Mastering Biology CH 14 homework
Look at the Punnett square, which shows the predicted offspring of the F2 generation from a cross between a plant with yellow-round seeds (YYRR) and a plant with green-wrinkled seeds (yyrr). Select the correct statement about wrinkled yellow seeds in the F2 generation.
The chance that an individual taken at random from the F2 generation produces wrinkled seeds is 25% and the chance that the same individual produces yellow seeds is 75%.
You continue your analysis by crossing the forked and twist lines. Your results are as follows: Which of the following statements best explains the outcome of this cross?
The forked mutation and the twist mutation are codominant alleles of the same locus.
In pea plants, the purple allele is sufficient for making purple flowers, even if one of the homologous chromosomes carries the white allele. Which of the following statements are true in this case? Select all that apply.
The purple allele is the dominant allele. The white allele is the recessive allele. One purple allele results in enough purple pigment for the flowers to be purple.
What was an important limitation in the experiments shown in the video?
There were too few subjects. In other words, the sample size was too small.
Each chromosome in this homologous pair possesses a different allele for flower color. Which statement about this homologous pair of chromosomes is correct?
These homologous chromosomes represent a maternal and a paternal chromosome.
You know that alleles are alternative versions of a gene. What makes alleles different from each other?
They have different sequences of DNA nucleotides.
True or false? The same phenotype can be produced by more than one genotype.
True
The result of the following cross indicates that genotypically the offspring _____.
are all Rr
In the essay, the point is made that perhaps the environment of the children has already guided their preferences in toys BEFORE the experiment was conducted. Given the choices below, what is the earliest age at which environment could potentially shape the preferences of a child?
at age 3 or 4, when children are dressed in gender-specific clothing
In what frequencies would you expect the offspring genotypes? Indicate the frequency of each genotype by dragging the labels to the table. Labels may be used once, more than once, or not at all.
Genotype: I^A^I^B Frequency: 1/4 Genotype: I^A^i Frequency: 1/4 Genotype: I^B^i Frequency: 1/4 Genotype: ii Frequency: 1/4
If an organism with the genotype AaBb produces gametes, what proportion of the gametes would be Bb?
None
In pea plants, the purple allele is sufficient for making purple flowers, even if one of the homologous chromosomes carries the white allele. Which of the following statements are true in this case? Select all that apply.
One purple allele results in enough purple pigment for the flowers to be purple. The purple allele is the dominant allele. The white allele is the recessive allele.
A plant grown from a [round, yellow] seed is crossed with a plant grown from a [wrinkled, yellow] seed. This cross produces four progeny types in the F1: [round, yellow], [wrinkled, yellow], [round, green], and [wrinkled, green]. Use this information to deduce the genotypes of the parent plants. Indicate the genotypes by dragging the correct label to the appropriate location.
Parent genotype with yellow round: RrYy Parent genotype with yellow wrinkled: rrYy
Mendel studied pea plants dihybrid for seed shape (round versus wrinkled) and seed color (yellow versus green). Recall that the round allele (R) is dominant to the wrinkled allele (r) and the yellow allele (Y) is dominant to the green allele (y). The table below shows the F1 progeny that result from selfing four different parent pea plants. Use the phenotypes of the F1 progeny to deduce the genotype and phenotype of each parent plant. Complete the table by dragging the correct label to the appropriate location. Labels can be used once, more than once, or not at all.
Parent phenotype plant 1: green round Parent genotype plant 1: Rryy Parent phenotype plant 2: yellow round Parent genotype plant 2: RrYy Parent phenotype plant 3: yellow round Parent genotype plant 3: RRYy Parent phenotype plant 4: green wrinkled Parent genotype plant 4: rryy
A cross between two individuals that are heterozygous for eye and skin color would be an example of a _____ cross.
dihybrid
The result of the following cross indicates the orange eyes are _____ black eyes.
recessive to
The following question refers to the figure of a family's pedigree chart, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the genotype of individual II-5?
