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Name: _________________________________________ Block: __________ Date: _________________
Biology – Mrs. Northup
Genetics Homework Questions (Chapter 11-1 to 11-3 and Chapter 14-1 to 14-2)
Directions: On a separate piece of paper, answer the following questions in complete
sentences (unless you are asked to create a diagram or chart). You may also email your
responses to [email protected].
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Introduction to Genetics (pp. 262-274)
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Chapter 11-1
The Work of Gregor Mendel
Due: __________________
1) Seed color and flower color are two pea plant traits. Name any two human traits.
2) What determines our or any organism’s traits?
3) State the Principle of Dominance.
4) Alleles are the different forms of a gene. If I am referring to the gene that determines hair
color, what are the different alleles for hair color?
5) Complete the following sentence: An organism with a _______________ allele for a
particular trait will ALWAYS HAVE THAT FORM, however, an organism with a _______________
allele will ONLY HAVE THAT FORM when the _______________ allele IS NOT PRESENT.
6) Segregation of alleles happens when gametes or sex cells are made. So during what
process does segregation occur?
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Chapter 11-2
Probability and Punnett Squares
Due: __________________
1) Define probability in your own words.
2) What is a Punnett Square? What goes on the left and top of the outside of the entire
square? What goes in the inside of the individual squares?
3) Complete the following Punnett square.
B
b
B
b
4) What is the difference between and organism that is homozygous and one that is
heterozygous for a particular trait?
5) Complete the following sentence: _____________________ describes the physical
characteristics of an organism and ____________________ refers to an organism’s genetic
makeup.
6) How is the use of probability to predict averages in genetics analogous to doing multiple
trials in a lab experiment?
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Chapter 11-3
Exploring Mendelian Genetics
Due: __________________
1) Complete the following sentence about the Principle of Independent Assortment with the
correct phrase: Genes that segregate independently DO NOT ____________________________.
2) A woman has black curly hair with blue eyes has a child with a man that has straight
blond hair and brown eyes. Describe what one of their children could look like if hair color,
hair texture, and eye color all assort independently.
3) If a gene for a particular flower’s color is incompletely dominant, what color would the
offspring of a purebred yellow and a purebred red plant be?
4) If a gene that determines fur color in a particular cat is co-dominant, what would the
offspring of a purebred black and a purebred white cat look like?
5) Human blood type is determined by a gene with multiple alleles. What are all the different
human blood types (ask someone at your house or it’s in Chapter 14)?
6) What kind of evidence show a trait is polygenic (determined by multiple genes) such as
human height?
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The Human Genome (pp. 340-343 and pp. 349-353)
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Chapter 14-1
Human Heredity
Due: __________________
1) Why do scientists use a cell that is in mitosis to create a karyotype (picture of
chromosomes)?
2) What is a zygote? What process creates a zygote?
3) Complete the following sentence: The sex chromosomes of a male are ________, whereas
the sex chromosomes of a female are ________.
4) What does a pedigree chart resemble (maybe something you’ve seen in History class)?
5) Other than your genes, what are two factors that influence your traits?
STOP READING AT THE END OF PAGE 343 FOR THIS SECTION.
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Chapter 14-2
Human Chromosomes
Due: __________________
1) What are sex-linked genes?
2) Why are all X-linked alleles expressed in males even if they are recessive?
3) What happens to the sex cells if non-disjunction occurs during meiosis?
4) What disease results from non-disjunction of the 21st chromosome?
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Alternative Assessment:
Instead of completing the questions for sections 11-1 to 11-3 and 14-1 to 14-2 above, you
may answer the four following open response questions to take their place.
1) Corn snakes show variety in their skin color pattern. While the complete genetics of corn
snake color are complex, the most common colors on normal corn snakes—red and black—
are each coded by one gene.
For the red gene, the allele for the presence of red pigment (R) is dominant and the allele for
the absence of red pigment (r) is recessive. Likewise, for the black gene, the allele for the
presence of black pigment (B) is dominant and the allele for the absence of black pigment
(b) is recessive.
a. Draw the Punnett square for the cross of a snake that is homozygous dominant for the red
color with a snake that is heterozygous for the red color. What percentage of the offspring
is expected to have red pigment in their skin?
b. Draw the Punnett square for the cross of two snakes that are heterozygous for the black
color. What percentage of the offspring are expected to have black pigment in their skin?
c. The parent snakes in part (b) that are heterozygous for black color are both homozygous
recessive for the red gene. Each parent has genotype rr for the red gene. Based on this
information, what percentage of their offspring are expected to lack both the red and black
pigments in their skin? Explain your reasoning.
2) Describe the difference between the phenotype expressed in a heterozygote when the
alleles display complete dominance, incomplete dominance, and co-dominance. Provide
an example of each type of dominance in humans.
3) Coat color in a certain species of rabbits in determined by one gene with multiple alleles.
The alleles are listed in the chart below in order of dominance and the phenotype that is
expressed. Use the chart to answer the questions that follow.
Allele
R
rh
rch
r



Phenotype
Black fur
Himalayan (white fur on the body, black fur on nose, ears, feet, tail)
Chinchilla (gray fur all over the body)
White fur (albino)
R is dominant to rh, rch, and r.
rh is dominant to rch and r.
rch is dominant to r.
a. Gina has a rabbit with genotype rhr. Identify the phenotype of Gina’s rabbit.
b. Identify all possible genotypes for a black rabbit.
c. Gina breeds her rabbit with a black rabbit. The phenotype ratio of the offspring of
Gina’s rabbit and the black rabbit is 2 black : 1 Himalayan : 1 chinchilla. Identify the
genotype of the black rabbit in this cross. Support your answer by drawing the
Punnett square for the cross.
4) Some people have difficulty identifying different pitches of sound or recognizing different
tunes. These people are said to be "tune deaf." Scientists have evidence that tune deafness
is genetic. The pedigree below traces the inheritance of tune deafness in a family.
Individuals in the pedigree are numbered.
Scientists have analyzed the inheritance patterns for tune deafness and have concluded
that tune deafness is probably caused by an autosomal dominant allele.
a. What evidence from this pedigree confirms that this is an autosomal dominant allele and
not a sex-linked allele?
b. Provide evidence from this pedigree that supports the conclusion that tune deafness is
caused by an autosomal dominant allele. Explain your reasoning.
c. How would this pedigree differ if the disorder was caused by an autosomal recessive
allele?