Question

Inner bark is composed of
A. Secondary xylem
B. Secondary phloem
C. Cork
D. Phellogen

Answer 1

The bark is the outermost layer of the stem and roots of woody plants. It is generally found in trees, shrubs and woody vines. It is used to make clothes. Canoes and ropes are used in surface painting and map-making. It is composed of tannins, lignin, suberin, polysaccharide and biopolymers.

Complete answer: The bark is a very complex structure that consists of cells that are formed from lateral meristems. The outer dead tissue (outer bark) forms a protective barrier between the plant axis and the abiotic and biotic environment. The inner tissue of the bark is composed of secondary phloem which helps to conduct food prepared by leaves to different parts of the plant. The secondary phloem is a tissue produced to the outside of the vascular cambium. It is a complex tissue that includes the axial and ray system. Secondary phloem tissues of both gymnosperms and dicotyledonous angiosperms are concerned mainly with the basipetal transport of sugars. The secondary phloem has the same origin as that of the secondary xylem, which is called the vascular cambium. Cells displaced towards the outside of the vascular cambium differentiate into the phloem. The secondary phloem can remain active for several growth cycles. It is a complex tissue system. It has sieve elements that are the same as that of tracheary elements. The bark plays an important role in the transportation of photosynthetic products in plant tissues. It is important in protecting against herbivory, fire and mechanical barriers act as insulation in cold conditions.
Hence, the correct answer is option B.

Note: The bark is helpful in regulating the temperature. It also helps in transporting nutrients and water throughout the plant body. It acts as a protective skin and protects the plant from animals and insects and from forest fires, storms and attacks from diseases and infections.