ww
In order to determine the genotype of a MendAlien with black eyes and green skin, you would cross this individual with a(n) _____ individual.
bbgg
What is the genotype of the parent with orange eyes and white skin? (Note: orange eyes are recessive.)
bbgg
A phenotypic ratio of 9:3:3:1 in the offspring of a cross indicates that _____.
both parents are heterozygous for both genes
Which of the following experiments would provide the best data for determining the effect of genetics?
comparing identical twins raised in the same environment with fraternal twins raised in the same environment
----CH 14b homework
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If B represents the allele for black eyes (dominant) and b represents the allele for orange eyes (recessive), what would be the genotypic ratio of a cross between a heterozygous black-eyed MendAlien and an orange-eyed MendAlien?
0 homozygous black (BB): 1 heterozygote (black) (Bb): 1 homozygous orange (bb)
How many variables should there be in a well-designed experiment?
1
In a situation in which genes assort independently, what is the ratio of the gametes produced by an AaBB individual?
1 AB : 1 aB
Two mice are heterozygous for albinism (Aa) . The dominant allele (A) codes for normal pigmentation, and the recessive allele (a) codes for no pigmentation. What percentage of their offspring would have an albino phenotype?
25
What number and types of chromosomes are found in a somatic cell in an animal with a diploid number of 48?
48 chromosomes (24 from each parent, including one sex chromosome from each)
Fraternal twins share _____ of the same genes, while identical twins share _____ of the same genes.
50% on average; 100%
Which of these is a testcross?
A? x aa
What is the difference between heterozygous and homozygous individuals?
All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ.
A botanist has acquired a group of sweet pea plants. All of the plants have yellow pea pods (the recessive trait), except for one, which has green pea pods (the dominant trait). Pea pod color is a trait caused by a single gene. In this tutorial, you will determine how the botanist can identify the genotype of the green pea pod, and how this relates to Mendel's laws and meiosis. How could the botanist best determine whether the genotype of the green-pod plant is homozygous or heterozygous?
Cross the green-pod plant with a yellow-pod plant.
True or false? In diploid organisms, a dominant phenotype will only be expressed if the individual is homozygous dominant for that trait.
False
Select the correct explanation for the fact that a carrier of a recessive genetic disorder does not have the disorder.
In a recessive disorder, only a single functioning allele is necessary to determine a normal phenotype.
A BbGg x bbgg cross yields a phenotypic ratio of approximately 5 black eyes, green skin : 5 orange eyes, white skin : 1 black eyes, white skin : 1 orange eyes, green skin. Which of the following best explains these results?
Mendel's law of independent assortment is being violated.
That each gamete contains a single allele of the eye color gene is an illustration of _____.
Mendel's law of segregation only
The observed distribution of alleles into gametes is an illustration of _____.
Mendel's laws of segregation and independent assortment
Which of the following relationships among alleles of a single gene best explains the observation that a single change in the gene encoding α-keratin results in chickens with frizzled feathers, increased food consumption, higher heart rate and delayed sexual maturity?
Pleiotropy
Which of the following experiments would provide the best data for determining the effect of environment?
comparing identical twins raised in the same environment with identical twins raised in different environments
What genotypes would you expect in future offspring from this marriage? Select all that apply.
ii I^A^i I^B^i I^A^B
Suppose that the botanist carried out the test cross described in Parts A and B and determined that the original green-pod plant was heterozygous (Gg). Which of Mendel's findings does her test cross illustrate?
law of segregation
What is the genotype of the man?
I^A^i
The result of the following cross indicates that the genotype of the female parent is _____.
RR
In the video, the paternal parent carries the allele for purple flowers, and the maternal parent carries the allele for white flowers. What would happen if the maternal parent carried the purple allele, and the paternal parent carried the white allele?
The F1 hybrid pea plants would still produce purple flowers.
If B represents the allele for black eyes (dominant) and b represents the allele for orange eyes (recessive), what would be the phenotypic ratio of a cross between a heterozygous black-eyed MendAlien and an orange-eyed MendAlien?
