Questions and Answers
What is a vestigial structure? List an example of a vestigial structure.
Vestigial structures are reduced structures that trace homologous structures in other species. Examples include the human tailbone and the human appendix.
What is the best way to determine if two species are closely related?
The best way is to compare the DNA of the two species.
If you observed the bones in a dolphin's flippers and the bones in a human hand, what is this an example of?
This is an example of homologous structures.
What are analogous structures? List an example of analogous structures in two different species.
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Where would a scientist likely find a fossil?
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List the 3 types of evidence for evolution.
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How do vestigial structures add to the evidence of evolution?
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Where are the oldest fossils found in sedimentary rock? Where are the youngest fossils found?
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What causes sedimentary rock?
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Why are most fossils found in areas that once were covered with water?
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Why might a scientist find fossils in different layers of rock that are similar but not exact copies of each other?
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Why do some whales have a pelvic bone although they have no legs?
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Would two organisms on a cladogram that are far apart have more or less amino acids in common?
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What is a cladogram? What can a cladogram tell us?
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What is an index fossil?
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If 2 organisms have many of the same amino acid sequences, they would be __________ related to each other.
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If 2 organisms do not have many of the same amino acid sequences, they would be __________ related to each other.
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What can the amino acid sequences between two organisms tell us?
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What does the fact that all organisms have DNA tell us about a common ancestor?
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What is comparative embryology and what does this tell us about evolution?
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Study Notes
Vestigial Structures
- Vestigial structures are reduced traces of homologous structures found in related species.
- Examples include the human tailbone, certain bones in whales, and the human appendix.
Determining Relationships Between Species
- DNA comparison is the most effective method to determine the relatedness of two species.
- Similarity in nitrogenous bases and amino acids indicates closer genetic relationships.
Homologous Structures
- Homologous structures arise from the same embryonic tissue, despite differing in appearance.
- Example: Dolphin flippers and human hands share structural similarities due to common ancestry.
Analogous Structures
- Analogous structures have similar functions and superficial similarities but lack a common evolutionary origin.
- Example: The wings of birds and insects serve the same function (flight) but developed independently.
Fossil Formation
- Fossils are primarily found in sedimentary rock, formed from sediments settling over dead organisms.
- Oldest fossils are located in deeper sedimentary rock layers, while younger fossils are in shallower layers.
Evidence for Evolution
- Main types of evidence supporting evolution include the fossil record, geographic distribution, and homologous structures.
Role of Vestigial Structures in Evolution
- Vestigial structures provide evidence for evolution by indicating traits that were once functional.
- Example: The human appendix suggests a role in digestion in ancestral species.
Fossil Distribution in Sedimentary Rock
- Fossils are mainly found in areas previously covered by water due to sediment deposition that protects remains.
Evolutionary Evidence in Fossils
- Similar, but not identical fossils across different layers indicate evolutionary changes between species.
Vestigial Bones in Whales
- Pelvic bones in whales serve as vestigial structures, hinting at an evolutionary past where ancestors had legs.
Cladograms
- Cladograms visually depict evolutionary relationships and common ancestors among species.
- Organisms more distantly related on a cladogram share fewer amino acid sequences.
Index Fossils
- Index fossils are identifiable organisms that lived during a brief geological timeframe and widespread distribution, useful in dating layers of rock.
Amino Acid Sequences and Relationships
- A high similarity in amino acid sequences suggests a closer evolutionary relationship between organisms.
- Conversely, significant differences indicate less relatedness.
DNA and Common Ancestor
- The presence of DNA in all organisms supports the idea of a common ancestor.
Comparative Embryology
- Comparative embryology examines the embryonic stages of various species, revealing similarities that provide insights into evolutionary relationships.
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Description
This quiz covers essential biology concepts related to vestigial structures and methods for determining the relatedness of species. Test your knowledge on examples and definitions of key terms in evolutionary biology. Ideal for students studying biology concepts.