Download 11.2 Applying Mendel`s Principles

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11.2 Applying Mendel’s Principles
1. The chart below shows key terms from the lesson with their meanings. Complete the chart by
writing a definition or example in your own words.
Term
Meaning
Allele
Different form of a gene
Genotype
Genetic makeup
Heterozygous
Organism that has different
alleles for a gene
Homozygous
Organism that has two
identical alleles for a gene
Hybrid
Offspring between parents
with different traits
Independent
assortment
Genes for different traits
segregate independently
when gametes are formed
Phenotype
Physical traits
Principle of
dominance
Some alleles are dominant,
and others are recessive.
Probability
The likelihood that a particular
event will occur
Punnett square
Diagram that can be used to
predict the offspring of a
genetic cross
Segregation
Separation of alleles during
formation of sex cells
Trait
A specific characteristic of an
individual
Definition in your own words
Name
Class
Date
The Experiments of Gregor Mendel
Dominance Mendel’s principle of dominance states that some alleles are dominant and others
are recessive. An organism with a dominant allele will always show the dominant form of the
trait. An organism will only express the recessive form of a trait when a dominant allele is not
present.
In the space provided, fill in the genotype of the offspring. The first one is done for you.
Dominant and Recessive Forms of Pea Plant Traits
Trait
Seed Color
Seed Coat Color
Pod Shape
Parent Plants (P Generation)
Yellow
YY
White
gg
Constricted
ss
X
X
X
Offspring (F1
Generation)
Green
yy
Yellow
Yy
Gray
GG
Gray
Smooth
SS
Smooth
Answer the questions. Circle the correct answer.
1. What is the dominant shape of a pea pod?
constricted
smooth
2. What is the recessive color of a pea plant’s seed coat?
white
gray
BUILD Connections
Not Two of Kind An analogy takes two things that seem to be different and shows how they
can be similar. Visualize a hybrid car. Hybrid cars use two different sources of energy: gasoline
and electricity.
1. A hybrid is a cross, or a mixture, of two things. What is crossed in hybrid cars?
2. Describe one other example of something that is a hybrid:
Probability and Punnett Squares
1. Table A lists some characteristic of pea plants. Write Ph in the right column if the
characteristic describes a phenotype. Write Ge if the characteristic is a genotype.
Table A
Characteristic
Phenotype or Genotype?
tall
short
Tt
TT
yellow seed color
yy
Yy
rr
2. Table B lists some genotypes of pea plants. Write He in the right column if the genotype is
heterozygous. Write Ho if the genotype is homozygous.
Table B
Genotype
RR
tt
Rr
Tt
YY
Yy
Gg
GG
gg
Heterozygous or
Homozygous?
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Probability and Punnett Squares (continued)
In the space provided, fill in the missing genotypes. Write Tt or tt. In this example, T = tall
and t = short.
Tt
T
T
TT
Tt
t
Answer the items.
1. Write the phenotypes of the three genotypes shown above.
TT
________
tt
________
Tt
________
t