Problem 6 - Biology Concepts and Applications

Question

Epidermis and periderm are________ tissues. a. ground b. vascular c. dermal

Step-by-Step Solution

Answer

Epidermis and periderm are dermal tissues.

Step 1: Understand the Different Tissue Types

First, we need to understand what each type of tissue mentioned in the options refers to. Ground tissues include parenchyma, collenchyma, and sclerenchyma, which mostly provide support and storage. Vascular tissues are responsible for transporting water, nutrients, and food (xylem and phloem). Finally, dermal tissues form the outer protective layer in plants, which include epidermis and periderm.

Step 2: Identify Characteristics of Epidermis and Periderm

Epidermis is the outermost layer of cells in a plant, forming a protective barrier against water loss and infection. Periderm replaces the epidermis in older stems and roots and includes structures like cork. Both are part of the plant's protective layer.

Step 3: Match Epidermis and Periderm to Tissue Types

Given that the epidermis forms the exterior protective layer and the periderm replaces it in certain plant parts, both of these tissues function in protection, which aligns them with dermal tissues in definition.

Step 4: Select the Correct Option

Now that we have established that both the epidermis and periderm are components of the plant's outer protective layers, it is clear they are examples of dermal tissues. Thus, the correct option is 'c. dermal'.

Key Concepts

Epidermis

The epidermis is a very important component of plant biology. It forms the outermost layer of cells that covers the entire plant, including leaves, stems, roots, and flowers. This thin layer functions primarily as a protective barrier. It effectively shields the plant from excessive water loss and acts as a defense against harmful pathogens.

• Composed mainly of tightly packed cells without chloroplasts.
• Functions include retaining moisture and providing a physical barrier against pests.
• Often found covered with a waxy cuticle to further prevent water loss.
• Contains special cells, like guard cells, that help regulate the opening and closing of stomata for gas exchange.

The epidermis is vital for a plant’s survival, as it provides the first line of defense. Its transparency also allows light to penetrate deeper for photosynthesis in green tissues, which is crucial for plant energy production.

Periderm

The periderm replaces the epidermis in older parts of the plant, such as mature stems and roots. As a plant grows, the epidermis often splits from expanding tissues. That's where the periderm comes in as a more robust layer of protection.

• Composed of cork cells, phelloderm, and cork cambium.
• Cork cells are dead at maturity and have a substance called suberin that makes them highly impermeable and protective.
• This layer helps reduce water loss and insulates the plant against temperature fluctuations.
• Typically responsible for giving bark its texture and color.

The periderm is crucial for the evolving needs of a plant's structure, especially as it accumulates girth and age.

Dermal Tissue

Dermal tissue constitutes the complex protective covering of plants, encapsulating both the epidermis and periderm. As dermal tissues, they provide a shield against environmental stressors and help in maintaining internal stability.

• Initially, the epidermis forms the primary dermal tissue covering younger plant parts.
• With maturity, the periderm takes over in specific areas, enhancing protective capabilities.
• The structure and function adapt in response to environmental factors and growth demands.
• Both layers are crucial for preventing mechanical injury and defending against pathogens.

Through these adaptive features, dermal tissue ensures that plants can thrive in various environments and conditions, highlighting its role as an integral part of plant survival.