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MITOSIS: THE AMAZING CELL PROCESS THAT USES DIVISION TO
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Summative assessments:
Visualisation or model of meiosis/mitosis
EVOLUTION
Test - Evolution and Genetics
Lab report – How can evolution be modeled?
AND GENETICS
How does the environment interact with
genes to show variation in organisms and what
are the consequences when genes and/or the
environment changes?
“Man selects only for his own good: Nature
only for that of the being which she tends.”
― Charles Darwin, The Origin of Species
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Table of Contents
Introduction ..............................................................................................2
Part 1 - Evolution ........................................................................................3
Formative assessment – Beak adaptation lab (peer reviewed) ....................................6
Criterion B+C – design your own experiment ...................................................... 10
Part 2 – Meiosis / mitosis ............................................................................. 13
Amoeba Sisters Video Recap of Mitosis .......................................................... 13
Amoeba Sisters Video Recap of Meiosis ............................................................. 15
Part 3 – Genetics ....................................................................................... 17
Monohybrid crossings ............................................................................... 18
Practice monohybrid punnet squares ............................................................ 18
Practice crosses and ratios ........................................................................ 19
Monohybrid Crosses Practice ...................................................................... 21
Codominance and Incomplete Dominance (intermediate) .................................... 25
Practice Problems – Sex Linkage .................................................................. 29
Dihybrid cross........................................................................................ 33
Beyond Mendel – Codominance, Multiple Alleles, and Polygenic Traits ................. 37
Pedigree .............................................................................................. 39
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Introduction
In the following weeks we are going to explore the evolution theory and genetics to
understand the inquiry; “How did we evolve into the species we are now”. In order for us
to answer this question we need understanding in evolution and genetics and the
mechanisms involved.
Part one will consist of several experiments and other investigations to understand the
concept natural selection, the driving force behind evolution. You will investigate Darwin
and his theory and how it changed to the widely accepted theory we are using today.
Part two will give a brief introduction into meiosis (and mitosis) as this is important in
understanding how DNA is passed on to our offspring and how meiosis accounts for
variation.
Part three will zoom in on genetics. You will understand how the variations occurring
through natural selection are passed on to offspring and how they find a way in the
population.
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AMOEBA SISTERS: VIDEO RECAP
Part 1 - Evolution
1. What is meant by the term adaptation?
2. Name one animal and one plant with which you are familiar, and describe how each is
adapted to its environment.
3. Using only the following information, answer questions A to D.
Cepaea is a type of snail which shows considerable variation in its shell colour. The basic
colour can be yellow, brown, fawn, pink, orange or red. Over the top of this basic colour
up to five bands of a darker colour may occur, around the shell. Colour of shell provides
camouflage for the snail because some colours are more difficult to see than others against
the background.
Cepaea is an important part of the diet of thrushes. These birds collect snails and break
open their shells by banging them on a stone. Thrushes tend to use the same stone, called
an ‘anvil’ , whenever feeding in a particular area.
It is possible to collect the remains of the shells and count the number of each shell type.
It is also possible to collect the live snails in the same area and count the numbers of each
shell type.
Collections of both live snails and broken shells were made in an area where the ground
layer plants gave a fairly evenly coloured background. The results are shown in the table.
Live snails
Shell remains
Banded
264
486
Number
Unbanded
296
377
of snails
Total
560
863
% Banded
47.0
56.0
a) How many more live, unbanded Cepeae were collected than banded?
b) Suggest an explanation for thrushes taking more banded snails even where there
appear to be more unbanded snails in the live populations.
c) Which type of shell, banded or unbanded, would you expect to occur most
frequently in a live snail population
i.
Amongst dead leaves in a wood?
ii.
Amongst grasses growing on a sand dune?
d) The main points of the theory of evolution by natural selection are listed below
A
The number of offspring is far greater than the number surviving to adult
stage
B
Variations exist among the offspring
C
Some variations are useful and help the organisms to survive
D
Competition occurs between the offspring
E
Only those surviving can breed
Natural selection can change the proportions of the different colours in a
snail population. Use the five points A to E above to describe how this
change might come
about.
