Changes Over Time

Essential Question How do life forms change over time? Have you ever had to adapt to a new situation? How did adapting help you adjust? Take 5 minutes and discuss with your group. Write your answer in your notes. Be prepared to share with the class.

Evidence of Evolution Key Questions: What is Evolution? What Evidence Supports Evolution?

Vocabulary Evolution Gene Homologous Structures Take 5 minutes and define the following words. They can be found in context between pages 374~383. Please write the definitions in your notes. Evolution Gene Homologous Structures

What is Evolution? Evolution is change over time. The scientific theory of evolution explains how living things descended from earlier organisms. Look at the picture of the modern day Elephant and the Wooly Mammoth. Discuss one similarity and one difference with your group. Do you think they share a common ancestor? Write your answer in your notes.

What Evidence Supports Evolution? Fossils, similarities in DNA and protein structures, similar body structures and patterns in early development all provide evidence that organisms have changed over time.

Fossils Compare Rocco’s jawbone to the fossilized jawbone of Metatomarctus Canavus. How do fossils tell us that these two species had a common ancestor?

Similarities in DNA and Protein Structures Remember: Genes are segments (or chunks) of DNA that determine the characteristics of an organism. Scientists compare the sequence of nitrogen bases in the DNA of two different species to determine how closely related they are. The more similar the DNA sequences, the more closely related the species are.

Similarities in DNA and Protein Structures Turn to page 381 and use the table to complete the “Apply It” section with your group. You will have 10 minutes. Write your answers in your notes and be prepared to discuss with the class.

Similarities in Body Structure Remember: “Homo” means same and “Hetero” means different. Homologous Structures: Organisms that share a common ancestor have similar bone structures. In other words: Same Ancestor = Same Structure Scientists can compare body structures of modern day organisms with fossilized remains as well as the body structures of two living organisms.

Similarities in Body Structure The bones in a bird’s wing, a dolphin’s flipper and a dog’s leg have similar structures. Turn to page 382 in your book and complete the “Interactive Art” section at the bottom of the page. You may work with your group. You will have 10 minutes.

Similarities in Body Structure

Similarities in Early Development Scientists can also infer evolutionary relationships by comparing the early development of different organisms.

Evidence of Evolution Evolution is change over time. The theory of evolution is supported by evidence that includes fossils, similarities in DNA and protein structures, similar body structures and patterns of early development.