Problem 188 - Objective Biology for NEET

Question

Assertion: Thick cuticle is mostly present in disease resistant plants. Reason: Disease causing agents cannot grow on cuticle and cannot invade the cuticle.

Step-by-Step Solution

Answer

The reason accurately explains the assertion, therefore both the assertion and the reason are correct, and the reason is the correct explanation for the assertion.

Step 1: Understand The Assertion

The assertion claims that a thick cuticle is mostly present in disease resistant plants. This is based on the fact that plants with a thick cuticle can better shield themselves from diseases.

Step 2: Understand The Reason

The reason provided is that disease-causing agents cannot grow on the cuticle and cannot invade it. This statement elaborates on the function of the cuticle in preventing the growth and invasion of disease-causing agents.

Step 3: Determine The Relationship

Connect the assertion and the reason. Analyze if the reason accurately elucidates the assertion or not. In this case, it does; the reason suitably explains why a thick cuticle on the plant can lead to disease resistance, making the plants less vulnerable to external infections.

Key Concepts

Thick Cuticle in Plants

The epidermis of a plant is like its skin, and just as human skin is protected by a layer of dead cells, the plant epidermis has a protective layer known as the cuticle. A thick cuticle functions as a sturdy barrier, safeguarding plants from environmental stresses, including disease-causing agents.

This adaptive feature is particularly prevalent among disease-resistant plants. It acts much like a high wall around a fortress; the thicker the wall, the harder it is for invaders to breach it. In ecological settings where pathogens are rampant, possessing a thick cuticle can be a crucial characteristic for a plant's survival.

Increasing a plant's cuticle thickness can be seen as fortifying its defenses, making it less susceptible to pathogens that depend on accessing the internal tissues to cause harm. By understanding the importance of a thick cuticle, agricultural practices can be directed towards breeding or engineering plants to foster this trait, enhancing crop resilience.

Disease Causing Agents in Plants

Pathogens that threaten plant health are diverse and numerous. They include bacteria, fungi, viruses, and even nematodes. Each of these disease-causing agents can invade plant tissues in different ways and cause a variety of symptoms, from leaf spots and wilting to systemic infections that can be lethal.

Bacteria and fungi are notorious for infiltrating through plant stomata or wounds in the plant tissue, whereas viruses often rely on vector organisms, such as insects, to penetrate plant cells. Nematodes, on the other hand, directly penetrate root cells. The plant's cuticle provides the initial line of defense against these agents.

Understanding the mechanisms by which these pathogens attack plants is crucial for developing effective disease management strategies. This knowledge helps in the creation of resistant plant varieties and in the application of targeted treatments that can address the specific vulnerabilities of plants to these disease agents.

Plant Cuticle Function

The plant cuticle serves multiple essential functions. At its core, it acts as a protective barrier, but its roles extend into various aspects of plant life, including water retention, defense against pests, and stress tolerance.

Water conservation is a key function of the cuticle since it minimizes water loss through transpiration by providing a hydrophobic layer. This feature is especially vital for plants in arid climates. Beyond water regulation, the cuticle is imbued with waxes that can deter herbivorous insects and mitigate the impact of harmful UV radiation.

Investigations into the chemical properties of the cuticle have revealed that it can also play a role in communication, utilizing secreted chemicals to signal distress or to attract beneficial organisms. These multifaceted functions make the cuticle a critical component in plant health and resilience. By strengthening the cuticle, plants gain a better chance to thrive in their ecosystems, which ultimately contributes to higher yields and more sustainable agriculture.