Which cell type is only in secondary tissue?
Cuticle
Collenchyma
Periderm cork cells
Epidermis
Sclerids
Periderm cork cells.
Periderm cork cells are the cell type that is only found in secondary tissue.
The cell type that is only found in secondary tissues is the periderm cork cells. To understand this, let's break it down:
1. Cuticle: The cuticle is a waxy layer that covers the epidermis of leaves, stems, and other aerial plant organs. It is formed by the epidermal cells, so it is not unique to secondary tissues.
2. Collenchyma: Collenchyma cells are elongated plant cells that provide support to growing regions of the plant. They can be found in both primary and secondary tissues, so they are not exclusive to secondary tissues.
3. Periderm cork cells: Periderm cork cells, also known as phellem cells, are specific to the secondary tissues of plants. They are part of the protective layer that replaces the epidermis in stems and roots as the plant grows older. These cells are dead at maturity and have walls impregnated with suberin, a waterproof material.
4. Epidermis: The epidermis is the outermost layer of cells in plants. It consists of closely packed cells that provide protection against physical damage and water loss. The epidermis can be found in both primary and secondary tissues.
5. Sclerids: Sclerids are a type of sclerenchyma cell that provides additional structural support to the plant. They are hard, non-living cells with thick cell walls. Sclerids can be found in both primary and secondary tissues, so they are not exclusive to secondary tissues.
In summary, the periderm cork cells are the only cell type listed that is exclusively found in secondary tissues.