Biology Flashcards on Structures

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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.

Analogous structures are similar in function and structure but not derived from a common ancestor. An example is the wings of birds and insects. Signup and view all the answers

Where would a scientist likely find a fossil?

In sedimentary rock. Signup and view all the answers

List the 3 types of evidence for evolution.

Fossil record, geographic distribution, homologous structures. Signup and view all the answers

How do vestigial structures add to the evidence of evolution?

Vestigial structures show that organisms contain unused structures that may have been functional in their ancestors. Signup and view all the answers

Where are the oldest fossils found in sedimentary rock? Where are the youngest fossils found?

Oldest fossils are found in deep layers of sedimentary rock; youngest fossils are in shallow layers. Signup and view all the answers

What causes sedimentary rock?

Sediments in rivers and streams settle on dead organisms, covering them and protecting them from the environment. Signup and view all the answers

Why are most fossils found in areas that once were covered with water?

Most sediment is formed and deposited in water areas, providing a suitable environment for fossilization. Signup and view all the answers

Why might a scientist find fossils in different layers of rock that are similar but not exact copies of each other?

One organism may have evolved from another, resulting in similar but distinct fossil remains. Signup and view all the answers

Why do some whales have a pelvic bone although they have no legs?

The pelvic bone is a vestigial structure, indicating that whales may have had legs in the past. Signup and view all the answers

Would two organisms on a cladogram that are far apart have more or less amino acids in common?

They would have less amino acids in common. Signup and view all the answers

What is a cladogram? What can a cladogram tell us?

A cladogram is a diagram that represents evolutionary relationships between species, showing common ancestors. Signup and view all the answers

What is an index fossil?

An index fossil is a fossil of an easily identifiable organism that existed for a short period in a wide geographic range. Signup and view all the answers

If 2 organisms have many of the same amino acid sequences, they would be __________ related to each other.

more Signup and view all the answers

If 2 organisms do not have many of the same amino acid sequences, they would be __________ related to each other.

less Signup and view all the answers

What can the amino acid sequences between two organisms tell us?

They can show how closely related 2 organisms are to each other. Signup and view all the answers

What does the fact that all organisms have DNA tell us about a common ancestor?

It indicates that all organisms have a common ancestor. Signup and view all the answers

What is comparative embryology and what does this tell us about evolution?

Comparative embryology is comparing the embryos of different species, indicating evolutionary relationships. Signup and view all the answers

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.