EVOLUTION QUESTION 1991:			    L. PETERSON/AP BIOLOGY

	Discuss how each of the following has contributed to the evolutionary 
	success of the organisms in which they are found.

		a.  Seeds
		b.  Mammalian placenta
		c.  Diploidy

 
  STANDARDS:
  
  SEEDS:       (Max of 4 points) 
  
  __PROTECTION:  from drying, infection, mechanical injury (tough coat)
  __FOOD:  Source: cotyledons, endosperm. Result: more pre-germination 
        (embryonic) development, i.e. radicle, hypocotyl, epicotyl, etc.
  __DISPERSAL:  examples include fruit, hooks, animals, wind, water, etc.
  __DORMANCY:  timing of germination increases competitive success 
                 (possible reduction in overcrowding)
  __ADAPTATION:  to or Colonization of new land environments
  __OPTIONS FOR VARIATION IN NUMBER of seeds vs. parental investment
  __HORMONE production/internal regulation
  
  PLACENTA:    (Max of 4 points)
  
  __EXCHANGES of food & O2 and/or waste or CO2 (description of placental structures)
  __HOMEOSTATIC environment (stable/temperature or chemicals; amniotic fluid)
  __IMMUNITY (antibodies cross placenta)
  __PREDATION reduced
  __MORE DEVELOPED organism at time of birth (retained longer)
  __SURVIVAL CHANCES increased, therfore fewer offspring needed
  __MOBILITY and independence of parents during fetal development
  __DEVELOPMENTAL SIGNALS:  hormone regulation/communication via mother-fetus 
        connection
  
  DIPLOIDY:    (Max of 4 points)
  __VARIATION through fertilization/syngamy/two parents
  __VARIATION through meiosis/crossing over/recombination/
         independent assortment/segregation
  __MODES OF INHERITANCE:  co-dominance, polyploidy
  __RESULT OF VARIATION is potential for adaptation
  __MASKS MUTATION or hides variability/heterozygosity/recessive alleles retained 
         in gene pool
  __HYBRID VIGOR provides certain advantages
  __BACK-UP set of chromosomes for gene replacement/repair/conversion
  __LIFE CYCLES/alternation of generations
  
  OVERVIEW:    (1 point)
  __DEFINITION of evolutionary success in terms of survival of fittest or natural 
        selection