct answer)
- A type of bacteria that lives on leaves and helps protect the tree from airborne pathogens.
- An insect that lives in the bark of a tree and helps ward off wood-boring pests.
Correct answer: A mutually beneficial association between fungi and tree roots where the fungus helps the tree absorb water and nutrients in exchange for sugars.
Mycorrhizae are a classic example of a symbiotic, or mutually beneficial, relationship. The fungal hyphae vastly expand the surface area of the tree's root system, enhancing water and nutrient uptake, while the tree provides the fungus with essential carbohydrates (sugars) produced during photosynthesis.
CATS - Certified Arborist Tree Service of Albuquerque Tree Biology and Physiology Questions and Answers 1
Which of the following describes the primary physiological functions of stomata on a tree's leaves?