Key Idea: Similarities and differences in inherited characteristics of organisms alive today or in the past can be used to infer the relatedness of any two species, changes in species over time, and lines of evolutionary descent.

Students are expected to know that:

  1. The similarities among living things suggest relatedness.
  2. The fact that organisms retain some of the inherited characteristics of their ancestors from many generations ago makes it possible for scientists to identify both recent and past ancestors of those organisms.
  3. Inherited characteristics (both internal and external) of species alive today, including their DNA, can be compared to determine how similar the species are. Organisms with more similarities are usually more closely related to each other than organisms with fewer similarities, i.e., organisms that have more similarities tend to have a more recent common ancestor than those with fewer similarities.
  4. Inherited characteristics (both internal and external) of species alive today can be compared to the characteristics of species that lived in the past, including their DNA if available, to determine how similar they are. Organisms with more similarities are usually more closely related to each other than organisms with fewer similarities, i.e., organisms that have more similarities tend to have a more recent common ancestor than those with fewer similarities.
  5. Some structures that do not seem similar in gross structure and function (e.g. the hand of a human and the front flipper of a whale) may after closer analysis of the detailed anatomy and their DNA sequences be shown to have the same origin. A comparison of these homologous structures and the embryonic structures from which they arise can help to infer lines of evolutionary descent.
  6. The relative ages of fossils can be used to help infer lines of evolutionary descent. Relative ages of fossils are determined by their relative positions in the earth's rock layers.
  7. Fossils, anatomy, and embryos provide corroborative lines of evidence for common ancestry. DNA underlies the similarities and differences in fossils, anatomy, and embryos.
  8. Cladograms and tree diagrams can be used to represent lines of evolutionary descent and to organize hypotheses about the relationships among living things.
  9. Evidence for common ancestry across a wide variety of species provides support for the idea that all multi-cellular organisms (including humans) share a common ancestor. Evidence also indicates that life began as single-celled organisms and that complex multi-cellular organisms evolved from them.
  10. The similarities and differences in all living organisms are explained by their evolution from common ancestors.

Boundaries:

  1. Students are not expected to know about convergent evolution.
  2. Students are not expected to know about Archae bacteria and the possible multiple origins of life.
  3. Students are not expected to know methods of dating.
  4. Students are not expected to know the approximate date of the origin of life or when any particular species or type of organism originated.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number
Knowledge Being Assessed Grades
6–8
Grades
9–12
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CA043005

Chimpanzees and gorillas have a more recent common ancestry than chimpanzees and orangutans because their average genetic similarity is greater. (Identify correct evidence and reasoning to support a claim.)

N/A

N/A

CA010002

If the DNA of jellyfish and insects is more similar than the DNA of jellyfish and plants, then jellyfish and insects share a more recent common ancestor than jellyfish and insects.

N/A

N/A

CA017003

Organisms that have more traits in common are also more genetically similar.

See the Evolution Project

CA034002

Organisms whose DNA sequences for a certain gene are more similar than those of another organism, are also more closely related.

See the Evolution Project

EN050005

All plants and all animals have a common ancestor with each other.

See the Evolution Project

CA011002

If the DNA of Species X and Species Y is more similar than the DNA of Species X and Species Z, then Species X and Species Y have a more recent common ancestor than Species X and Species Z.

See the Evolution Project

CA040003

Scientists can use similarities in the embryos of two animal species to help determine how closely they are related.

See the Evolution Project

CA016003

Organisms that have more traits in common share a more recent common ancestor than organisms with fewer traits in common.

See the Evolution Project

CA012001

Identify the diagram that most likely depicts the ancestry of lizards, toads, and dogs if the DNA of lizards and dogs is more similar than the DNA of lizards and toads.

See the Evolution Project

CA009004

If the DNA of lizards and dogs is more similar than the DNA of lizards and toads, lizards and dogs share a more recent common ancestor than lizards and toads.

See the Evolution Project

CA045002

Having a similar DNA sequence suggests common ancestry (sharks and dolphins).

See the Evolution Project

EN047005

Living species can share ancestors with other living species, and they can share ancestors with extinct species.

See the Original Project

CA024003

Many of the same genes code for homologous traits (forelimbs) across different species.

See the Evolution Project

CA043004

Chimpanzees and gorillas have a more recent common ancestry than chimpanzees and orangutans because their average genetic similarity is greater. (Itentify correct claim, evidence, reason.)

See the Evolution Project

CA023003

Many of the same genes code for homologous traits (forelimbs) across different species.

See the Evolution Project

CA047002

The fact that fish cells and algae both have DNA can be used as evidence that they share a common ancestor. (Provide valid evidence and sound reasoning to support a claim.)

See the Evolution Project

EN049005

All dogs and cats share a common ancestor.

See the Evolution Project

CA026004

Many of the same genes code for homologous traits (forelimbs) across different species.

See the Evolution Project

CA032003

Different species can have similar genes for similar traits because they inherit them from a common ancestor.

See the Evolution Project

EN047003

A species living today and an extinct species could share a common ancestor that lived a very long time ago, even if the two species have few similarities.

See the Original Project

CA025002

Many of the same genes code for homologous traits (forelimbs) across different species.

See the Evolution Project

CA015003

Organisms that have more traits in common are probably more closely related than organisms with fewer traits in common.

See the Evolution Project

CA041002

Similar skeletal features in organisms (chimpanzees and gorillas) indicate a common ancestor.

See the Evolution Project

EN046010

Cats, dogs, fish, and birds all share an ancient common ancestor.

See the Evolution Project

CA014003

Organisms that have fewer traits in common are probably more distantly related than organisms with more traits in common.

See the Evolution Project

CA020003

Organisms that have more traits in common share a more recent common ancestor than organisms with fewer traits in common. (Tree diagram)

See the Evolution Project

CA042002

Similar skeletal features (in dogs and fish) indicate a common ancestor. (Identify claim, evidence, and reasoning.)

See the Evolution Project

EN046012

Chimpanzees, humans, zebras, and worms all share an ancient common ancestor.

See the Evolution Project

CA022003

Fossils can be used to determine how closely organisms are related.

See the Evolution Project

EN050002

All plants and all animals have a common ancestor with each other.

See the Original Project

EN049002

All dogs and cats share a common ancestor.

See the Original Project

EN048003

All plants and animals -- including humans -- came from a common ancestor.

See the Original Project

EN046003

Cats, dogs, fish, and birds all share an ancient common ancestor.

See the Original Project

EN046004

Chimpanzees, humans, zebras, and worms all share an ancient common ancestor.

See the Original Project

EN046007

Chimpanzees, humans, chickens, and oak trees all share an ancient common ancestor.

See the Original Project