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AMOEBA SISTERS: VIDEO RECAP
Amoeba Sisters Video Recap: Natural Selection
1. Populations can have variety, despite being made up of
the same species. If a population has different expressed
traits, this can be due to different inherited alleles. The
frogs below are the same species, but they have different
shades of green based on their inherited alleles. In a
particular environment, lighter green frogs are easier to see
by predators. Explain how natural selection could lead to a
change in allele frequency.
2. Natural selection is an example of a mechanism of
evolution. Does this mechanism produce a change in
individuals or populations? Explain!
3. A major point of understanding natural selection is that not all
organisms in a population get to reproduce. Consider the term fitness as
used in biology. How does this term relate to natural selection?
4. Based on your answer above, do organisms with higher fitness mean that they have survived to an advanced age? Why
or why not?
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5. Does fitness (as used in biology) and survival have the same meaning? Why or why not?
6. If an organism has high biological fitness in one environment, does that mean that it would also have high biological
fitness in another environment? Why or why not?
7. Two students are discussing natural selection in bacteria and how it can relate to antibiotic
resistance in bacteria.
Bernadette states that when antibiotics are used, bacteria can respond by developing traits to
help them defeat the antibiotic, which then may increase their fitness.
Dominique states that there is already a variety of traits among the bacteria. Bacteria that have traits
that allow them to survive the antibiotic and reproduce may have higher fitness.
Which individual's reasoning do you agree with more and why?
8. A major misconception about natural selection is that this mechanism “gives organisms what they want or need so they
can adapt to an environment.” Explain why this is not correct.
9. Consider a major environmental change. If there are not organisms in a population that have traits that allow them to
still continue to survive to reproduce, what would likely happen to that population?
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Formative assessment – Beak adaptation lab (peer reviewed)
Problem statement: you are going to mimic how the variations of Darwin’s finches
compete for the same food sources. Pretend that the brown coloured beans are seeds for
the birds. Natural selection happens when a population changes in response to their
environment.
Hypothesis: If I had the ___________________ adaptation, then I would be the most fit for
survival in the grass environment.
Materials and procedure: explained by teacher
Data:
Beans
brown
Knife
Spoon
1st generation
Fork
Taped
Hand
Total
-100=
Beans
brown
Knife
Spoon
2nd generation
Fork
Taped
Hand
Total
-100=
Beans
brown
Knife
Spoon
3rd generation
Fork
Taped
Hand
Total
-100=
Beans
brown
Knife
Spoon
4th generation
Fork
Taped
Hand
Total
-100=
Graphing:
Create one line graph with the generation on the x-axis and the total number of beans on
the y-axis. Use a legend and colored pencils to graph all five of the five-beaked
adaptations
Analysis:
1) Independent variable:_________________________________________________
Dependent variable: _________________________________________________
Controlled variables: _________________________________________________
2) Which finch became extinct first and explain why it was not the best adapted for
survival?
________________________________________________________________________
________________________________________________________________________
3) Which finch was best adapted for survival? ___________________________________
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4) Why was the brown beans (seeds) well adapted in the grass environment?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
5) If white or red beans (seeds) were introduced into the grass, which seeds would you
think would be eaten the most?____________________ Explain why?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
6) Would the length of the grass affect which adaptation was better suited for the
collecting beans? If so, explain which adaptation would most be affected for short
or long grass.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
7) In this lab we had only one environment, the ___________________. Four
adaptations became extinct in that environment, but on the Galapagos islands,
there were many surviving species of finches. How might the finches in this lab
avoid extinction due to competition?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
8) Conclusion: explain about how natural selection leads to adaptation of populations
using the following terms: population, environment, competition, fittest,
adaptation and selection.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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Peer review
You will grade each other’s work in pairs according to the following procedure
1. You form a group of 3
2. You will check each other’s work in a rotation set up and you will award points to
each question, use the table below to see how many points you can award each
question
Question
# points to be awarded
Graph
1 point for a correct title (1/2 point also possible for a title)
1 point for labelling both y AND x-axis (1/2 point for 1)
1 point for correct values (scale)
1 point for a completed graph with all 5 lines
1 point for a correct legend
Q1
2 points (-1 for each mistake, 0 points with only 1 correct
answer)
Q2
2 points (depending on explanation)
Q3
1 point
Q4
2 points (depending on explanation)
Q5
2 points (depending on explanation)
Q6
2 points (depending on explanation)
Q7
2 points (depending on explanation)
Q8
6 points, check if all mentioned words are used in the
correct way. Each correctly used/explained word in relation
to the question will count as 1 point
3.
