Download Ch. 10 Study Quiz Answers

Chapter 10 Sec. 1 Study Quiz
Define the following terms in your own words: gene, chromosomes, alleles, genotype,
phenotype, homozygous, dominant, heterozygous
Gene: a piece of DNA that codes for something in your body, determines the makeup of the person.
Chromosomes: DNA packed up tightly when going through mitosis and meiosis
Alleles: Your alternate forms of a trait found on separate homologous chromosomes, one inherited from
your mom, one inherited from your dad
Genotype: your two combinations of alleles for each gene
Phenotype: your appearance or trait shown depending on your genotype
Homozygous: Meaning the same genetic material, both alleles are the same
Dominant: Sometimes you have two different alleles, the trait that is going to be exhibited will be the
dominant trait
Heterozygous: Different genetic material, the alleles are different
What does the law of dominance state?
The dominant allele will show in the phenotype even if a recessive allele is present.
What does the law of segregation state?
Allele pairs separate at random during meiosis and unite again randomly during fertilization (this is kind of
like the law of independent assortment)
Fill in the punnet square below for a homozygous tall plant and a short plant.
T
T
t
Tt
Tt
t
Tt
Tt
1. What percentage of offspring is predicted to
be heterozygous?
100%
2. What is the only possible phenotype for the
offspring?
Talll
You are breeding horses, the gene for a grey horse is dominant to the gene for a
painted horse. And the gene for long haired horse is dominant to the gene for a shorthaired horse. You cross a heterozygous Grey, short-haired horse with a painted
heterozygous long-haired horse. Give the ratios of the phenotypes of the results of the
cross.
Gl
Gl
gl
gl
gL
GgLl
GgLl
ggLl
ggLl
gL
GgLl
GgLl
ggLl
ggLl
Gl
Ggll
Ggll
ggll
ggll
gl
Ggll
Ggll
ggll
ggll
Gray/Long Hair: 4/16 (1:4) (25%)
Painted/Long Hair: 4/16 (1:4) (25%)
Gray/Short Hair: 4/16 (1:4) (25%)
Painted/Short Hair: 4/16 (1:4) (25%)
What is the difference between incomplete dominance and co-dominance? Give an
example of each.
Incomplete dominance is when the heterozygous genotype has its own phenotype, typically a
combination or mixture of the homozygous dominant and homozygous recessive, for example. A straight
haired person (HH) and a curly haired person (hh) would have all heterozygous children, (Hh) and those
children would have wavy hair.
Co-dominance is when you have two or more dominant alleles and they would both be present in the
phenotype. The best example of this would be human blood types. Blood type A and blood type B are
both co-dominant, neither of them ‘win out’ over the other. Blood type O, however, is recessive to both
blood type A and B. Therefore there can be four blood types: Blood Type A (one or more A alleles), Blood
Type B (one or more B alleles), Blood Type O (no A or B alleles), and Blood Type AB (you receive both an
A and a B allele).
Explain who Mendel is and his experiment and how they contributed to science.
Gregor Mendel was an austrian monk in the 1800s who is now considered the ‘father of modern
genetics’. He did experiments with pea plants, by cross-pollinating (basically breeding plants) and he
discovered that there were dominant and recessive traits. That you received traits from both parents and
if you knew which trait was dominant, you could predict the possible phenotypes of the offspring. Also,
you could see recessive traits may not be present in an entire generation and they can reappear in later
generations.