Biology Exam 3
Imagine a locus with four different alleles for fur color in an animal. The alleles are named Da, Db, Dc, and Dd. If you crossed two heterozygotes, DaDb and DcDd, what genotype proportions would you expect in the offspring?
25% DaDc, 25% DaDd, 25% DbDc, 25% DbDd
Given the following genotypes for two parents, AABBCc × AabbCc, assume that all traits exhibit simple dominance and independent assortment. What proportion of the progeny of this cross will be expected to phenotypically resemble the first parent with the genotype AABBCc?
3/4
Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a woman and her husband are both carriers, what is the probability that their first child will be a phenotypically normal girl?
3/8
Quaking aspen trees can send out underground stems for asexual reproduction. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?
38
Skin color in a certain species of fish is inherited by a single gene with four different alleles. How many different types of gametes would be possible in this organism?
4
Nucleic acids are assembled in the _____ direction.
5' to 3' New nucleotides are added to the 3' end of a growing polynucleotide.
Given a template strand of 3'-ATGCTTGGACA-5' and a partially-made complementary strand containing only 5'-TAC-3', what would be the sequence of the new strand of DNA (including the 5'-TAC-3') if the only additional nucleotides available to DNA polymerase were those containing the bases G, A, and C?
5'-TACGAACC-3' DNA polymerase will continue to add nucleotides onto the growing strand as long as it has nucleotides with the bases required to complement the template strand. If it is missing one kind of base, it will stop at that point on the strand.
How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
8
Duplication of chromosomes occurs during S phase of the cell cycle. Duplication requires the separation of complementary DNA strands to allow for DNA replication. Which of the following statements best explains how weak hydrogen bonds function better in this situation than stronger bonds would?
Complementary DNA strands are separated or "unzipped" for the replication process. Weak hydrogen bonds between complementary strands are easily disrupted during DNA replication because they are not high-energy chemical bonds.
Nearly every mRNA gene that codes for a protein begins with the start codon, _____, and thus begins with a methionine. Nearly every protein-coding sequence ends with one of the three stop codons (UAA, UAG, and UGA), which do not code for amino acids but signal the end of translation.
AUG
A black guinea pig crossed with a guinea pig with albinism produced 12 black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?
Albinism is a recessive trait; black is a dominant trait.
Now, suppose that the three tomato genes from Part A did not assort independently, but instead were linked to one another on the same chromosome. Would you expect the phenotypic ratio in the offspring to change? If so, how?
All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes. Because all three genes are linked, it is more likely that the parental allele combinations would stay together rather than be recombined through a crossover event. That is why a greater proportion of the offspring would have parental phenotypes. Nevertheless, some crossing over would likely occur, which is why a small proportion of the offspring would have recombinant phenotypes.
The bonds or interactions that hold together adjacent nucleotides in the sugar-phosphate backbone of DNA are
Covalent
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.
During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'→5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand. For any given gene, what ultimately determines which DNA strand serves as the template strand?
D) the base sequence of the gene's promoter
Law that states that allele pairs segregate equally into gametes during meiosis. This means that a gamete will have only one allele of any given gene, and that the probability of a gamete having one allele or the other is equal (and therefore ½, or 50%, for either allele).
Law of Segregation
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 or segregation
For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Centromeres of sister chromatids disjoin and chromatids separate.
VII
The bonds or interactions between stacked nucleotide units that help hold the DNA molecule together are
Van der Waals interactions
During which phase of mitosis do the chromatids become chromosomes?
anaphase
A silent mutation
does not change the wild-type amino acid sequence.
The space-filling model shows
each atom making up the two strands, and reveals the helical shape and the double-stranded structure of the DNA molecule.
Asexual reproduction _____.
produces offspring genetically identical to the parent
At which phase of the cell cycle do centrioles begin to move apart in animal cells?
prophase
When chiasmata can first be seen in cells using a microscope, which of the following processes has most likely occurred?
prophase I
translation
rRNA tRNA
Which processes lead to most genetic variation in sexually reproducing organisms?
independent assortment of chromosomes in meiosis crossing over random fertilization
Besides the ability of some cancer cells to over proliferate, which of the following situations might logically result in a tumor?
lack of appropriate cell death
transcription/RNA processing
mRNA pre-mRNA snRNA
The leading strand is
made continuously from a single RNA primer located at the origin of replication. DNA pol III adds nucleotides to the 3' end of the leading strand so that it elongates toward the replication fork.
