EVOLUTION QUESTION 1995:		L. PETERSON/AP BIOLOGY

	The problems of survival of animals on land are very different from those of survivial
 	of animals in an aquatic environment. Describe four problems associated with animal
 	survival in terrestrial environments but not in aquatic environments. For each problem,
 	explain an evolutionary solution.

  
  3 points maximum per problem
     1 point for a description of a problem, or a comparison of a problem between water 
          and land environments
     1 point for an explanation of a solution clearly linked to an appropriate problem
     1 point for an elaboration of a problem, or a solution description, or an additional solution
  
  Problem and Examples of Descriptions               Examples of Solutions (including but not limited
  to)
  Does not require description   (description inherent in words of problems)
  
  __Water Acquisition                   drinking, "metabolic water", absorption, etc.
  
  __Water Conservation/Retention        kidney differences (i.e., Loop of Henle), ADH, 
                              storage, behavioral adaptations (i.e., nocturnal,
                              estivation, burrowing), etc.
  __Desiccation of Body Surfaces        scales, feathers, mucus, cutin, exoskeletons,
                              keratinized skin, etc. 
  __Desiccation of Respiratory Surfaces      invagination of gas exchange surfaces, moist
                              mucus membranes, etc.
  __Desiccation of Embryos              shelled (amniote) egg, calcareous shell of birds,
                              ovovivipary, vivipary, invertebrate egg sacs, 
                              internal development, etc.
  __Desiccation of Gametes              internal fertilization, seminal/vaginal fluids, etc.
  
  Requires description
  __Sperm Transport                internal fertilization, seminal/vaginal fluids, etc.
        (due to lack of fluid medium)
  __Excretion / Electrolytes / Water         liver/kidney adaptations, skin excretion, large 
        (due to more extreme conditions on land)  intestine absorption, salt glands, excrete urea 
                              and uric acid, behavioral adaptations, etc.
  __ Body Support                  reinforced or hydrostatic skeletons, muscular 
         (difference in net gravity effect)       walls, appendages, etc.   
  __Food Acquisition                    specialized nervous and sensory systems, legs,
        (due to absence of "filter feeding")      claws, behavioral adaptations, etc.
  __Temperature Fluctuations            physiological adaptations (sweating, shivering, 
        (without water's modifying effect)        cardiovascular adaptations, endothermy), 
                              behavioral adaptations, morphological 
                              adaptations; counter-current principle, etc.
  __Radiation (ultraviolet)             pigmentation, body covering, behavioral          
        (due to damage to nucleic acids, cells,   adaptations, repair enzymes, etc.
         reduced immune function, etc.)
  __Sensory Differences            balance, sound reception, stereoscopic
        (due to lower density of air)             vision, ear, etc.
  
  
  
  
  
  
  
  Overall Commentary for Question:
  
     This question asked the students to understand the differences between aquatic and
  terrestrial environments and the stresses put on animals on land that were not present in the
  water. Four problems associated with animal's success on land needed to be described and an
  evolutionary solution to each problem needed to be explained and linked to the problem.
  
     Standards were established to ensure that the problems encountered by terrestrial
  animals were different from those encountered by aquatic animals. Thirteen problems were
  established . Each problem described had to have an evolutionary solution. Students needed to
  demonstrate clear understanding of both the problem and the solution.