Question

Periderm includes
A) Cork cambium (phellogen), cork (phellem), and secondary cortex (phelloderm)
B) Cork cambium and cork
C) Cork
D) Cork and secondary phloem.

Answer 1

Hint: The meristematic part of the peridermis which consists of one initial layer. Even in the lenticels areas, the cells are organized in sections with virtually no intercellular spaces.

Complete answer:
To solve this question, first we should know about Periderm. Periderm is a protective layer substituting the epidermis as secondary growth displaces, and ultimately destroys, the primary plant body epidermis. This is not found in monocots, and is limited to gymnosperms and eudicots exhibiting secondary development.

Now lets us find the solution from the given options-
A plant’s outer layer is usually called the periderm. It has three components-the cork cambium (phellogen), the cork (phellem) and the phelloderm (secondary cortex). Normally it occurs in case of damage as a result of secondary thickening. So, Cork cambium (phellogen), cork (phellem), and secondary cortex (phelloderm) is the correct answer.
The periderm is generated from the phellogen, a meristematic area that occurs in the epidermis, cortex, phloem, by the dedifferentiation of parenchyma cells. For some but not all plants the phellogen produces phellem to the outside and phelloderm to the inside. So, Cork cambium, and cork cannot be the correct answer. Thus, the option B is the incorrect option.
The periderm is the outermost layer that comprises the cork (phellem), the cork cambium (phellogen) that phelloderm. So, cork cannot be the correct answer. Thus, the option C is the incorrect option.
Cork is the tough protective layer of the plants. The phloem is a translocation responsive vascular tissue. Translocation relates to the process that carries photosynthetic materials to various parts of a vascular plant. So, Cork and secondary phloem cannot be the correct answer.

Thus, the right option is option A i.e. Cork cambium (phellogen), cork (phellem), and secondary cortex (phelloderm).

Note: In woody and many herbaceous dicots, gymnosperms and some monocots, cork cambium is found. Cork cambium is one of the plant's meristem – the collection of tissues composed of embryonic disk cells from which the plant develops.