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It’s A Toss Up
1. What do the terms dominant and recessive
mean?
• dominant: the trait observed when at least
one dominant allele for a characteristic is
inherited
• recessive: a trait that is apparent only when
two recessive alleles for the same
characteristic are inherited
It’s A Toss Up
2. Explain the difference between the genotype
and the phenotype of an individual.
• genotype: the genetic makeup of an organism
• phenotype: an organism's appearance or
other detectable characteristic that results
from the organism's genotype and the
environment
It’s A Toss Up
3. How are dominant and recessive genes
written or abbreviated in a genotype?
• The first letter of the word that describes the
dominant trait is capitalized to represent the
dominant trait.
• The same letter is written lowercase to
represent the recessive trait.
It’s A Toss Up
4. How can you tell by looking at the genotype
of the individual if he/she is homozygous or
heterozygous for that trait?
• Having two dominant or two recessive alleles
makes an organism homozygous for that trait.
• Having one dominant & one recessive allele
makes an organism heterozygous for that trait.
It’s A Toss Up
5. Can you tell what someone’s genotype is by
observing their phenotype?
• You can tell if they carry one or none of the
dominant alleles for a trait. You cannot
necessarily tell if they are heterozygous for a
trait, unless there is a third intermediate
characteristic defined by having both a
dominant & recessive allele.
It’s A Toss Up
1. Why is it appropriate for the male parent to
flip for the sex of the offspring?
• The female can only donate an X chromosome
toward the sex of the offspring. It is the male
that determines the sex by donating either an
X or a Y.
It’s A Toss Up
2. What percent chance is there for producing a
male offspring? A female? Explain.
• 50/50
• ½ the gametes carry the X chromosome, the
other ½ carry the Y.
It’s A Toss Up
3. What do the coins represent?
• X or Y chromosome
• Different alleles
It’s A Toss Up
4. What determines the observable physical
characteristics of the offspring?
• the genetic make up (genotype)
It’s A Toss Up
5. Are all three offspring in your group alike?
Would you expect other groups to have
offspring very similar to yours? Explain.
• No
• Because many different alleles for the
thousands of different genes, the likelihood of
having two genetically identical people who
are not twins is improbable.
It’s A Toss Up
6. What are the possible genotypes for the parents
of a child who has wavy hair?
• HH x Hh
• HH x hh
• Hh x HH
• Hh x Hh
• Hh x hh
• hh x HH
• etc.
It’s A Toss Up
7. Which traits in this activity do not show simple
dominance but a blending of traits?
• hair type
• eye size
• eye space
• mouth size
• lip shape
• nose size
• ear size
It’s A Toss Up
8. How would it be possible for the offspring to
show a trait that neither of the parents shows
physically?
• incomplete dominance: HH (curly) x hh
(straight) = Hh (wavy)
• If both parents are heterozygous: Ff (freckles)
x Ff (freckles) = ff (no freckles)