Tree Biology and Physiology Flashcards
7 cards from real ISA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Tree Biology and Physiology flashcards as text
What is the primary mechanism by which water moves upward through the xylem in tall trees?
Answer: Cohesion-tension generated by transpiration pulls water columns upward
The cohesion-tension mechanism relies on the cohesive properties of water and the tension (negative pressure) created by transpiration to pull continuous water columns from roots to leaves.
What term describes the dormancy-breaking requirement of many temperate trees that need a period of cold temperatures before buds can flush in spring?
Answer: Chilling requirement
The chilling requirement is the number of hours below a threshold temperature (typically ~7°C) needed to break endodormancy and allow normal spring bud break.
In which direction does the pressure-flow hypothesis predict photosynthate movement in the phloem?
Answer: From areas of high solute concentration (source) to low concentration (sink)
The pressure-flow hypothesis states that photosynthates move from source tissues (high sugar concentration) to sink tissues (low sugar concentration) along a pressure gradient.
What is 'phenology' in the context of tree biology?
Answer: The study of seasonal timing of biological events such as bud break and leaf fall
Phenology is the study of cyclic and seasonal natural phenomena, including tree events like bud break, flowering, leaf-out, and leaf senescence, and how they relate to climate.
What happens to a tree's stomata when guard cell turgor decreases?
Answer: Stomata close, reducing transpiration and CO2 uptake
When guard cells lose turgor (water), they become flaccid and the stomatal pore closes, which reduces both water loss through transpiration and CO2 uptake for photosynthesis.
Which of the following best describes 'sapwood' in a mature tree?
Answer: The outermost, living wood that actively conducts water and stores carbohydrates
Sapwood is the outer, living portion of the wood that contains functional xylem conducting water and dissolved minerals and parenchyma cells storing carbohydrates.
What is the function of root hairs on a tree's fine roots?
Answer: Greatly increase the surface area for water and nutrient absorption
Root hairs are thin-walled extensions of epidermal cells that dramatically increase root surface area, enhancing the uptake of water and dissolved mineral nutrients from soil.