Evolutionary History Final Test

This fossil snake and this living rat both have a structure in their skull called the quadrate bone. What best explains why both species have a quadrate bone?

• The snake and rat are different species, so they must not be related. They inherited the quadrate bone structure from separate ancestor populations.
• All species have their own specific body structures, so it is a coincidence that the snake and rat each happen to have the quadrate bone structure.
• The snake and rat both share the same ancestor population that had a quadrate bone. They inherited this structure from the ancestor population.
• It is impossible to say. Fossils are very old; therefore, we cannot make observations of the snake’s ancestors, and we cannot explain its body structures.

This fossil bird and this living salamander both have tails. However, they have different tail structures. The bird has a very short tail made of just one bone that helps it have a light skeleton for flying. The salamander has a long tail with many bones that helps it balance while it runs. What most likely explains why both the bird and salamander have tails and why the tails are different?

• The salamander and bird both inherited tails from a shared ancestor population, but this population separated into different environments. In each environment, different types of tails evolved, which helped the populations survive.
• It is impossible to explain the body structures of different species. The way that structures change over time is very complex, and no one has ever observed these changes occurring.
• The bird and salamander are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved a tail that helps it survive in its environment.
• All species have their own specific body structures, so it is a coincidence that the bird and salamander happen to have different types of tails.

This bandicoot, this sea lion, and this zebra have similarities and differences in their body structures. What does the information about these structures tell you about the ancestors of these species?

• Sea lions and zebras share the same ancestor population, but they must not share an ancestor with bandicoots because sea lions and zebras do not have a pouch for their babies.
• None share an ancestor population because different species cannot share an ancestor population. It is a coincidence that these species have some of the same body structures.
• All three species share an ancestor population, but sea lions and zebras share a more recent ancestor population. This is why neither shares the pouch structure for their babies.
• We cannot make observations of ancestor populations from the past. It is impossible to explain ancestors with only the information about the body structures of different species.

What does this diagram show?

• All three species share a common ancestor, but the African elephant and Sumatran tiger are more closely related to each other than they are to the Norway rat.
• All three species share a common ancestor, but the Sumatran tiger and Norway rat are more closely related to each other than they are to the African elephant.
• The Sumatran tiger, African elephant, and Norway rat are not related and come from separate lines of evolutionary history.
• All three species share a common ancestor and are equally related to each other.

This living jumping spider and this fossil eurypterid both have body structures called chelicerae. Chelicerae are a body structure used for eating. What best explains why both species have chelicerae?

• It is impossible to say. Fossils are very old; therefore, we cannot make observations of the eurypterid’s ancestors, and we cannot explain its body structures.
• The jumping spider and eurypterid are different species, so they must not share an ancestor population. They inherited chelicerae from separate ancestor populations.
• All species have their own specific body structures, so it is a coincidence that this jumping spider and eurypterid each happen to have a chelicerae structure.
• The jumping spider and eurypterid both share the same ancestor population that had chelicerae. They inherited this structure from the ancestor population.

This red-eared slider, this greater flamingo, and this siamang have similarities and differences in their body structures. What does the information about these structures tell you about the ancestors of these species?

• The red-eared slider and the greater flamingo share an ancestor population, but they must not share an ancestor with the siamang because red-eared sliders and greater flamingos lay eggs, but siamangs give live birth.
• All three species share an ancestor population, but the red-eared slider and the greater flamingo share a more recent ancestor population. This is why they share the egg-laying structure.
• We cannot make observations of ancestor populations from the past. It is impossible to explain ancestors with only the information about the body structures of different species.
• None share an ancestor population because different species cannot share an ancestor population. It is a coincidence that these species have some of the same body structures.

This sea anemone and this ctenophore both have tentacles, which are body structures that help them catch food. However, sea anemone tentacles are short and can sting, while ctenophore tentacles are long for grabbing and cannot sting. What most likely explains why both species have tentacles and why the tentacles are different?

• Sea anemone and ctenophore both inherited tentacles from a shared ancestor population, but this population separated into different environments. In each environment, different types of tentacles evolved, which helped the populations survive.
• It is impossible to explain the structures of different species. The way structures change over time is very complex, and no one has ever observed these changes occurring.
• This sea anemone and ctenophore are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved tentacles that help it survive in its environment.
• All species have their own specific body structures, so it is a coincidence that the sea anemone and ctenophore happen to have different types of tentacles.

The body structures for a population of green herons (a species of bird that lives near water) were stable for a long time. Then, their body structures changed to make the green herons taller. Why did this happen?

• It is impossible to say without more information.
• The green heron population wanted to be taller.
• Their environment must have changed.
• Organisms naturally become taller over time.

This living manta ray and this fossil shark both have a skeleton made of cartilage (which is softer than bone). What best explains why both species have a skeleton like this?

• The manta ray and shark are different species, so they must not share an ancestor population. They inherited cartilage skeletons from separate ancestor populations.
• The manta ray and shark both share the same ancestor population that had a cartilage skeleton. They inherited this structure from the ancestor population.
• All species have their own specific body structures, so it is a coincidence that the manta ray and shark each happen to have a cartilage skeleton structure.
• It is impossible to say. Fossils are very old; therefore, we cannot make observations of the shark’s ancestors, and we cannot explain its body structures.

This octopus and this surf clam both have a body structure called a mantle, which covers their soft bodies. However, the mantle is shaped differently in the two species. The octopus’s mantle has muscles that help the octopus swim. The surf clam’s mantle helps the clam build its shell. What most likely explains why both the octopus and surf clam have mantles and why the mantles are different?

• All species have their own specific body structures, so it is a coincidence that the octopus and surf clam each happen to have mantle structures that are different.
• The octopus and surf clam are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved a mantle that helps it survive in its environment.
• It is impossible to explain the body structures of different species. The way that structures change over time is very complex, and no one has ever observed these changes occurring.
• The octopus and surf clam both inherited the mantle structure from a shared ancestor population, but this population separated into different environments. In each environment, different types of mantle evolved, which helped the populations survive.