You will use a premade format (next page) to fill in the points given to your peers,
after you have checked both you will discuss in your group a final decision on how
many points may be awarded for each answer. This is called standardizing and it
ensures that a fair grade can be given.
4. The given grade will appear on managebac as a formative grade, teacher will
randomly select a couple graded papers to standardize further.
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Peer review format
Name of person who is being graded:_____________________________
Peer review 1 done by: _______________________________
Peer review 2 done by: _______________________________
Question
#points given by
peer reviewer 1
#points given by
peer reviewer 2
Final decision
#points
Graph
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Total
Comments by peer reviewer 1:
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Comments by peer reviewer 2:
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
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Criterion B+C – design your own experiment
In the Finch adaptions lab we have seen how natural selection works in regards with food
sources and how natural selection in turn leads to adaptation of populations. This one was
about the beak of the birds. You are now going to design your own experiment about
natural selection specified on the importance of coloration. How did evolution give
certain animals their specific colour? And how can you show with an experiment that
certain coloured animals would have a really hard time surviving?
-
Individual assignment
Include ALL parts of a lab report
Experiment will be conducted!
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AMOEBA SISTERS: VIDEO RECAP
Achievement
level
0
1-2
Level descriptor B
The student does not reach a standard described by any of the descriptors
below.
The student is able to:




3-4
The student is able to:




5-6
outline a problem or question to be tested by a scientific
investigation
formulate a testable hypothesis using scientific reasoning
outline how to manipulate the variables, and outline how relevant
data will be collected
design a safe method in which he/she selects material and
equipment
The student is able to:




7-8
state a problem or question to be tested by a scientific investigation
outline a testable hypothesis
outline the variables
design a method, with limited success
describe a problem or question to be tested by a scientific
investigation
formulate and explain a testable hypothesis using scientific
reasoning
describe how to manipulate the variables, and describe how
sufficient, relevant data will be collected
design a complete and safe method in which he/she selects
appropriate material and equipment
The student is able to:




explain a problem or question to be tested by a scientific
investigation
formulate and explain a testable hypothesis using correct
scientific reasoning
explain how to manipulate the variables, and explain how
sufficient, relevant data will be collected
design a logical, complete and safe method in which he/she
selects appropriate material and equipment
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AMOEBA SISTERS: VIDEO RECAP
Achievement
level
0
1-2
Level descriptor C
The student does not reach a standard described by any of the descriptors
below.
