Populations Structure

The body structures for a population of chimpanzees were stable for a long time. Then, their body structures changed, making the chimpanzees stronger. Why did this happen?

• Their environment must have changed.

• Organisms naturally become stronger over time.

• It is impossible to say without more information

• The chimpanzee population wanted to be stronger.

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This fossil turtle and this living hawk both have a structure in their neck called the atlas bone. What best explains why both species have an atlas bone?

• The turtle and hawk are different species, so they must not share an ancestor population. They inherited their atlas bone structure from separate ancestor populations.

• The turtle and hawk both share the same ancestor population that had an atlas 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 turtle’s ancestors, and we cannot explain its body structures.

• All species have their own specific body structures, so it is a coincidence that this turtle and hawk each happen to have the atlas bone structure.

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This fossil pterodactyl and this living elephant both have a bone in their hip called the ilium. What best explains why both species have an ilium?

• The pterodactyl and elephant both share the same ancestor population that had an ilium bone. They inherited this structure from the ancestor population.

• All species have their own specific body structures, so it is a coincidence that the pterodactyl and elephant each happen to have the ilium bone structure.

• It is impossible to say. Fossils are very old; therefore, we cannot make observations of the pterodactyl’s ancestors, and we cannot explain its body structure.

• The pterodactyl and elephant are different species, so they must not share an ancestor population. They inherited their ilium bone structures from separate ancestor populations.

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This fossil trilobite and this living blue crab both have a limb structure called a biramous limb. What best explains why both species have biramous limbs?

• It is impossible to say. Fossils are very old, so we cannot make observations of the trilobite’s ancestors, and we cannot explain its body structures.

• The trilobite and blue crab both share the same ancestor population that had a biramous limb. They inherited this structure from the ancestor population.

• All species have their own specific body structures, so it is a coincidence that this trilobite and blue crab each happen to have the biramous limb structure.

• The trilobite and blue crab are different species, so they must not share an ancestor population. They inherited their biramous limb structure from separate ancestor populations.

Tags

NGSS.MS-LS4-1

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European moles and Sumatran tigers both have eyes. However, European moles live completely in the dark and have very small eyes, while Sumatran tigers have large eyes that can see prey from far away. What most likely explains why both European moles and Sumatran tigers have eyes and why their eyes are different?

• The European mole and Sumatran tiger both inherited eyes from a shared ancestor population, but this population separated into different environments. In each environment, different eye types evolved, which helped the populations survive.

• All species have their own specific body structures, so it is a coincidence that the European mole and Sumatran tiger each happen to have different types of eyes.

• The European mole and Sumatran tiger are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved the type of eyes that help 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.

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This red kangaroo and this alpine newt both have a femur bone in their back limbs. However, their femur bones are very different. The red kangaroo has long femur bones that help it jump very far. The alpine newt has short femur bones that help it swim. What most likely explains why both have back limbs with a femur and why the femur bones are different?

• The red kangaroo and alpine newt are different species, so they do not share an ancestor population. These species had separate ancestor populations, and each evolved femur bones that help it survive in its environment.

• 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 red kangaroo and alpine newt both inherited femur bones from a shared ancestor population, but this population separated into different environments. In each environment, different types of femur bone evolved, which helped the populations survive.

• All species have their own specific body structures, so it is a coincidence that the red kangaroo and alpine newt each happen to have femur bones that are different.

Tags

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This octopus and this fossil ammonite both have a body structure in their mouths called a radula. The radula is a structure used for eating. What best explains why both species have a radula?

• All species have their own specific body structures, so it is a coincidence that this octopus and ammonite each happen to have a radula structure.

• The octopus and ammonite both share the same ancestor population that had a radula. They inherited this structure from the ancestor population.

• It is impossible to say. Fossils are very old; therefore, we cannot make observations of the ammonite’s ancestors, and we cannot explain its body structures.

• The octopus and ammonite are different species, so they must not share an ancestor population. They must have inherited radulas from separate ancestor populations.

Tags

NGSS.MS-LS4-1

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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

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

• All three species share an ancestor population, but the sea cucumber and the cuttlefish share a more recent ancestor population. This is why they share the intestine structure.

• 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 cucumbers and cuttlefish share an ancestor population, but they must not share an ancestor with the ctenophore because ctenophores don’t have the intestine 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.

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This blue tang, this tortoise, and this Brazilian rainbow boa have similarities and differences in their body structures. What does the information about these structures tell you about the ancestors of these species?

• 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.

• All three species share an ancestor population, but tortoises and Brazilian rainbow boas share a more recent ancestor population. This is why they share the quadrate bone structure.

• Tortoises and Brazilian rainbow boas share an ancestor population, but they must not share an ancestor with blue tangs because blue tangs have no quadrate bone.

Tags

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