Question

From the image given below. Identify the parts (i), (ii), (iii) and (iv) respectively.

• A. Epidermis, Endodermis, Cambium, Pericycle
• B. Epidermis, Endodermis, Pericycle, Protoxylem
• C. Epidermis, Pericycle, Cambium, Phloem
• D. Epidermis, Cortical layer, Endodermis, Protoxylem

Answer 1

The correct option is B Epidermis, Endodermis, Pericycle, Protoxylem

The given image represents a transverse section of a primary dicot stem. A typical primary dicot stem shows the following zones from outside to inside:

• Epidermis: Outermost layer of the plant made up of parenchymatous cells. These may bear stem hair called trichomes.
• Hypodermis: 3-4 layered made up of collenchymatous cells.
• General cortex: Several layers thick and made up of parenchymatous cells.
• Endodermis: Single layered with barrel-shaped cells. Cells show deposition of starch grains as food reserves so it is also called as the starch sheath.
• Pericycle: The layer following the endodermis. It is made up of both parenchyma and sclerenchyma
• Vascular bundles: consists of xylem and phloem arranged in a ring-like fashion. They are conjoint, collateral and open. Protoxylem lies towards the pith or centre while metaxylem towards the periphery ( endarch) condition.
• Cambium: Present in the form of a narrow strip between xylem and phloem in a vascular bundle (intrafascicular).
• Medullary rays: Found in between the vascular bundles. They help in radial conduction of substances
• Pith: Abundant and made up of parenchymatous cells in the centre of the stem.