The student is able to:





3-4
The student is able to:





5-6
correctly collect and present data in numerical and/or visual
forms
accurately interpret data and explain results
outline the validity of a hypothesis based on the outcome of a
scientific investigation
outline the validity of the method based on the outcome of a
scientific investigation
outline improvements or extensions to the method
The student is able to:





7-8
collect and present data in numerical and/or visual forms
interpret data
state the validity of a hypothesis based on the outcome of a
scientific investigation
state the validity of the method based on the outcome of a
scientific investigation
state improvements or extensions to the method
correctly collect, organize and present data in numerical and/or
visual forms
accurately interpret data and explain results using scientific
reasoning
discuss the validity of a hypothesis based on the outcome of a
scientific investigation
discuss the validity of the method based on the outcome of a
scientific investigation
describe improvements or extensions to the method that would
benefit the scientific investigation
The student is able to:





correctly collect, organize, transform and present data in
numerical and/or visual forms
accurately interpret data and explain results using correct
scientific reasoning
evaluate the validity of a hypothesis based on the outcome of a
scientific investigation
evaluate the validity of the method based on the outcome of a
scientific investigation
explain improvements or extensions to the method that would
benefit the scientific investigation
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AMOEBA SISTERS: VIDEO RECAP
Part 2 – Meiosis / mitosis
Amoeba Sisters Video Recap of Mitosis: The Amazing Cell Process That Uses
Division to Multiply
1.
Mitosis is done by your body
cells. What types of cells do not
undergo mitosis?
2.
Describe 2 ways that mitosis is
important for your body.
3.
This illustration is trying to
demonstrate something that
mitosis is not. In mitosis, the
cells that are created
are
4.
Mitosis is just one small part of
the cell cycle! Describe what
would occur if cells were in
mitosis more than they were in
interphase.
5.
When cells are dividing, it is
important to understand that
they have to move
chromosomes equally to both
cells. Based on this illustration,
describe what a chromosome is
made of.
6.
Mitosis starts and ends with
diploid cells. That means they
have two sets of chromosomes
(both parents each contribute a
set). In humans, how many
chromosomes should be in each
of these diploid cells after
mitosis?
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Sketch the Mitotic Stages
Directions: We encourage you to be creative with a cartoon illustration of your own for each phase. Label the
chromosomes, spindles, and nucleus (if applicable).
Prophase
Metaphase
Anaphase
Telophase
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Amoeba Sisters Video Recap of Meiosis
1. The purpose of meiosis is to make
gametes, also known as sperm and egg
cells. In humans, your body cells have 46
chromosomes. How many chromosomes
are in a sperm or egg cell if, when they
come together to form a fertilized zygote,
there are 46 chromosomes? Write the
correct number of chromosomes next to
the sperm and egg.
2. Interphase must occur once before
meiosis can happen. (Same thing for
mitosis). What would happen if
interphase didn’t occur first?
3. A cell that begins meiosis has 23
chromosomes inherited from the mother
(shown in green in the cartoon below)
and 23 chromosomes inherited from the
father (shown in blue in the cartoon
below). In the process of meiosis,
chromosomes begin to match up in
homologous pairs. How would you know
if two chromosomes were homologous?
4. Crossing over is a very important event
in Prophase I of meiosis! What happens
during crossing over and what is the
significance?
5. Meiosis does PMAT twice! That
means there is a prophase I and a
prophase II. There is a metaphase I and
a metaphase II. Etc… If the cartoon
below has chromosomes in the middle
of the cell, how would you know
whether it was in metaphase I or
metaphase II?
6. Meiosis does not always occur
without any difficulties. Describe what
occurs during nondisjunction and the
effect on the resulting cells.
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AMOEBA SISTERS: VIDEO RECAP
Can you finish the meiosis chain? Write the correct stage that comes next in each circle. Don’t forget
the number that comes after the stage name! Then write any details about what this stage looks
like next to it.
Now let’s play, “Which Clip Would That Be Said In?”
Keeping mitosis and meiosis separate in your mind can be a bit tricky. Read the following speech bubbles. Determine whether
they would be correctly placed in the mitosis clip, the meiosis clip, or both by drawing a line to the correct place in the Venn
diagram.
Interphase
occurs once
before the
process
begins.
Process
ends with
identical
cells.
Produces
gametes
Produces 4 cells
that each have
23
chromosomes.
