Analyze Evolutionary Relationships Through Body Structures

Front

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?

Back

The snake and rat both share the same ancestor population that had a quadrate bone. They inherited this structure from the ancestor population.

Answer explanation

The correct choice explains that both the snake and rat inherited the quadrate bone from a common ancestor. This shared structure indicates their evolutionary relationship, rather than being a coincidence or unrelated traits.

Front

Why do both the bird and salamander have tails, and why are their tails different?

Back

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.

Answer explanation

The correct choice explains that both the bird and salamander inherited tails from a shared ancestor. As they adapted to different environments, their tails evolved differently to enhance survival, reflecting evolutionary changes.

Front

What does the diagram showing evolutionary relationships between the African elephant, Sumatran tiger, and Norway rat indicate?

Back

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.

Answer explanation

The diagram indicates that all three species share a common ancestor. However, the Sumatran tiger and Norway rat are more closely related to each other than to the African elephant, making the correct choice clear.

Front

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?

Back

The jumping spider and eurypterid both share the same ancestor population that had chelicerae. They inherited this structure from the ancestor population.

Answer explanation

The correct choice explains that both the jumping spider and eurypterid inherited chelicerae from a common ancestor population. This shared trait indicates a common evolutionary origin, rather than coincidence or separate ancestry.

Front

What does the information about the body structures of the red-eared slider, greater flamingo, and siamang tell you about their ancestors?

Back

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.

Answer explanation

All three species share a common ancestor, but the red-eared slider and greater flamingo have a more recent ancestor, explaining their shared egg-laying trait, while the siamang's live birth indicates a different evolutionary path.

Front

Why did the body structures of green herons change to make them taller after being stable for a long time?

Back

Their environment must have changed

Answer explanation

The change in body structure of the green herons indicates an adaptation to a new environment. Taller herons may have better access to food or improved visibility, suggesting that their environment must have changed.

Front

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?

Back

The manta ray and shark both share the same ancestor population that had a cartilage skeleton. They inherited this structure from the ancestor population.

Answer explanation

The manta ray and shark share a common ancestor that had a cartilage skeleton. This trait was inherited from that ancestor, explaining why both species have similar skeletal structures.

Front

Why do both the octopus and surf clam have mantles, and why are their mantles different?

Back

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.

Answer explanation

The octopus and surf clam inherited their mantle from a shared ancestor. As they adapted to different environments, their mantles evolved differently to enhance survival, explaining the structural differences.

Front

What does this diagram show?

Back

All three species share a common ancestor, but the bold jumping spider and Bombay locust are more closely related to each other than they are to the common octopus.

Answer explanation

The diagram indicates that all three species share a common ancestor. However, the bold jumping spider and Bombay locust are more closely related to each other than to the common octopus, making the first answer choice correct.

Front

This living sea star and fossil sea urchin both have body structures that are formed along five lines. What best explains why both species have this five-lined body structure?

Back

The sea star and sea urchin both share the same ancestor population that had a five-lined body structure. They inherited this structure from the ancestor population.

Answer explanation

The sea star and sea urchin share a common ancestor that had a five-lined body structure, which they inherited. This explains the similarity in their body structures despite being different species.