1.7.3 Homologous Structures

Question 1

homologous structures

Answer 1

• equivalent structures between species with common
  ancestors. Homologous structures may or may not look alike or perform the same function.
• The bones found in the arms of humans, whale flippers, cat legs, and bat wings are arranged similarly
• Genes determine structure. If characteristics of different species result from common ancestry, then the species will have similar genes.

Question 2

analogous structures

Answer 2

• between species can have superficial and functional similarities, not because of common ancestry, but because of convergent evolution
• The wings of bats, birds, and moths

Question 3

convergent evolution

Answer 3

• takes place when structures with similar functions arise separately in different species.
• These structures are similar in function but did
  not arise from common ancestry. Each of these structures evolved separately in a process

Question 4

embryos

Answer 4

• The embryos of distantly related members of
  the animal kingdom appear similar even though as adults, the species look quite different. The species share homologous structures, such as vestigial gills, tails, and general morphology.
• These homologous structures in embryos indicate a common ancestry.

Question 5

If a trait called segmentation arose before arthropods and annelids (worms) branched out from each other, its presence in both groups is the result of

Answer 5

• homology

Question 6

What is the mechanism by which homologous structures arise?

Answer 6

• Genetic inheritance determines homologous structure

Question 7

The ostrich and emu look very similar and live in similar environments but are not closely related. This is an example of

Answer 7

• analogous structures.

- convergent evolution.

Question 8

The bones of the human forearm are homologous in structure to all of the following except

Answer 8

• a butterfly wing

Question 9

In ________________, organisms with different ancestors become similar because they share the same environment. Structures that have similar form and function between these organisms are called ___________ structures.

Answer 9

• convergence, analogous