Name:_________________
HR: _____
Unit 6 Heredity Worksheet
Part one of this worksheet should be a review from your notes. However, there is a little more
information I would like you to gain from Chapter 7 in your textbook; turn to page 192 (7.2).
Codominance
1. Define Codominance
2. Blood type is an example of Codominance as well as Multiple Alleles. What are
the three alleles for blood type (write them how they are shown in the
textbook)?
3. How can two people with type A blood have a child with O blood? Draw a
Punnett square to support your claim.
Many genes may interact to produce one trait
4. Define Polygenic traits.
5. Human skin color, for example, is the result of _______ genes that interact to
produce a ___________________ of color. What is the second example they use?
6. How do multiple-allele traits differ from polygenic traits? Use examples to
justify your response.
Nature vs Nurture
7. What example was given for how environment can effect genotype/phenotype?
How does it affect these creatures?
Compare & Contrast
8. How are codominant alleles and incompletely dominant alleles similar? How are
they different?
7.3 Gene Linkage & Mapping
9. Why did Thomas Hunt Morgan use fruit flies? What 3 traits did he follow?
10. Morgan’s results did not turn out to be the expected 9:3:3:1 ratio. Why…what
explanation did he come to?
11. Morgan also concluded that chromosomes must exchange homologous genes
during which process? What is that called (the exchange of genes)?
12. Is the distance between genes on a chromosome important? Why or why not?
_____________________________________Part 2__________________________________________
7.4 Human Genetics & Pedigrees
Now this stuff IS new, and this is your “notes” for pedigrees, so pay attention and study it
well!!!
1.
In what process are chromosomes independently assorted into 4 haploid daughter cells?
What restores them into diploid cells?
2.
What are the three chromosomal disorders, mentioned in the text, that are caused by a
single Dominant/recessive gene?
3.
Why can’t males be carriers of sex-linked diseases?
4.
What are the six sex-linked traits found on the X chromosome in figure 4.2?
5.
Describe the disorder of the British royal family.
6.
A __________________ can help trace phenotypes and genotypes once enough family
members are involved genotypes can typically be inferred.
7. What are the rules for pedigrees?
Male 
Person showing the trait
Female 
Carriers 
8. Direct lines between a male and a female show marriage (or biological connections).
Look at figure 4.3 as a guide and draw a mother and father who have two girls and one
boy.
9. Just by looking at a pedigree, how can you determine if a gene is sex-linked or
autosomal?
10. When looking at an autosomal trait, anyone who does not show the trait must have a
____________________ genotype.
11. What are the 3 steps given to you to figure out widow’s peak? (summarize each step)
12. Is the following pedigree autosomal or sex-linked? Use individuals from the pedigree to
support your answer.
13. Looking at the pedigree above, what is the genotype of Mom & Dad?
14. What is the Genotype for the first daughter? (II 2) How do you know this?
15. Go ahead and color in any carrier, and write in as many genotypes as you can!