Page 181 - Big Ideas Year 10 sciPAD 2025

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SCIPAD - BIG IDEAS - BOOK 2
THE BASIS OF HEREDITY
Feature
5. The diagram above shows the skeleton of a modern Right whale. Using the information
from the previous page, suggest a reason for the presence of the feature identified.


Vestigial Structures
The pelvis and leg bones found in whales are an example of what scientists call vestigial structures.
A vestigial structure is a body part in a modern organism that once functioned in the ancestors of
the organism, but lost its usefulness in their descendents. Vestigial structures tend to be reduced in
size and have little or no function. Vestigial structures are considered a valuable piece of evidence
for evolution.
1. What is a vestigial structure? 

2. Name two vestigial structures found in humans. 

3. New Zealand has more flightless birds than anywhere else in the world. This is
mainly due to the fact that New Zealand had no land mammals (such
as cats, dogs and rats) that would normally prey on birds. However, we
did have predatory birds that hunted in the skies and in the canopy of
trees.
(a) What feature of a kiwi is vestigial? 
(b) What does this vestigial feature suggest about the ancestors of
modern kiwis? 

(c) What do kiwis eat? 
(d) Where in the forest do they find this food? 
(e) Use the information at the start of the question, and your answers to questions
(c) and (d), to suggest a reason why the structure you name in (a) has become
vestigial. 





(f) What evidence would you need to support your theory from (e)?


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