Crossing
over
occurs
Process is
important
for growth
and repair
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Part 3 – Genetics
1. Use examples to explain the difference between continuous and discontinuous
variation
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
2.
a) Explain the term mutation
_____________________________________________________________________
_____________________________________________________________________
b) State two examples of mutation in humans
_____________________________________________________________________
_____________________________________________________________________
c) Explain why genetic variation is important
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
3. Explain the difference between genotype and phenotype
________________________________________________________________________
________________________________________________________________________
4. Explain the difference between gene and allele
________________________________________________________________________
________________________________________________________________________
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Monohybrid crossings
Practice monohybrid punnet squares
Use your knowledge of genes and inheritance to determine the probability of any offspring of
these superheroes having their powers (mutated genes).
Write down the ratios and the percentage of chances of having the specific ability.
h = allele for the power to heal f = allele ability to fly
m = allele for mind reading powers s = allele for super strength
l =allele for laser eyes o = allele for the ability to control the weather
w = allele for the ability to climb up walls
Remember: Mutated genes are recessive
For each match and each superpower figure out the probability of inheriting that
superpower
Jean Grey
Hh
ff
Wolverine
X
hh
Ff
mm
MM
Ss
ss
Rogue
ff
Ss
LL
Superman
ff
X
Storm
ss
ll
ff
Cyclops
FF
LL
ll
oo
X
OO
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Practice crosses and ratios
1. a) Brown eye colour is dominant. If a woman is homozygous for
brown eyes, what is her genotype going to be?
(BB, Bb or bb)
b) Blue eye colour is recessive on the same Allele as Brown eyes.
If a man has blue eyes, he must be homozygous. What is his
genotype?
(BB, Bb or bb)
c) The woman from part a, and the man from part b have a child.
Fill in this punnett square. In the grey squares you should put the
Alleles of the mother and father.
Mother
Father
d) What is the fraction ( __/4) of Brown eyed children?
e) What is the ratio? ___________
2. A flower arranger is growing some flowers in a garden. He has
seeds for red, and seeds for pink plants. Both colours are found
on the same allele as each other. Red is the dominant colour,
while pink is recessive.
a) Using the letter R, what are the possible Genotypes for the red
coloured flower? ____________________________________
b) What is the genotype for the pink flower? _________________
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c) Because homozygous dominant and heterozygous are both red,
the farmer wants to know which one he has. He crosses the red
and the pink seeds and lets them grow. Half of them are pink
and half are red. Were the red seeds homozygous dominant, or
heterozygous?
3. A man is a carrier for sickle cell disease. He does not suffer from
the disease. This disease means that blood cells do not form in
the proper shape. The disease affects only in the heterozygous
recessive state.
a) Using the letter S, what is the genotype for the male carrier?
b) The man has a child with a woman who is also a carrier for the
disease. Draw a punnett square in the space below for the
possibilities of offspring genotypes.
c) What is the ratio of children that have the disease? ________
d) What is the ration of children that are carriers of the disease?
________
e) Is there a chance that they could have a child that is neither a
carrier nor a sufferer? __________
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MITOSIS: THE AMAZING CELL PROCESS THAT USES DIVISION TO
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Monohybrid Crosses Practice
For all of the following questions, use these facts: the trait is fur color (f). Black fur is
dominant over gray fur.
a) Write the letter of the dominant allele. _________
b) Write the letter of the recessive allele. _________
c) Write out the homozygous dominant genotype (2 alleles). _________
d) Write out the heterozygous genotype (2 alleles). _________
e) Write out the homozygous recessive genotype. _________
f) Write the genotype for gray fur. _________
g) Write the genotype for Black fur. _________ or _________
h) Write the phenotype for #3. _________________________
i) Write the phenotype for #4. _________________________
j) Write the phenotype for #5. _________________________
Still using fur color, do the following monohybrid cross problems. (Remember: Black
fur is dominant over gray)
If the mother is homozygous recessive and the father is
homozygous dominant.
a) Write the genotype probabilities.
b) Write the phenotype probabilities.
If the mother is heterozygous, and the father is
heterozygous.
a) Write the genotype probabilities.
b) Write the phenotype probabilities.
