89. HOMOLOGY

Question 1

1. Define Homology.

Answer 1

• it is the similarity between species
• this results from a common ancestry

Question 2

2. What are the 2 types of Homology?

Answer 2

1. Anatomical Homologies
2. Molecular Homologies

Question 3

3. What are Anatomical Homologies?

Answer 3

• these are similarities in Anatomical Features
• these features are known as Homologous Structures

Question 4

4. What are Molecular Homologies?

Answer 4

• these are similarities in genetic material

Question 5

5. What is the Molecular Homology percentage between Human Chromosomes and Chimpanzee Chromosomes?

Answer 5

• 99%

Question 6

6. What is the Molecular Homology percentage between Human Genetic Material and Mouse Genetic Material?

Answer 6

• 95%

Question 7

7. Define Homologous Structures.

Answer 7

• these are anatomical similarities
• they represent the variations on a structure that was
  present in a common ancestor

Question 8

8. Define Comparative Embryology.

Answer 8

• this reveals anatomical homologies
• these are not visible in adult organisms

Question 9

9. What is an example of a Molecular Homology?

Answer 9

• the genes shared among organisms
• these genes were inherited from a common ancestor

Question 10

10. What is an example of an Anatomical Homology?

Answer 10

• Vestigial features
• these are specific anatomical structures within an
  organism
• these structures have lost all or most of their original
  function
• this happened throughout the course of evolution

Question 11

11. How are Vestigial Structures important?

Answer 11

• they are the remnants of features
• these features once served important functions in the
  organism’s ancestors

Question 12

12. What is an example of a Vestigial structure?

Answer 12

• the Human Appendix

Question 13

13. What is a Human evolution example that revolves around Anatomical Homology?

Answer 13

• the progression from a fully functional cecum
• to the current human appendix

Question 14

14. What is the Appendix?

Answer 14

• this is a dead-end pouch
• it forms a part of the large intestine

Question 15

15. According to Darwin, what was the purpose of the Appendix for ancestral organisms?

Answer 15

• Herbivores used it to digest leaves

HERBIVOROUS ANIMALS:
- have a very long cecum
- this hosts the bacteria that is needed to digest
cellulose

Question 16

16. What happened after human ancestors began to eat more easily digested foods?

Answer 16

• humans became less reliant on cellulose-rich plants
• the cecum became less necessary

MUTATIONS STARTED TO ACCUMULATE IN THE HUMAN POPULATION:
- these mutations included individuals with a small
cecum size
- the cecum continued to shrink through the
generations

Question 17

17. What result did Evolution have on the Cecum?

Answer 17

• the cecum degraded to be the current Appendix

Question 18

18. What are Mammalian Forelimbs an example of?

Answer 18

• Homologous Structures
• this ties in with Anatomical Homology

Question 19

19. What are Vertebra Embryos an example of?

Answer 19

• Homologous Structures
• this ties in with Anatomical Homology

Question 20

20. What are Evolutionary Trees?

Answer 20

• they are hypotheses about the relationships between
  different groups

Question 21

21. What relation do Homologies and Evolutionary Trees have?

Answer 21

• the homologies form distinct patterns in Evolutionary
  Trees

Question 22

22. What are Evolutionary Trees composed of?

Answer 22

• they can be made using different types of data

EXAMPLE:
- anatomical data
- DNA sequence Data
- this is known as a Phylogenetic Analysis