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
Which wood characteristic is associated with the earlywood formed at the beginning of a growing season?
Answer: Large-diameter, thin-walled cells with wide lumens
Earlywood (springwood) is characterized by large-diameter, thin-walled tracheids or vessels that efficiently conduct large volumes of water during peak growing season.
What is the primary carbon-fixing reaction in C3 photosynthesis used by most temperate trees?
Answer: CO2 is fixed by RuBisCO into a 3-carbon compound
In C3 photosynthesis, RuBisCO fixes CO2 into a 3-carbon compound (3-phosphoglycerate) as the first stable product; this pathway is used by most broadleaf and conifer trees.
Which layer of the cell wall is shared between adjacent cells and acts as the cementing layer?
Answer: Middle lamella
The middle lamella, composed mainly of calcium pectate, is the outermost layer shared between adjacent cells and holds them together.
What phenomenon occurs when a tree's transpiration demand exceeds the soil's ability to supply water, leading to wilting?
Answer: Permanent wilting point
The permanent wilting point is the soil moisture level at which the tree can no longer extract sufficient water and wilting becomes irreversible without rewatering.
In which tissue are sieve tube elements and companion cells found?
Answer: Phloem
Sieve tube elements and companion cells are the defining cell types of phloem, which conducts photosynthates from source tissues to sink tissues.
What is 'girdling' and why is it fatal to trees?
Answer: Complete removal of bark around the circumference, cutting off phloem transport
Girdling removes a complete ring of bark, severing the phloem and preventing sugar transport from the canopy to roots, which eventually starves and kills the root system.
Which of the following describes the function of mycorrhizal fungi on tree roots?
Answer: They extend effective root surface area and enhance nutrient uptake
Mycorrhizal fungi form mutualistic associations with tree roots, dramatically extending their effective surface area and improving uptake of water, phosphorus, and other nutrients.