1 black : 1 orange
Black eyes are dominant to orange eyes, and green skin is dominant to white skin. A male MendAlien with black eyes and green skin, has a parent with orange eyes and white skin. A female MendAlien with orange eyes and white skin. If these male and female MendAliens were to mate, the predicted phenotypic ratio of their offspring would be _____.
1 black eyes, green skin : 1 black eyes, white skin : 1 orange eyes, green skin : 1 orange eyes, white skin
Around the mid-1850s, Mendel crossed true-breeding purple-flowered pea plants with true-breeding white-flowered pea plants. The results of his research provided us with the basic principles of heredity. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.
Every gene is a sequence of DNA nucleotides at a specific position along a chromosome called a locus. Diploid cells have two sets of chromosomes, one set inherited from each parent, that form homologous pairs .The homologs of a chromosome pair contain the same genetic loci. Therefore, each genetic locus is represented twice in a diploid cell. Variations in inherited characteristics is due to the presence of alleles, which are alternative versions of genes.
Around the mid-1850s, Mendel crossed true-breeding purple-flowered pea plants with true-breeding white-flowered pea plants. The results of his research provided us with the basic principles of heredity. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.
Every gene is a sequence of DNA nucleotides at a specific position along a chromosome called a locus. Diploid cells have two sets of chromosomes, one set inherited from each parent, that form homologous pairs. The homologs of a chromosome pair contain the same genetic loci. Therefore, each genetic locus is represented twice in a diploid cell. Variations in inherited characteristics is due to the presence of alleles, which are alternative versions of genes.
For the cross in Part B, predict the frequencies of each of the phenotypes in the F1 progeny, and determine the genotype(s) present in each phenotypic class. Complete the diagram by dragging the correct label to the appropriate location. Labels can be used once, more than once, or not at all.
Expected frequencies yellow round: 3/8 Progeny genotypes yellow round: RrYY, RrYy (x2) Expected frequencies yellow wrinkled: 3/8 Progeny genotypes yellow wrinkled: rrYY, rrYy (x2) Expected frequencies green round: 1/8 Progeny genotypes green round: Rryy Expected frequencies green wrinkled: 1/8 Progeny genotypes green wrinkled: rryy
You decide to designate the twist allele as FT to distinguish it from the forked allele F. Using the following allele symbols, identify the genotypes of the three F2 classes in Part C by dragging one label to each class. Labels may be used once, more than once, or not at all.
F2 twisted: F^T F^T F2 forked: FF F1: FF^T
You continue your genetic analysis by crossing the forked and pale mutant lines with each other. The leaves of the F1 are light green (intermediate between pale and wild-type leaves) and forked. The F2 has six phenotypic classes, as shown below. You designate the forked mutant allele as F (wild type = f+ ) and the pale mutant allele as p (wild type = P). 1. Consider the alleles for leaf color first. Drag the labels to the targets in Group 1 to identify the genotype of each F2 class. Remember that p (the pale mutant allele) and P (the wild-type allele) are incompletely dominant to each other. 2. Consider the alleles for leaf shape next. Drag the labels to the targets in Group 2 to identify the genotype of each F2 class. Remember that F (the forked mutant allele) is dominant to f + (the wild-type allele). Labels may be used once, more than once, or not at all. For help getting started, see the hints.
Group 1 a: PP b: F_ c: Pp d: F_ e: pp f: F_ Group 2 g: PP h: f*f* i: Pp j: f*f* k: pp l: f*f*
Punnett squares are convenient ways to represent the types and frequencies of gametes and progeny in experimental crosses. This Punnett square shows the results of a Yy x Yy cross to form F2 progeny. Use your understanding of Mendel's law of segregation and the rules of probability to complete the Punnett square for this cross. First identify the gametes. Use pink labels to identify the male and female gamete types and white labels to identify the gamete frequencies. Then identify the F2 progeny. Use pink labels to identify the progeny genotypes and white labels to identify the progeny frequencies.
