Lec # 2. Review: Plant Body- form & function        Slides

Seed plants have developed appropriate structures to carry out the functions needed for growth, survival, and reproduction on dry land.

Adaptations include structures to prevent drying out, to exchange gases, to conduct water and nutrients long distances, to support the plant body, and to carry out sexual reproduction.

1. A plant body is made up of cells, tissues and organs. 

a.  ORGANS:

Veg. body is made up of three organs:

LEAF,

STEM

ROOT

Reproductive organs are:

FLOWER

FRUIT

b.  TISSUES: Each organ is made of several tissues.

1. DERMAL

2. GROUND

3. VASCULAR

4.  MERISTEM

c.  CELL TYPES: One or more cell types make a tissue.

e.g. dermal tissue includes the epidermis, guard cell (leaf)

Ground tissue: includes cortex, mesophyll parenchyma

Vascular tissue includes xylem tracheids,phloem sieve tube, companion cells

Cells are grouped in tissues and several tissues make up an organ.

The ability of plants to grow and develop depends on the ability of individual cells to divide, differentiate and to carry out their intended functions.

2.  How do plants develop into these organs, tissues and cell-types?  Plant development is characterized by permanent embryogeny (in contrast to animals).

Development includes

•              cell division in the meristem
• `            enlargement (cell elongation) and
•              differentiation or specialization

-Meristem:

a. Apical root meristem --> root
b.  Apical shoot meristem (Apical in dicots)  --> stem and leaves
     [Monocots- cereals and grasses: intercalary meristem]
c.  Lateral (Secondary) meristem develop from mature cells later in development:

-vascular cambium increase diameter of stem, gives rise to xylem and phloem

-cork cambium

3.  A cell is the fundamental unit of life. Life does not exist in units smaller than cells. Cells arise only from the division of of preexisting cells. [Cell Theory]

4.  Why do cell types differ in shape and sizes and in their functions? Cell shape and function are determined in large part by the regulation of genes expressed and the regulation of protein activities.  These are dependent on  environmental factors, hormones and on the developmental program.
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Review Questions:
1.  What is the relationship between cells, tissues and organs?
2.  What are the dermal, ground and vascular tissues of a root?
    Draw a longitudinal section of a root and label the respective tissues.
    What are meristem cells, and where are they found in the root?
3.  Name at least one cell type within each of the tissues  in # 2.
4.  What is the major function of  xylem?  phloem?
 

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