L.8.4B.4--Evolutionary Relationships

This period is generally divided into three: germinal, embryonic, and fetal.

• common ancestry
• egg
• embryonic stages
• development

A change in the inherited characteristics of an organism over time is ________

• evolution.
• development.
• growth.
• ancestry.

Another word for specific parts that form an organ, system, or living thing is __________.

• structure.
• vertebrae.
• forelimb.
• organism.

_____________  is the study of embryos to see how their similarities and differences indicate an evolutionary relationship.

• Paleontology
• Common ancestry
• Homologous structure
• Embryology

The most recent ancestral form or species from which two different species evolved is known as ________________________.

• a common ancestor.
• an embryonic stage.
• development.
• evolution.

In stage one (top row) of these embryos, most of the embryos________

• look very similar.
• have very different features.
• show different stages of development.
• have only a tail if they are non-human.

In stage 2 (middle row) fish embryos _________

• are very different bird and mammal embryos.
• are still very similar to bird and mammal embryos.
• show arm and leg buds.
• are the only embryos with tails.

In the the third embryonic stage (bottom row), mammal embryos _____

• have more characteristics in common with each other than with reptiles or birds.
• are still hard to tell from reptiles and birds.
• have the same features as fish, reptiles, and birds.
• do not have tails.

The more similar the stages of embryonic development, the more likely that organisms share ____________

• a common ancestor.
• embryos.
• eggs.
• embryology.

Structures that are inherited from a common ancestor are homologous.

• True
• False