Page 194 - Big Ideas Year 10 sciPAD 2025

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194 SCIPAD - BIG IDEAS - BOOK 2
THE BASIS OF HEREDITY
(d) Use the Punnett square below to determine the offspring of a cross between a
non-pure breeding black female (Bb) and a pure breeding white male (bb).
(i) What percentage of their offspring would you expect to be:
Black: White: 
6. Takahē are a large flightless bird related to the smaller pūkeho. Takahē are endemic (found
only in New Zealand) and have completely lost the ability to fly.
(a) Describe what is meant by the term vestigial?

(b) What does the presence of vestigial wings on a takahē suggests about its ancestors?


7. Guppies are a species of freshwater fish that show variation in the size of their tails.
(a) Sketch a graph to show the expected variation in guppy tail size.
Variation in Guppy Tail Size
Number of individuals
Small Average size Large
(b) Fossil evidence suggests that the ancestors of modern guppies had small tails.
Modern female guppies prefer to mate with males with the largest tails. Use the
‘theory of natural selection’ to explain how the large tails found in modern guppies
have evolved from their smaller tailed ancestors.







Black female
Alleles: 
White male
Alleles: 
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