The lagging strand is
made in segments, each with its own RNA primer. DNA pol III adds nucleotides to the 3' end of the lagging strand so that it elongates away from the replication fork.
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?
meiosis I, anaphase Alleles separate from one another during anaphase of meiosis I, when the homologous pairs of chromosomes separate.
DNA nucleotides are composed of deoxyribose sugars, whereas RNA nucleotides are composed of
ribose sugars
Pyrimidines are
single-ring structures
You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.
sugar with two, and not three, oxygen atoms
In order for DNA polymerase to synthesize a complete new strand of DNA, it requires a
template to determine the order of bases on the new strand, a 3'-OH end to add more nucleotides onto, and the full set of four kinds of nucleotides (A,C,T,G) if they are needed to complement the template strand.
What materials does DNA polymerase require in order to synthesize a complete strand of DNA?
-All four deoxyribonucleotides triphosphates (containing A, C, T, or G) -Single-stranded DNA template -3'-OH end of the new DNA strand
Suppose that a portion of double-stranded DNA in the middle of a large gene is being transcribed by an RNA polymerase. As the polymerase moves through the sequence of six bases shown in the diagram below, what is the corresponding sequence of bases in the RNA that is produced? Diagram of DNA showing a coding strand and a template strand. Coding strand from 3' to 5' reads C C G A G T. Template strand from 5' to 3' reads G G C T C A. Enter the sequence of bases as capital letters with no spaces and no punctuation. Begin with the first base added to the growing RNA strand, and end with the last base added.
-UGAGCC There are three principles to keep in mind when predicting the sequence of the mRNA produced by transcription of a particular DNA sequence. The RNA polymerase reads the sequence of DNA bases from only one of the two strands of DNA: the template strand. The RNA polymerase reads the code from the template strand in the 3' to 5' direction and thus produces the mRNA strand in the 5' to 3' direction. In RNA, the base uracil (U) replaces the DNA base thymine (T). Thus the base-pairing rules in transcription are A→U, T→A, C→G, and G→C, where the first base is the coding base in the template strand of the DNA and the second base is the base that is added to the growing mRNA strand.
Helicase
-binds at the replication fork -breaks H-bonds between bases
topoisomerase
-breaks covalent bonds in DNA backbone -binds ahead of the replication fork
Mechanisms that contribute to genetic variation include
-errors (mutations) that occur during DNA replication -the production of recombinant chromosomes due to crossing over -the independent assortment of homologous chromosomes in meiosis I -the separation of sister chromatids (which are no longer identical due to crossing over) in meiosis II -the random fusion of male and female gametes during fertilization
In pea plants, the tall phenotype is dominant to the dwarf phenotype. If a heterozygous pea plant is crossed with a homozygous tall pea plant, what is the probability that the offspring will be dwarf in size?
0
The following question refers to the pedigree chart in the figure for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. Pedigree chart, row I: Male 1 ww (white square) mates with Female Ww (black circle.) Row II: their offspring: 2, black square; 3black circle, 4, black square, 6, 7, and 8, all white squares. Row III: 1, black square, offspring of Row II, number 2 and white circle. Row IV: offspring of row II, number 4 with white circle: 1, white circle; 2, white square; 3, black square, mates with 4, white circle. What is the probability that individual III-1 is Ww?
1
In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.
1' ... 5'
Place the events in the transcription of a gene in their proper order from left (first event) to right (last event). Rank from first event to last event.
1) RNA polymerase binds promoter 2) RNA polymerase transcribes gene 3) RNA polymerase reaches terminator 4) RNA polymerase exit gene. RNA is released
An individual with the genotype AaBbEeHH is crossed with an individual who is aaBbEehh. What is the likelihood of having offspring with the genotype AabbEEHh?
1/32 ( ½ x ¼ x ¼ x 1)
If a cell at metaphase of mitosis contains 20 sister chromatids, how many chromosomes will be present in a G1 cell?
10
Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?
A Cdk is an enzyme that attaches phosphate groups to other proteins.
Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?
A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.
After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes. Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
A) A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA. C) Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. E) A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
A nonsense mutation
causes an early Stop codon to occur.
Imagine a genetic counselor working with a couple who have just had a child who is suffering from Tay-Sachs disease. Neither parent has Tay-Sachs, nor does anyone in their families. Which of the following statements should this counselor make to this couple?
