Question

The term bark refers to

• A. Phellem, phelloderm, and vascular cambium
• B. Periderm and secondary xylem
• C. Cork cambium and cork
• D. Phellogen, phellum, phelloderm, and secondary phloem

Answer 1

The correct option is D

Phellogen, phellum, phelloderm, and secondary phloem

The correct option is D.

Explanation of the correct option:

1. Bark refers to the vascular cambium exterior of all the tissue types (Phellogen, phellem, Phelloderm, and secondary phloem).
2. Vascular cambium is a meristematic layer that separates the xylem and phloem.
3. Phellogen: Due to vascular cambium's continuously dividing ability, a thick layer of meristematic tissue develops in the cortex region called Phellogen.
4. Phellum: The Phellogen cuts off the cells on both sides of the cortex, and the outer cells differentiate into cork or phellem
5. Phelloderm: The Phellogen cuts off the cells on both sides of the cortex, and the inner cells differentiate into the secondary cortex or Phelloderm.
6. Secondary phloem: The cambial ring activity cuts off new cells towards the outer and inner side of the cambial ring, the cells that cut off towards the periphery are called secondary phloem.
7. Due to the continuous formation of the primary and secondary xylem, the primary and secondary phloem gets crushed into a compact mass.
8. Thus bark is composed of Phellogen, Phellum, Phelloderm, and Secondary phloem.

Final answer: The term bark refers to Phellogen, Phellum, Phelloderm, and Secondary phloem.