Question

The epidermis is generally covered with a waxy thick layer called the which prevents the loss of water. (a) Suberin (b) Tunicin (c) Cuticle (d) Chitin

Short answer

The correct answer is (c) Cuticle. The cuticle serves as the waxy, water-repelling layer on the epidermis of leaves and other parts of plants.

Step-by-step solution

Understand the Role of Epidermis Layer

Recognise the role of the epidermis layer in preventing water loss. It is typically covered by a waxy thick layer which serves this function.

Evaluate the Provided Options

Investigate each option to understand its characteristics and correlate with the property described in the question. Here are the basics about each option, (a) Suberin: a waxy substance found in plants, typically in cork cells. (b) Tunicin: a form of cellulose found in tunicates or 'sea squirts'. (c) Cuticle: a protective film covering the epidermis of leaves, young shoots and other aerial plant organs. It consists of lipid and hydrocarbon polymers impregnated with wax, and is synthesized exclusively by the epidermal cells. (d) Chitin: a long-chain polymer of N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world, including the exoskeletons of arthropods, such as crustaceans and insects, and the cell walls of fungi.

Determine the Correct Answer

From the brief descriptions of each option, it is evident that ‘Cuticle’ (Option C) is the most suitable answer as it is described as a wax like protective covering found on leaves, young shoots, and other aerial plant organs. The purpose of the cuticle is to prevent water loss within the plant and therefore is the most suitable answer to the question.

Key concepts

Cuticle

The cuticle in plants is a fascinating structure. This thin but vital layer forms on the epidermal surface, which is essentially the plant's outer skin. The cuticle consists mainly of cutin, a waxy, water-repellent substance, but it can also include various waxes and fatty acids. This composition enables the cuticle to act as a barrier, shielding the plant from various environmental hazards.

• The cuticle serves as the primary shield against harmful pathogens.
• It also plays a significant role in controlling the water absorption and loss through the plant's surface.
• Not only does it preserve moisture, but it also prevents excessive water intake during rainy periods.

The cuticle's efficiency is crucial for the plant's survival, particularly in dry or harsh climates. By minimizing water loss and providing a formidable defense, the cuticle helps plants maintain their internal water balance and ward off potential dangers.

Water Loss Prevention

Water is essential for plant life, yet too much loss can be detrimental. Plants have evolved to minimize this through various features and strategies; among the most important is the cuticle. The cuticle acts as a water-tight sealant over plant surfaces, primarily on leaves. This prevents water from escaping unnecessarily, ensuring the plant retains vital moisture within its cells and tissues.

• The thickness of the cuticle can vary based on the plant's habitat, being thicker in dry areas to provide extra water retention.
• Plants have stomata—small openings regulated by guard cells—further balancing water retention by opening and closing based on environmental conditions.
• This precise control is essential to prevent dehydration or wilting, enabling steady growth and reproduction.

Together, these adaptations form an effective mechanism which ensures that plants thrive in diverse environments by managing water carefully.

Plant Protective Layers

Plants have developed a variety of protective layers to guard against external stressors, and the role of these layers is crucial for their survival. The epidermis is the primary protective layer, often adorned with the cuticle, which we previously discussed as a waxy outermost surface. However, there are other components contributing to this protective function.

• The epidermis itself acts as a first line of defense, providing a physical barrier against invading organisms.
• The presence of trichomes—tiny hair-like projections—on the epidermis helps deter herbivores and reduce transpiration.
• In addition to physical barriers, plant epidermal layers help facilitate the secretion of important compounds that deter pests and pathogens.

These structures work hand-in-hand to give plants a resilient exterior, reducing damage from environmental threats and ensuring that their photosynthetic processes continue unimpeded.