Because you have had one child with Tay-Sachs, you must each carry the allele. Any child you have has a 25% chance of having the disease
The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid. Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?
DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.
Which of these is a difference between a DNA and an RNA molecule?
DNA is usually double-stranded, whereas RNA is usually single-stranded.
What is the role of DNA polymerase during DNA synthesis?
DNA polymerase is the enzyme that catalyzes the addition of a nucleotide onto the 3' end of a growing DNA strand. DNA polymerase is the enzyme complex responsible for synthesizing a new strand of DNA, using an existing strand as a template.
The diagram below shows an mRNA molecule that encodes a protein with 202 amino acids. The start and stop codons are highlighted, and a portion of the nucleotide sequence in the early part of the molecule is shown in detail. At position 35, a single base-pair substitution in the DNA has changed that would have been a uracil (U) in the mRNA to an adenine (A). Based on the genetic code chart below, which of the following would be the result of this single base-pair substitution?
E. a nonsense mutation resulting in early termination of translation
Which of the following statements is true of a species that has a chromosome number of 2n = 16?
Each diploid cell has eight homologous pairs of chromosomes.
If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents?
It has half the amount of DNA as the cell that began meiosis.
True or False The -OH group on the 3' carbon of the sugar unit is the attachment site for the nitrogenous base
False
True or False The antiparallel arrangement of double-stranded DNA is due to the phosphate group being bonded to the 3' carbon on one strand and the 5' carbon on the complementary strand.
False
Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes eye problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?
It is pleiotropic.
Which of the following statements is correct regarding the human X chromosomes?
It is present in every somatic cell of males and females.
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?
G2
How are sister chromatids and homologous chromosomes different from each other?
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.
They carry information for the same traits
Homologous chromosomes of a pair are separated from each other.
Bonds that connect complementary bases from opposite strands of the DNA molecule and are relatively weak, low-energy interactions that allow complementary DNA strands to "unzip" during S phase replication.
Hydrogen bonds
The bonds or interactions that hold together complementary bases from opposite strands of DNA are
Hydrogen bonds
Use the figure to answer the question below. A diagram shows the amount of DNA in the nucleus increasing from bottom to top. From left to right, the diagram is divided into first cycle and second cycle. Each cycle is divided into three approximately equal columns and one much narrower section. A graph line runs across the sections, starting halfway up the column. It runs horizontally across the first column and is labeled I. It then rises to the top of the column; that line segment is labeled II. In the third column, labeled III, the line runs horizontally at the top of the column. In the narrow column, labeled IV, the line drops sharply back to its initial level. The line then runs horizontally through the first section of the second cycle, labeled V. The cycle continues to repeat itself. In the figure, G1 is represented by which numbered part(s) of the cycle?
I and V
Eukaryotic sexual life cycles show tremendous variation. Which of the following characteristics do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores
II, III, and IV Alternation of generations (not in animals) Spores ( only in plants)
Which of the following results from Griffith's experiment is an example of transformation?
In blood samples from the mouse in "d", living S cells were found.
Which of the following scenarios describes an example of epistasis?
In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.
Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation. Imagine that a prokaryote-like organism has been discovered in the polar ice on Mars. Interestingly, these Martian organisms use the same DNA → RNA → protein system as life on Earth, except that there are only 2 bases (A and T) in the Martian DNA, and there are only 17 amino acids found in Martian proteins
In the most general case of x bases and y bases per codon, the total number of possible codons is equal to xy . In the case of the hypothetical Martian life-forms, is the minimum codon length needed to specify 17 amino acids is 5 (25 = 32), with some redundancy (meaning that more than one codon could code for the same amino acid). For life on Earth, x = 4 and y = 3; thus the number of codons is 43, or 64. Because there are only 20 amino acids, there is a lot of redundancy in the code (there are several codons for each amino acid).
Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?
It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one.
During translation, nucleotide base triplets (codons) in mRNA are read in sequence in the 5' → 3' direction along the mRNA. Amino acids are specified by the string of codons. What amino acid sequence does the following mRNA nucleotide sequence specify? 5′−AUGGCAAGAAAA−3′ Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-Thr-Lys-Gly).
Met-Ala-Arg-Lys An amino acid sequence is determined by strings of three-letter codons on the mRNA, each of which codes for a specific amino acid or a stop signal. The mRNA is translated in a 5' → 3' direction.
