CATS Biology and Physiology 2

Question 1

What is the primary function of lenticels on a tree's bark?

Accepted Answer

Gas exchange between inner tissues and atmosphere

Answer

Lenticels are porous openings in bark that allow oxygen and carbon dioxide to pass between the atmosphere and the living cells beneath.

Question 2

Which vascular tissue is responsible for transporting sugars produced by photosynthesis downward through the tree?

Accepted Answer

Phloem

Answer

Phloem conducts photosynthates (sugars) from leaves to roots and other non-photosynthetic tissues through sieve tube elements.

Question 3

In trees, what is the zone called where new xylem and phloem cells are produced?

Accepted Answer

Vascular cambium

Answer

The vascular cambium is the meristematic layer that divides to produce secondary xylem (wood) inward and secondary phloem outward.

Question 4

What happens to a tree's stomata during periods of drought stress?

Accepted Answer

They close to reduce water loss

Answer

Guard cells lose turgor pressure during drought, causing stomata to close and reducing transpiration, though this also limits photosynthesis.

Question 5

Which anatomical feature distinguishes hardwood (angiosperm) trees from softwood (gymnosperm) trees under a microscope?

Accepted Answer

Presence of vessels (pores)

Answer

Hardwoods contain vessels (large-diameter pores) for water conduction, while softwoods rely solely on tracheids for this function.

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