ISA Tree Biology and Physiology 3

Question 1

Which wood characteristic is associated with the earlywood formed at the beginning of a growing season?

Accepted Answer

Large-diameter, thin-walled cells with wide lumens

Answer

Earlywood (springwood) is characterized by large-diameter, thin-walled tracheids or vessels that efficiently conduct large volumes of water during peak growing season.

Question 2

What is the primary carbon-fixing reaction in C3 photosynthesis used by most temperate trees?

Accepted Answer

CO2 is fixed by RuBisCO into a 3-carbon compound

Answer

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.

Question 3

Which layer of the cell wall is shared between adjacent cells and acts as the cementing layer?

Accepted Answer

Middle lamella

Answer

The middle lamella, composed mainly of calcium pectate, is the outermost layer shared between adjacent cells and holds them together.

Question 4

What phenomenon occurs when a tree's transpiration demand exceeds the soil's ability to supply water, leading to wilting?

Accepted Answer

Permanent wilting point

Answer

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.

Question 5

In which tissue are sieve tube elements and companion cells found?

Accepted Answer

Phloem

Answer

Sieve tube elements and companion cells are the defining cell types of phloem, which conducts photosynthates from source tissues to sink tissues.

(ISA) ISA Certified Arborist Practice Test

(ISA) ISA Certified Arborist Practice Test

ISA Tree Biology and Physiology 3