Botany/Plant structure discussion

Further Discussion

The questions posed in Chapter 3. Plant Structure are discussed further on this page. Remember, some questions are intended to be thought-provoking and more than one answer may be "correct".

Question:

• At this point the conceptual differences between cell types, tissues, organs, and organisms may be somewhat confusing. Using the leaf as an example, describe this structure in a way that considers the cell types, tissues, and organs for that part of the leaf where photosynthesis is concentrated.

Photosynthesis is concentrated in the mesophyll of the leaf. The mesophyll is a type of tissue composed of two layers or arrangements of chlorenchyma cells: an upper pallisade layer of tightly packed parenchyma (called pallisade chlorenchyma), and a lower spongy layer of loosely packed parenchyma (or spongy chlorenchyma). One could regard these layers as different tissue types (simple tissues) and the mesophyll as a complex tissue. The mesophyll is packed between two protective layers of epidermal cells (tissue: epidermis of epidermal cells and cuticle), which along with the vascular tissue and perhaps other structural tissues form an organ called the leaf whose primary function is food production for the organsim: the plant.

Leaves usually have a stem-like structural part called a petiole by which they attach to another plant organ termed the stem.

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