BIO 104 4/5/96

Review:
     Alternation of Generations:

-Sporic meiosis:  the end result is the production of spores. Characteristic of Plant life cycle

-Sporophyte (2n):  Sporangia posses spore mother cells which go through meiosis and produce
spores.  The spores give rise to the gametophyte.

               1) Antheridia give rise to sperm
               2) Archegonia gives rise to the egg

-Syngamy is the union of the sperm and the egg. This process is called alternation of generations
because you alternate between haploid and diploid cells.

Refer to Figure 28.7 page 532   The life cycle of a heterosperous vascular plant.

Homologies between chlorphyta and land plants:
     1) Same type of chlorophyll (A & B) and accessory pigments 
     (Beta Carotene)
     2) Starch is stored in plastids.  Green algae gave rise to land plants.
     3) Cell walls of cellulose
     4) Most green algae live in fresh water


Phylogenetic Tree
     Bryophytes               Ferns1    Gymnosperms2   Angiosperms3
 (Mosses and Liverworts)
                                 ^               ^     ^    
             ^                     ^              ^   ^
               ^                     ^            Seed Plants
               ^                      ^           approx. 375 MYA
                   ^                           ^
                     ^                  ^        ^
                       ^           Conductive Tissue
                         ^         approx. 400 MYA
                           ^
                             ^         ^
                              Land Plants
                                   ^ 
                              Green^Algae
1  No seeds
2  190 MYA
3  135 MYA

Adaptations to Life on Land

Problem:                           Solution:
1)  Excessive water loss by        Development of waxy cuticle on
     evaporation.                  the surface of above ground   
                                   parts.

2)  Obtaining gases for            Development of stoma (hole) and 
     photosynthesis.               guard cells.  These guard cells 
                              regulate the loss of water vs. the obtaining of                                 gases.

3)  Obtaining and transporting          Root to anchor and obtain water.
     water to the cells of the          Xylem tissue to move water
     plant.                        throughout the plant.
                                   
4)  Transport of photosynthesis         Development of phloem tissue.
     product to other plant        Movement of sugar and other 
     parts.  Ex. roots             organic molecules.

5)  Support the plant body              Development of specialized against the pull of                             gravity. Xylem in higher plants.

6)  Reproduction outside of a      Pollen (pollen tube grows and sperm nucleus
    watery environment.            fertilizes the egg).
                              -Seed coat encases the embryo.

Classification of Plants
 

A. Non vascular (Bryophytes -mosses, liverworts, hornworts   

B. Vascular
     I.  Seedless (Ferns, horsetails, whisk ferns)

     II. Seeds
          a.  Gymnosperms (conifers, cycads, Ginkgo, etc.)
          b.  Angiosperms
               1. Dicots (seed can break into 2 cotyledons)
                    -oak
                    -roses
                    -cacti
                    -sunflowers



               2. Monocots (only one cotyledon)
                    -palms
                    -grasses
                    -orchids
                    -lilies

Dicots have Netted Veins      Monocots have parallel venation
Ex. Maple Leaf                     Ex. blade of grass