If the mother is heterozygous, and the father is
homozygous dominant.
a)Write the genotype probabilities.
b) Write the phenotype probabilities.
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AMOEBA SISTERS: VIDEO RECAP
If the mother is homozygous recessive, and the father is
heterozygous.
a) Write the genotype probabilities.
b) Write the phenotype probabilities.
Word Problems using Monohybrid Crosses
1. Purple flowers (P) are dominant to white flowers (p). Perform the following crosses. For
each cross, give the phenotype and genotype of all offspring.
A. PP x pp
B. Pp x Pp
C. PP x Pp
2. In pea plants, yellow seed color is dominant to green seed color. If a heterozygous pea
plant is crossed with a plant that is homozygous recessive for seed color, what is the
probability that the offspring will have green seeds?
3. If all of the offspring of a particular cross have the genotype Gg, what must the
genotype of the parents be?
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MITOSIS: THE AMAZING CELL PROCESS THAT USES DIVISION TO
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4. In fruit flies normal wings (W) is dominant over vestigial wings (w). The results of a
cross, of
two fruit flies, give the following results:
Normal wing 793
Vestigial wing 811
What are the genotypes of the parents of the F1 generation offspring? Use a Punnett
square
to prove your answer.
5. Red eyes (R) in fruit flies are dominant over white eyes (r). Using Punnett squares, find
the
possible eye colors of the F1 generation for each of the following crosses.
A. Rr x rr
B. rr x RR
C. Rr x Rr
6. The result of a cross is 3 purple flowers and 1 white flower. Using a cross, determine
whether a plant with purple flowers is heterozygous (Pp) or homozygous dominant (PP).
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MITOSIS: THE AMAZING CELL PROCESS THAT USES DIVISION TO
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Practice with Crosses. Show all work!
5. A TT (tall) plant is crossed with a tt (short plant).
What percentage of the offspring will be tall? ___________
6. A Tt plant is crossed with a Tt plant.
What percentage of the offspring will be short? ______
7. A heterozygous round seeded plant (Rr) is crossed with a
homozygous round seeded plant (RR).
What percentage of the offspring will be homozygous (RR)? ____________
8. A homozygous round seeded plant is crossed with a homozygous
wrinkled seeded plant. What are the genotypes of the parents?
__________ x __________
What percentage of the offspring will also be homozygous?
______________
9. In pea plants purple flowers are dominant to white flowers.
If two white flowered plants are cross, what percentage of their
offspring will be white flowered? ______________
10. A white flowered plant is crossed with a plant that is
heterozygous for the trait. What percentage of the
offspring will have purple flowers? _____________
11. Two plants, both heterozygous for the gene that controls
flower color are crossed. What percentage of their offspring
will have purple flowers? ______________
What percentage will have white flowers? ___________
12. In guinea pigs, the allele for short hair is dominant.
What genotype would a heterozygous short haired guinea pig have?
_______
What genotype would a purebreeding short haired guinea pig have?
_______
What genotype would a long haired guinea pig have? ________
13. Show the cross for a pure breeding short haired guinea pig
and a long haired guinea pig.
What percentage of the offspring will have short hair? __________
14. Show the cross for two heterozygous guinea pigs.
What percentage of the offspring will have short hair? ________
What percentage of the offspring will have long hair? _______
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Codominance and Incomplete Dominance (intermediate)
1. Practice setting up keys for the phenotypes
listed in each set. Remember that the
"medium" trait must always be heterozygous.
a) Birds can be blue, white, or white with bluetipped feathers.
b) Flowers can be white, pink, or red.
c) A Hoo can have curly hair, spiked hair, or a
mix of both curly and spiked.
d) A Sneech can be tall, medium, or short.
e) A Bleexo can be spotted, black, or white.
2. Now, can you figure out in the above list, which of the letters represent
codominant traits and which are incomplete.
