Inquiry Activity

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Inquiry Activity
Section 15-1

• 1. Hypothesis What kind of variation in length
  do lima beans show?
• Prediction ____________________________________
• Data Gathering
• With your partner, count out 10 lima beans and
  measure the length of each to the nearest 0.5
  millimeter. Record your results in a data table.
  Graph the number of lima beans you found at each
  length, and draw a best-fit curve for your data.
• (see sample data)
• Add another lab pairs data to your data table,
  graphing the combined data on the same graph as
  your original data, and draw a new curve.
• (see sample data)
• Repeat Step b until you have drawn a curve
  representing the combined data of the class.

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• Analyzing the Data As more and more data is
  added, how long
• are most
  of the beans measured?
• 5. Drawing Conclusions ________________________
  _________
• _________________________________
• _________________________________

most lima beans are medium-sized
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So why are most lima beans, and other
sexually-reproducing organisms, medium-sized?
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An individual who produces as much melanin as
humanly possible has genotype MMLLNN. That
persons phenotype would be to have very dark
skin, so brown as to almost appear black.
MMLLNN
During meiosis, the diploid (2n) genotype,
MMLLNN, Is reduced to the haploid genotype. As
the alleles are segregated from each other, the
only possibility for the sperm or egg is MLN.
MLN
MLN
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The union of one genetic half-cell, the sperm,
with the other genetic half-cell, the egg,
results in one genetically whole cell, the
zygote
MLN
sperm

MMLLNN
zygote
fertilization
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Add the alleles from the sperm (MLN) and the
alleles from the egg (MLN) to determine the
genotype of the zygote (and the new individual),
(MMLLNN)
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The genotype of all the offspring, (1 out of 1,
or 1/1), is MMLLNN, so all the offspring have the
same phenotypevery dark skin.
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An individual who produces as little melanin as
humanly possible has genotype mmllnn. That
persons phenotype would be to have very light
skin, so as to appear so white that the pink of
the blood shows through.
mmllnn
mln
mln
During meiosis, the diploid (2n) genotype,
mmllnn, is reduced to the haploid genotype. As
the alleles are segregated from each other, the
only possibility for the sperm or egg is mln.
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Add the alleles from the sperm (mln) and the
alleles from the egg (mln) to determine the
genotype of the zygote (and the new individual)
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The genotype of all the offspring, (1 out of 1,
or 1/1), is mmllnn, so all the offspring have the
same phenotypevery light skin.
In both examples, when the very dark mate with
the very dark and when the very light mate with
the very light, the crosses result in no
variation.
What happens if the very dark mate with the very
light?
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Add the alleles from the sperm (MLN) and the
alleles from the egg (mln) to determine the
genotype of the zygote (and the new individual)
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The genotype of all the offspring, (1 out of 1,
or 1/1), is MmLlNn, so all the offspring have the
same phenotypemedium skin.
In all three examples, when the very extreme mate
with the very extreme, the crosses result in no
variation.
What happens if the medium-skinned mate with the
medium skinned?
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During meiosis, the diploid (2n) genotype,
MmLlNn is reduced to the haploid genotype. As
the alleles segregate and assort independently,
maximum diversity results.
MLN
mln
MLn
mlN
MmLlNn
MlN
mLn
Mln
mLN
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Add the alleles from the sperm (MLN) and the
alleles from the egg (MLN) to determine the
genotype of the zygote (and the new individual),
(MMLLNN)
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Now do the same for the other possible
combinations of sperm and eggs, filling in the
boxes of the Punnet square
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Now, fill in the rest of the squares
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If you count up the number of alleles represented
by capital letters, you get the number of alleles
that code to make a persons hair, eyes, or skin
darker, because each allele represented by a
capital letter causes skin cells to make more
melanin (brown pigment)
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The number of alleles coding for the cells to
make melanin determine how genetically dark the
individuals hair, skin, or eyes will be. Count
up the alleles and total them in the first square
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The number of alleles coding for the cells to
make melanin determine how genetically dark the
individuals hair, skin, or eyes will be. Count
up the alleles and total them in the first square
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Now, count up the alleles coding for melanin
production and total them in each square of the
Punnet square
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Now, count up the alleles coding for melanin
production and total them in each square of the
Punnet square
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Now, fill in the rest of the squares in the
Punnet square. Notice there is a pattern to the
numbers.
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Count how many sixes, fives, fours, threes, twos,
ones, and zeroes, out of 64, and write the totals
in the data table on the next slide.
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Now, plot the data on the graph, with the numbers
of alleles on the x-axis and the number of
individuals on the y-axis.
1
6
15
20
15
6
1