Tag: epidermal tissue system

A lenticel is mainly the opening present on the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It is a porous tissue consisting of cells with large intercellular spaces. It helps in the direct exchange of gasses between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gasses. Lenticels are found in most of the woody trees but absent is  woody climbers. If lenticels are blocked then root will die first due to lack of gaseous exchange. Thus, option C is correct.

A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in vascular tissue, which exists in two forms: xylem and phloem. These are generally present in the veins of the leaf where the xylem channelizes the water and phloem conducts the prepared food from the source to the sink.

Bulliform cells  are so called because of its peculiar bubble shape. It mainly occurs on the upper surface of the leaves present in grasses. Water present in these cells helps to maintain its shape but loss of turgor pressure during the stress allows the leaves to roll up. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. Bulliform cells are present in only monocot leaf and absent in dicot leaf. 
Thus, the correct answer is option A.

Laticiferous vessels are the specialized thin walled parenchymatous cells that secrete latex and are found in the cortex. They lack pits and are composed of cellulose and hemicelluloses and serve to secrete latex. 

Vascular bundles of the plant show vascular cambium or cork cambium. Cork cambium is involved in making cork. Cork is a nonliving, water resistant tissue formed in many plants to prevent water loss. Cork cells are dead and have cell walls composed of a waxy substance "suberin" which is highly impermeable to gasses and water. This substance prevents the water loss from the stem. Cork also protects the plant from wear and tear. Hence, it is a protective type of tissue. Therefore, option A is correct.  

The epidermis is the outermost cellular layer which covers the whole plant structure, i.e. it covers roots, stem, leaves, flowers, and fruit. It is composed of a single layer of living cells. The outer walls, which are exposed to the atmosphere and usually thickened, are covered by a waxy, waterproof cuticle which is made up of cutin. The waxy cuticle prevents the loss of moisture from the leaves and stems. During drought, the plant hormone abscisic acid (ABA) triggers stomatal closure, thus reducing water loss.

In some higher plants, the cuticle is a water-impervious protective layer covering the epidermal cells of leaves and other parts and limiting water loss. It consists of cutin, a waxy, water-repellent substance allied to suberin, which is found in the cell walls of corky tissue. Cutin is especially noticeable on many fruits—e.g., apple, nectarine, and cherry, which can be buffed to a high gloss. 

A root hair, or absorbent hair, the rhizoid of a vascular plant, is a tubular outgrowth of a trichoblast, a hair-forming cell on the epidermis of a plant root. In root epidermis, epidermal hairs, termed root hairs are common and are specialized for absorption of water and mineral nutrients. In plants with secondary growth, the epidermis of roots and stems is usually replaced by a periderm through the action of a cork cambium. 

Trichomes or hairs grow out from the epidermis in many species. In root epidermis, epidermal hairs, termed root hairs are common and are specialized for absorption of water and mineral nutrients. Guard Cells are the only epidermal cells that can make sugar. As a result, water from other cells enter the guard cells by osmosis so they swell and become turgid. 

Epidermis is a single layer of cells found on outer layers in different parts of a plant, viz., leaves, flowers, roots, stem, etc.  Its functions are as follows,