Codominant _____________ Incompletely Dominant ________________
3. In Smileys, eye shape can be starred, circular, or a circle with a star.
Write the genotypes for the pictured phenotypes
4. Show the cross between a star-eyed and a circle eyed.
What are the phenotypes of the offspring? ____________
What are the genotypes? __________
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5. Show the cross between a circle-star eyed, and a circle eyed.
How many of the offspring are circle-eyed? ____________
How many of the offspring are circle-star eyed? ____________
6. Show the cross between two circle-star eyed.
How many of the offspring are circle-eyed? ____________
How many of the offspring are circle-star eyed? ____________
How many are star eyed? ____________
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Incomplete dominance
1. In snapdragons, flower color is controlled by incomplete dominance. The
two alleles are red (R) and white (W). The heterozygous genotype is
expressed as pink (RW)
a. What is the phenotype of a plant with the genotype RR? ___________
b. What is the phenotype of a plant with the genotype WW? ___________
c. What is the phenotype of a plant with the genotype RW? __________
2. Predict the offspring when two pink Four o’clock flowers (RW) are crossed.
a. What is the predicted genotypic ratio for the offspring?
b. What is the predicted phenotypic ratio for the offspring?
3. A pink-flowered plant is crossed with a white-flowered plant. What is the
probability of producing
a. A pink-flowered plant?
______________
b. A red flowered plant?
_______________
c. A white flowered plant?
________________
D . What cross will produce the most pink-flowered plants? Show a
punnett square to support your answer.
4. A homozygous black bird is crossed with a homozygous white bird. The
offspring are all bluish-gray.
Cross a black bird and a bluish gray bird. What are the genotypic ratios and
percent chance of each phenotype?
4. What results if a white individual is crossed with a bluish-gray individual?
(SHOW YOUR WORK)
6. If two bluish-gray individuals were crossed, what would be the ratios for both
phenotype and genotype of the offspring?
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Codominance
1. In a certain fish, blue scales and red scales are
codominant. What happens if you breed a
patchwork fish with a fish that only has blue
scales?
Step 1: determine the genotypes of the
parents
Step 2: set up the punnet square
Step 3: count the number of each phenotype
2. What is the phenotypic and genotypic ratio
when you cross two patchwork fish?
3. In some chickens, the gene for feather color is controlled by codominance. The
allele for black is B and the allele for white is W. The heterozygous phenotype is
known as erminette (black and white spotted).
a) What is the genotype for black chickens? ___________
b) What is the genotype for white chickens? ____________
c) What is the genotype for erminette chickens? __________
4. Two erminette chickens were crossed. Show the punnet square
a) What is the probability they would have a black chick?
b) What is the probability they would have a white chick?
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Practice Problems – Sex Linkage
1. Coat color in cats is a codominant trait and is also located on the X
chromosome. Cats can be black, orange or calico. A calico cat has
black and orange splotches. In order to be calico, the cat must have an
allele for the black color and an allele for the orange color. Use a
Punnett square to show why there are no male calico cats.
2. A female calico cat is crossed with a male black cat. What are the phenotypes of the offspring and
in what proportion?
3. In humans, Duchenne muscular dystrophy (DMD) is a disease where muscles become weaker
over time. The gene is located on the X chromosome and is recessive. Those afflicted with this
disease usually die in childhood. If a female is a carrier for DMD, what percentage of her sons will
inherit the disease? What percentage of her daughters will inherit the disease.
4. Eye color in fruit flies is sex linked, with the recessive allele causing white eyes. Show the cross for
a white eyed female and a red-eyed male. How many offspring will have white eyes and what is
their sex?
5. Show the reciprocal cross: A red eyed female (homozygous) and white eyed male. How many
offspring will have white eyes and what is their sex?
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5. In humans, color blindness is sex linked and recessive. If a woman is colorblind, what
percentage of her sons will also be colorblind?
Sex linkage – fruit flies
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Dihybrid cross
In rabbits, grey hair is dominant to white hair.
Also in rabbits, black eyes are dominant to red eyes.
