The correct option is
A: "Has a very thin cuticle."
Detailed Explanation
- Understanding the Piliferous Layer:
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The piliferous layer, also known as the epidermis of the root, is the outermost layer of cells in the root structure. Its primary function is to protect the underlying tissues and facilitate the absorption of water and nutrients from the soil.
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Analyzing Option A:
- Statement: "Has a very thin cuticle."
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Truth: This statement is NOT true. The piliferous layer typically has little to no cuticle. A cuticle is a waxy layer that helps prevent water loss, but in roots, the absence of a significant cuticle is advantageous for absorption. Roots need to absorb water and nutrients efficiently, and a thick cuticle would hinder this process.
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Analyzing Other Options:
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Option B: "Is the outermost layer of the cortex."
- Truth: This statement is true. The piliferous layer is indeed the outermost layer of the root cortex. It serves as the first line of defense and plays a crucial role in the absorption of water and minerals.
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Option C: "May bear root hairs."
- Truth: This statement is also true. The piliferous layer can develop root hairs, which are extensions of the epidermal cells. These root hairs significantly increase the surface area for absorption, allowing the plant to take up more water and nutrients from the soil.
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Option D: "Breaks down as the root ages."
- Truth: This statement is true as well. As roots mature, the piliferous layer can degrade or slough off, especially in older roots. This process allows for the development of new root hairs and the replacement of older, less efficient cells.
Summary of Why Other Options Are Correct:
- B is correct because the piliferous layer is indeed the outermost layer of the cortex.
- C is correct because root hairs are extensions of the cells in the piliferous layer, enhancing absorption.
- D is correct because the piliferous layer can break down as the root ages, allowing for new growth and adaptation.
Common Pitfalls:
- Students may confuse the piliferous layer with other layers of the root, such as the cortex or endodermis, which have different functions and structures.
- Misunderstanding the role of the cuticle in roots versus leaves can lead to incorrect assumptions about the presence of a cuticle in the piliferous layer.
Revision Summary:
- The piliferous layer is the outermost layer of the root cortex and is crucial for absorption.
- It typically has little to no cuticle, facilitating water and nutrient uptake.
- Root hairs, which increase surface area for absorption, are found on this layer.
- The piliferous layer can break down as the root matures, allowing for new growth.