See photo attached for answers
You decide to conduct a genetic analysis of these mutant lines by crossing each with a pure wild-type line. The numbers in the F2 indicate the number of progeny in each phenotypic class. From these results, determine the relationship between the mutant allele and its corresponding wild-type allele in each line. Label each mutant line with the best statement from the list below. Labels may be used once, more than once, or not at all.
Twist: The mutant allele is dominant to its corresponding wild-type allele. Forked: The mutant allele is dominant to its corresponding wild-type allele. Pale: The mutant allele is neither dominant nor completely recessive to its corresponding wild-type allele.
During which part of meiosis (meiosis I or meiosis II) do the two alleles of a gene separate? During which phase does the separation occur? State your answer as meiosis I or meiosis II followed by a comma and the name of the phase (for example, if your answer is meiosis II and metaphase, enter meiosis II, metaphase).
meiosis I, anaphase
An individual heterozygous for eye color, skin color, and number of eyes mates with an individual who is homozygous recessive for all three characters; what would be the expected phenotypic ratio of their offspring? [Hint: B = black eyes, b = orange eyes; G = green skin, g = white skin; C = two eyes, c = one eye]
1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1 black eyes, white skin, one eye : 1 orange eyes, green skin, two eyes : 1 orange eyes, green skin, one eye : 1 orange eyes, white skin, two eyes : 1 orange eyes, white skin, one eye
Use the completed Punnett square in Part B to answer the questions below about the F2 generation. Drag the probabilities on the left to the blanks on the right to answer the questions. Terms can be used once, more than once, or not at all.
1. What is the probability that an F2 seed chosen at random will be yellow? 3/4 2. What is the probability that an F2 seed chosen at random from among the yellow seeds will breed true when selfed? 1/3 3. What is the probability that three F2 seeds chosen at random will include at least one yellow seed? 63/64 4. What is the probability that three F2 seeds chosen at random will include one green seed and two yellow seeds? 27/64
One character in peas that Mendel studied was yellow versus green seeds. A cross between a homozygous yellow line (YY) and a homozygous green line (yy) will result in F1 plants that are heterozygous (Yy) for this trait and produce yellow seeds. When an F1 plant undergoes meiosis, what gamete types will it produce, and in what proportions?
1/2 Y 1/2 y
In the following cross the genotype of the female parent is BbGg. What is the genotype of the male parent? [Hint: B = black eyes, b = orange eyes, G = green skin, g = white skin]
BBGg
What is the genotype of the woman?
I^B^i
Punnett squares can be used to predict the two possible outcomes of the botanist's test cross. The Punnett square on the left shows the predicted result if the unknown plant is homozygous (GG); the Punnett square on the right shows the predicted result if the unknown plant is heterozygous (Gg). Drag the labels to the correct locations on the Punnett squares. (G is the symbol for the green-pod allele and g is the symbol for the yellow-pod allele.) You can use a label once, more than once, or not at all.
Test cross of homozygous green pod plant On top of Punnett square: g Side of Punnett square: G Inside Punnett square: Gg Test cross of heterozygous green pod plant On top of Punnett square: g Side of Punnett square: g Inside Punnett square top row: Gg Inside Punnett square bottom row: gg
When constructing a Punnett square, the symbols on the outside of the boxes represent _______, while those inside the boxes represent _______.
gametes, progeny
What is the genotype of the child?
ii
The result of the following cross indicates that the genotype of the male parent is _____.
rr
In the essay, the point is made that the right questions must be asked when designing an experiment that measures how genetics and environment "shape who we are." Which of the following measurements is probably the least valuable in such an experiment?
the average lifespan
A tall, purple-flowered pea plant (TtPp) is allowed to self-pollinate. (The recessive alleles code for short plants and white flowers.) The phenotypic ratio of the resulting offspring is 9:3:3:1. What is the genotype of the plant whose phenotype appeared once out of every 16 offspring (the "1" in the 9:3:3:1 ratio)?
ttpp
