Populations Structure

This Laysan albatross and this European mole both have bones in their front limbs called phalanges (finger bones). However, their phalanges are very different. The Laysan albatross has long phalanges in its front limbs, which support its long wings during flight. The European mole has short, thick phalanges in its front limbs, which help it dig in the dirt. What most likely explains why both have phalanges and why the phalanges are different?

• They are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved phalanges that help it survive in its environment.

• All species have their own specific body structures, so it is a coincidence that this Laysan albatross and European mole each happen to have phalanges that are different.

• It is impossible to explain the structures of different species. The way that structures change over time is very complex, and no one has ever observed these changes occurring.

• The Laysan albatross and European mole both inherited phalanges from a shared ancestor population, but this population separated into different environments. In each environment, different types of phalanges evolved, which helped the populations survive.

Tags

NGSS.MS-LS4-2

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This locust, this jumping spider, and this Roman snail have similarities and differences in their body structures. What does the information about these structures tell you about the ancestors of these 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.

• All three species share an ancestor population, but locusts and jumping spiders share a more recent ancestor population. This is why they share the exoskeleton structure.

• Locusts and jumping spiders share an ancestor population, but they must not share an ancestor with Roman snails because Roman snails have a shell.

Tags

NGSS.MS-LS4-2

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?

• They inherited the quadrate bone structure from separate ancestor populations.

• 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 a coincidence that the snake and rat each happen to have the quadrate bone structure.

Tags

NGSS.MS-LS4-1

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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.

• 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.

Tags

NGSS.MS-LS4-1

NGSS.MS-LS4-2

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?

• 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.

• 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.

• 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.

Tags

NGSS.MS-LS4-2

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?

• They inherited chelicerae from separate ancestor populations.

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

• It is a coincidence that this jumping spider and eurypterid each happen to have a chelicerae structure.

Tags

NGSS.MS-LS4-1

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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?

• Their environment must have changed.

• It is impossible to say without more information.

• The green heron population wanted to be taller.

Tags

NGSS.MS-LS2-4

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?

• It is a coincidence that the octopus and surf clam each happen to have mantle structures that are different.

• 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.

• It is a coincidence that the octopus and surf clam each happen to have mantle structures that are different.

Tags

NGSS.MS-LS4-2

This tortoise and this moray eel both have jaws that help them grab food. However, they have different structures in their jaws for eating. The tortoise has a bony beak that helps it bite plants. The moray eel has sharp teeth that help it eat fish. What most likely explains why both have jaws and why the jaws are different?

• It is a coincidence that this tortoise and moray eel each happen to have jaws that are different.

• Tortoises and moray eels are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved jaws that help it survive in its environment.

• Tortoises and moray eels both inherited jaws from a shared ancestor population, but this population separated into different environments. In each environment, different types of jaws evolved that help the populations survive.

Tags

NGSS.MS-LS4-2

Suppose a certain species of speckled moth lives in a forest of white trees. Some of the moths are white in color, and some are black. Assume there is a new predator of the moth in the area. What do you expect to happen to the populations of the white and the black moths over time?

• The white moth population will increase and the black moth population will decrease.

• The black moth population will increase and the white moth population will decrease.

• Both populations will increase over time.

Tags

NGSS.MS-LS2-2

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