IB Biology Topic A4.1.4 Evidence for Evolution from Homologous Structures Revision Notes (SL/HL)

IB Biology Topic A4.1.4 Evidence for Evolution from Homologous Structures Revision Notes (SL/HL) | RevisionDojo

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Same Skeleton, Different Jobs: Homologous Structures Point to a Common Ancestor

Definition

Homologous structures

Homologous structures are anatomical features that share a similar structure and position across different species but serve different functions.

Homologous structures share the same underlying structure but are used for different functions.
That shared plan is evidence of inheritance from a common ancestor, the pattern we call divergent evolution.
Darwin called this shared design unity of type.

Example

A human hand grasps, a bird wing flies, and a whale flipper swims, yet all share the same bone arrangement.

The Pentadactyl Limb Is the Classic Homologous Structure

The pentadactyl limb is the five-digit limb pattern shared by all tetrapods.
Its bones run in the same order from the body outward:

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(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Same Skeleton, Different Jobs: Homologous Structures Point to a Common Ancestor

Definition

Homologous structures

Homologous structures are anatomical features that share a similar structure and position across different species but serve different functions.

Homologous structures share the same underlying structure but are used for different functions.
That shared plan is evidence of inheritance from a common ancestor, the pattern we call divergent evolution.
Darwin called this shared design unity of type.

Example

A human hand grasps, a bird wing flies, and a whale flipper swims, yet all share the same bone arrangement.

The Pentadactyl Limb Is the Classic Homologous Structure

The pentadactyl limb is the five-digit limb pattern shared by all tetrapods.
Its bones run in the same order from the body outward:

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic A4.1.4: Evidence for Evolution from Homologous Structures Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Same Skeleton, Different Jobs: Homologous Structures Point to a Common Ancestor

The Pentadactyl Limb Is the Classic Homologous Structure

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Same Skeleton, Different Jobs: Homologous Structures Point to a Common Ancestor

The Pentadactyl Limb Is the Classic Homologous Structure

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account