Read the summary and the most important questions on LooseLeaf for Integrated Principles of Zoology | 9781259562310 | David J Eisenhour, Professor PhD; Susan L. Keen; Larry S Roberts; Cleveland P Hickman, Jr., Emeritus; Helen I'Anson; Allan Larson

• 2 Phenotype plasticity

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• What is phenotypic plasticity?

  The capacity for change within a given genotype to respond to the environmental factors

• What is developmental plasticity?

  Environmental factors during ontogeny determine phenotype of the mature organism

• 3 Lz 3&4

• 3.1 Early concepts: Preformation versus Epigenesis

• What is the preformation concept of development?

  The idea that yound animals were preformed in eggs and that develpment was simply a matter of unfolding what was in the egg.

• What is the epigenesis concept of development?

  This is the idea that a fertilised egg contains building materials only, and these are assembled by an unkown force. Now we know much more about this concept.

• What are the six key events in development?

  1. Gamete formation
     
  2. Fertilisation
  3. Cleavage
  4. Gastrulation
  5. Organogenisis
  6. Growth

• What is meant with "the hierarchy of developmental decisions"?

  The hierarchy in which different cell types arise in conditions created by the stages of development.

• What happend when a structure becomes "determined"?

  As development proceeds the cells go on a course of differentation and their fate in the organism becomes irreversible. This is because of an progressive subdivision.

• What are the two basic processen responsible for the progressive subdivisions in the embryo?

  These are cytoplasmic specification and induction

• 3.3 Cleavage and early development

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• What happens during cleavage in an embryo?

  The embryo divides repeatedly, converting the single cell into many small cells called blastomeres until somatic cell size is attained, no growth occurs.

• When does the embryo enter the blastula stage?

  AT the end of the cleavage stage when the embryo has been divided into many hundreds or thousands of cells