HL 1 Biology

5.4b Natural Selection

• AA-CC: 197-9

<<Natural Selection>>

  • Charles Darwin: developed theory of natural selection
  • took voyage around the world on HMS Beagle
  • The Origin of Species: book he wrote explaining theory + evidence of natural selection
    • overpopulation -> struggle for some individuals to survive, some go extinct 
    • Adaption (variation) -> better adapted wil tend to survive than less well-adapted (natural selection)
    • Variation Heritable -> better adapted reproduce/pass characteristics to offsprings + characteristics of population gradually change(evolution)

<<Responses to Darwin’s Theory>>

  • Linked concepts in Darwin’s theory of evolution: 
    • population growth
    • resource limitation
    • a struggle for existence
    • variation
    • adaption
    • differential reproduction
    • natural selection
    • descent with modification
    • origin of species
    • extinction of species
  • theory is strengthened by research, such as sexual reproduction promoting variation in species, but not enough proof to state that it is “true” 


Missing Links (p.196)

1) Length of Dilong paradoxus:  (110 mm/7mm) x 100 = 15471 mm

2) 3 similarities between Dilong paradoxus  vs. reptiles that live on Earth today: bones of skull, vestigial organs (teeth), tail vertebrae

3) A function for the protofeathers of Dilong paradoxus could have been to provide insulation as it could control the body temperature at a stable level. 

4) Two features which Dilong paradoxus would have had to evolve/to become capable of flight includes the reduction of the body size as well as the development of wings/limbs. 

5) It is not possible to be certain whether the protofeathers of Dilong paradoxus are homologous with the feathers of birds because theses organisms cannot be directly observed nor is there DNA evidence to support this statement. 


One thought on “5.4b Natural Selection

  1. Grade 7 A consistent and thorough understanding of the required knowledge and skills, and the ability to apply them almost faultlessly in a wide variety of situations.

    Data-based questions: missing links
    page 196
    1 1600 mm/ 1.6 m
    2 Answer should refer to:
    • Similar skull bones.
    • Similar dentition.
    • Similar tail vertebrae.
    3 Maintenance of a stable body temperature/
    4 Modified forelimbs; smaller body size.
    5 Direct observation not possible; DNA/molecular
    evidence not available.

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