PLANT REPRODUCTION QUESTION 1982			L. PETERSON/AP BIOLOGY
	In the life cycle of a fern and a flowering plant, compare and contrast each
	of the following:
		A.  The gametophyte generation
		B.  Sperm transport and fertilization
		C.  Embryo protection

 
  STANDARDS:
     A maximum of 10 points was allotted to each of the fern portion and the 
     angiosperm portion of the question. This meant that a student had to include
     correct information on each group of plants in order to achieve a score of 15.
     Within this limit, a single point was given for each valid idea presented. A
     score of more than 15 received a 15. The following outline indicates possible
     responses for which points were awarded.
  
  A.  GAMETOPHYTE GENERATION
     FERN
  __ Haploid
  __ Reduced in comparison to sporophyte
  __ Characterized as a heart-shaped prothallus
  __ Eggs formed in archegonia
  __ Sperm formed in antheridia
  __ Details of archegonial structure
  __ Details of antheridial structure
  __ Gametophyte is photosynthetic; has rhizoids for anchoring and water absorption
  
     FLOWERING PLANT
  __ Male (micro)gametophyte (or pollen grain is immature microgametophyte)
  __ Female (mega)gametophyte or embryo sac
  __ Structure of microgametophyte normally two cells, a tube and a generative cell 
                 (sometimes identified as a tube cell and two sperm nuclei)
  __ Structure of megagametophyte is 7 cells with 8 nuclei
  __ Both gametophytes nutritionally dependent on the sporophyte
  __ Haploid
  __ Gametophyte develops usually from one type of spore in ferns (homospory), 
        while in the flowering plnats each gametophyte develops from a different type 
        of spore (heterospory).
  
  B.  SPERM TRANSPORT AND FERTILIZATION
     FERN
  __ Swim to archegonium and require dew, moisture, etc., for transport
  __ The neck canal cells and ventral canal cell of the archegonium disintegrate
  __ Disintegration of cells may form a chemical that attracts sperm
  __ Fertilization occurs in venter of the archegonium
  
     FLOWERING PLANT
  __ Pollen transport from anther to stigma of the pistil
  __ Pollination agent (example)
  __ Pollen grain germinates and grows through the style
  __ Pollen tube penetrates the ovule (usually through the micropyle)
  __ Double fertilization occurs (is characteristic of the angiosperms)
  __ Details of double fertilization
  
     C.  EMBRYO PROTECTION
  FERN
  __ Embryo develops in center of archegonium
  __ Embryo is surrounded by and protected by cells of the archegonium
  __ Embryo dependent upon gametophyte for nutrition until the third or 
        fourth leaf forms
  __ Gametophyte ultimately dies
  
     FLOWERING PLANT
  __ Embryo protected within a seed (which forms from the ovule)
  __ Integuments of ovule become a hardened seed coat
  __ Nucellus of the ovule withers and dies
  __ Endosperm provides nutrition for the developing embryo
  __ The seed is enclosed within a fruit which develops from the ovary wall 
        and sometimes includes accessory tissue of the flower.
  __ Ovary wall forms the pericarp of the mature fruit
  __ Pericarp has three layers: endocarp, mesocarp, and exocarp