GG = gray hair
Gg = gray hair
gg = white hair
BB = black eyes
Bb = black eyes
bb = red eyes
1. What are the phenotypes (descriptions) of rabbits that have the following
genotypes:
Ggbb ____________________ ggBB ________________________
ggbb ____________________ GgBb _________________________
2. A male rabbit with the genotype GGbb is crossed with a female rabbit
with the genotype ggBb The square is set up below. Fill it out and
determine the phenotypes and proportions in the offspring.
How many out of 16 have grey
fur and black eyes? ______
How many out of 16 have grey
fur and red eyes? ________
How many out of 16 have white
fur and black eyes? ______
How many out of 16 have white
fur and red eyes? _______
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3. A male rabbit with the genotype GgBb . Determine the gametes
produced by this rabbit
(the sperm would have these combinations of alleles) Hint there are 4
combinations.
4. Use the gametes from #3 to set up the punnet square below. Put the
male's gametes on the top and the female's gametes down the side. Then
fill out the square and determine what kind of offspring would be produced
from this cross and in what proportion. Use a blank page for more room.
5. An aquatic arthropod called a Cyclops has
antennae that are either smooth or barbed. The allele
for barbs is dominant. In the same organism,
resistance to pesticides is a recessive trait. Make a
"key" to show all the possible genotypes (and
phenotypes) of this organism. Use the rabbit key to
help you if you're lost.
6. A Cyclops that is resistant to pesticides and has smooth antennae is
crossed with one that is heterozygous for both traits. Show the genotypes of
the parents. ______________ x _______________
7. Set up a punnet square for the cross and show the phenotypic ratios.
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Beyond Mendel – Codominance, Multiple Alleles, and
Polygenic Traits
1. In a certain cactus, prickly spines can be two pronged or one pronged. If
a true breeding one-pronged cactus is crossed with a true breeding twopronged cactus, the F1 generation has a mixture of spines, some are twopronged, some are one-pronged.
a. Is this an example of codominance or incomplete dominance?
b. Show the F2 generation (a cross between the two F1's). What are the
phenotypes of the offspring and in what proportion?
2. In this same cactus, if you cross a plant that has red flowers to one that
has yellow flowers, you produce a plant that has orange flowers. Is this
codominance or incomplete dominance? Show the cross of an orange
flowered plant to a red flowered plant.
3. A red flowered, two-pronged cactus is crossed with a yellow flowered
one-pronged cactus. What are the resulting offspring and in what
proportion?
4. Show the cross of a cactus that is heterozygous for both traits crossed
with one that has red flowers and one-pronged spikes.
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5. A man with type A blood is married to a woman with type O blood. What
are ALL of the possible blood types of their children.
6. A man with type AB blood is married to a woman with type O
blood. What are all the possible blood types of their children?
7. A man with type A blood whose mother was type O is married to a
woman with type AB blood. What are the blood types of their children and in
what proportion?
8. In Snarlymonsters, the number of teeth is polygenic. The recessive
condition (aabbcc) results in a toothless Snarlymonster, and the dominant
condition (AABBCC) results in a Snarlymonster with 6 teeth. There are 5
other possible variations.
How many teeth would a AaBbCc Snarlymonster have? ______
How many would a AABBcc Snarlymonster have? ______
How many would a aaBbcc Snarlymonster have? ______
9. List the phenotypic ratios (how many teeth) of all the potential offspring
for the cross AABBCc x AAbbcc .
10. List the phenotypic ratios (how many teeth) of all the potential offspring
for the cross aaBbCc x AAbbcc .
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Pedigree
1. Susan is a carrier of sickle cell disease. She is married to Ivan who is
also a carrier. Susan’s father, Stewart, was also a carrier of the
disease, but her mother, Ruth, did not. Susan has a brother called
James who is not a carrier.
Ivan has two sisters who are also carriers. His mother Rachel suffers
from the disease but his father Richard does not.
Susan and Ivan have two sons. Jack has sickle cell disease, but his
brother, Robert, does not.
Put the names of the family onto the pedigree chart below.
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