A bit of my Biology Assignment - Plant Physiology and Anatomy

Hey Everyone,

One of my major assignments at the moment is my Biology assignment on the effects of geotropism and phototropism upon plant shoot erientation. and as part of that I have to do a section of plant physiology and anatomy, and figured I may as well include a bit of it here on my blog, to stop it going stagnant :). So here it is:

With over 275,000 plant species, no one-plant species can be used as a typical example of a plants physiology and anatomy.  All flowering plants, or angiosperms, are either Monocots (monocotyledonae), or Dicots (Dicotyledonae), for classification for monocots and dicots refer Table 1-1 (Starr & Taggart, 1992).

Monocots (monocotyledonae)	Dicots (Dicotyledonae)
One cotyledon (part of embryo in the seed)	Two cotyledon
Flora parts usually occur in threes or multiples thereof	Floral parts usually occur in fours or fivers or multiples thereof
Leaf veins usually are parallel	Leaf veins usually are netlike
Pollen grains basically have one pore or furrow	Pollen grains basically have three pores or furrows
Bundles of vascular tissue distributed throughout ground tissues of stem	Bundles of vascular tissue positioned in a ring in stem
E.g. grasses, lilies, orchids, irises, cattails, and palms	E.g. nearly all familiar trees and shrubs other than gymnosperms, are dicots

Table 1‑1 Differences between monocotyledonae, and dicotyledonae

The root systems (below ground, pertaining to the roots of the plant) and shoot systems (above ground, pertaining to the stems, leaves and flowers) of monocots and dicots are composed of three different varieties of tissues: dermal, ground, and vascular tissues (Starr & Taggart, 1992).

Dermal tissues include the epidermis that covers and protects the surfaces of primary plant parts; and the periderm, that replaces the epidermis on plants showing secondary growth.  Ground tissues can be split into 3 different types.  The parenchyma, generally thin walled, and pertains to the bulk of the fleshy parts of the plants, living parenchyma cells function in photosynthesis, storage, and other tasks.  Collenchyma and sclerenchyma are the two other types, characterized by thickened cell walls, and providing mechanical support for growing plant parts (Starr & Taggart, 1992).

Vascular plant tissues include xylem and phloem.  Xylem contains water-permeable cells that interconnect to form tubes for the conduction and transport of water and dissolved minerals.  Phloem is a food-conducting tissue, containing cells joined end to end, to form pipelines for the transport of sugars and other metabolic products from the leaves.  The cytoplasts of all conterminous living cells are interconnected at cell junctions, or plasmodesmata (Starr & Taggart, 1992).

Plant growth originates at meristems, as summarized in figures 1.1 and 1.2.

Figure 1.1 summary of primary and secondary growth during the development of a stem from a vascular plant (Starr & Taggart, 1992)

Figure 1.2 Summary of primary and secondary growth during the development of a root from a vascular plant (Starr & Taggart, 1992)

“Primary growth, in which roots and shoots elongate, originates at apical meristems, the undifferentiated tissue of self-perpetual cells at root and shoot tips”.  Descendants of some cells of the apical meristem produce the primary tissues.  Lateral meristems (vascular cambium and cork cambium) increase the diameter of stems and roots of plants showing secondary growth.” (Starr & Taggart, 1992)

Stems present photosynthetic tissues, such as leaves, favourable exposure to light, whilst also allowing flowers favourable display for pollinators.  Plant stem’s vascular tissues distribute substances to and from roots, leaves and other plant parts. Dicot stems have vascular bundles arrayed as a cylinder that separates the ground tissue into cortex and pith; whilst monocot stems have vascular bundles distributed throughout the ground tissues.  The photosynthetic parenchyma cells are located between the upper and lower epidermis layer of leaves, whit abundant air spaces surrounding them.  Plentiful openings, or stomata, in the lower epidermal layer allow water vapour and gasses to move across the waxy cuticle (Starr & Taggart, 1992).

Roots act to absorb water and dissolved minerals from the surroundings, and conduct them to aerial plant parts, which could not access the substances otherwise.  The plants also act to anchor and occasionally support the plants, and often offer food storage areas (Starr & Taggart, 1992).

 Well, I'd best get back to work

Happy Gardening,

Michael

p.s. this is just the section at the moment, it's not the final copy, but what do you think thus far?

oh yeah, better include the bibliographic details:

Bibliography

Starr, C., & Taggart, R. (1992). Biology: The Unity and Diversity of Life (6th Edition ed.). Belmont, California, United States of America: Wadsworth Publishing Company.