Claim-Evidence-Reasoning (CER)
Prompt (Question): ​A woman finds an extremely rare newborn purple unicorn for sale. She has been
searching for a purple unicorn for years, but before she buys the baby unicorn, she wants to learn more about
its pedigree.
The breeder says that the baby unicorn’s mother is orange, but he does not know the mother’s genotype. The
breeder also owns two male unicorns, but he is not sure which one is the father. ​One of the male unicorns is
purple with a genotype Pp​, and the other male is orange with an unknown genotype.
Which unicorn is the father of the mysterious purple unicorn?​ Construct an argument based on what you
know about Mendelian inheritance to determine which unicorn is the father of the purple unicorn.
Hint: ​Which color is the dominant trait - orange or purple?
Claim​: (Answer question in 1-2 full sentences.)
Evidence:​ (Write down evidence to support your claim. 2-4 sentences)
Reasoning: ​(Explain why your evidence supports your claim. Be sure to explain how you determined the
genotypes of the mother and baby unicorn. 2-4 sentences)
Created by HISD Secondary Science Curriculum and Development, 2019