What amino acid sequence does the following DNA nucleotide sequence specify? 3′−TACAGAACGGTA−5′ Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-His-Lys-Gly).
Met-Ser-Cys-His Before mRNA can be translated into an amino acid sequence, the mRNA must first be synthesized from DNA through transcription. Base pairing in mRNA synthesis follows slightly different rules than in DNA synthesis: uracil (U) replaces thymine (T) in pairing with adenine (A). The codons specified by the mRNA are then translated into a string of amino acids.
One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. Which of the following is the best explanation for why a young, affected child is the first in her family to be diagnosed?
One of the parents has a mild expression of the gene.
Which of the following statements is falsewhen comparing prokaryotes with eukaryotes?
Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do
Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant trait. If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F1 will be expected to exhibit which of the following phenotypes?
Purple and long
not used in protein synthesis
RNA primers
Addition of a nucleotide onto a DNA strand is an endergonic reaction. What provides the energy to drive the reaction?
Release of pyrophosphate from the incoming nucleotide, and then hydrolysis of the pyrophosphate to inorganic phosphate
How does natural selection apply to sexual reproduction as opposed to asexual reproduction?
Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction
DNA is transcribed to messenger RNA (mRNA), and the mRNA is translated to proteins on the ribosomes. A sequence of three nucleotides on an mRNA molecule is called a codon. As you can see in the table, most codons specify a particular amino acid to be added to the growing protein chain. In addition, one codon (shown in blue) codes for the amino acid methionine and functions as a "start" signal. Three codons (shown in red) do not code for amino acids, but instead function as "stop" signals. Sort the following ten codons into one of the three bins, according to whether they code for a start codon, an in-sequence amino acid, or a stop codon AUG, UAG, UAA, UGA, AAA, UGC, AUC, CAC, GCA, ACU
Start/Methionine AUG Stop codon UAG, UAA, UGA Amino acid AAA, UGC, AUC, CAC, GCA, ACU
Synthesis of the lagging strand is accomplished through the repetition of the following steps
Step 1: A new fragment begins with DNA polymerase III binding to the 3' end of the most recently produced RNA primer, primer B in this case, which is closest to the replication fork. DNA pol III then adds DNA nucleotides in the 5' to 3' direction until it encounters the previous RNA primer, primer A. Step 2: DNA pol III falls off and is replaced by DNA pol I. Starting at the 5' end of primer A, DNA pol I removes each RNA nucleotide and replaces it with the corresponding DNA nucleotide. (DNA pol I adds the nucleotides to the 3' end of fragment B.) When it encounters the 5' end of fragment A, DNA pol I falls off, leaving a gap in the sugar-phosphate backbone between fragments A and B. Step 3: DNA ligase closes the gap between fragments A and B.
Which diagram shows the details of the bonds between nitrogenous bases of complementary nucleotide pairs?
Structural Diagram only the structural diagram shows the molecular details--the specific number and location of hydrogen bonds that form between complementary base pairs.
Certain cell types normally have several nuclei per cell. How could such multinucleated cells be explained?
The cell underwent repeated mitosis, but cytokinesis did not occur.
Once a cell enters mitosis, the molecules that activate division must be turned off. What happens to MPF during mitosis?
The cyclin component of MPF is degraded.
Which of these gametes contains one or more recombinant chromosomes?
The gametes composed of material derived from both parents.
Which of the following statements about independent assortment or segregation is correct?
The law of independent assortment describes the behavior of two or more genes relative to one another
Suppose that the triplet of nucleotides indicated in bold (AGC) spans two codons, that is, CTA and GCC. If the triplet AGC were deleted from this DNA coding sequence, what effect would it have on the resulting protein? 5'-ATGCTAGCCTATCGTAAC-3'
The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift.
Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis. If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.
There would be less genetic variation among gametes.
Which of the following characteristics do homologous chromosomes exhibit?
They carry information for the same traits
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
Traits are inherited in discrete units and are not the result of "blending."
True or False Complementary base pairing relies on the number of hydrogen bonds that each base can make.
True
True or False In a single nucleotide, the phosphate group is attached to the 5' carbon of the sugar unit
True
True or False The phosphate attached to the 5' carbon of a given nucleotide links to the 3' -OH of the adjacent nucleotide
True
Nucleotides are composed of
a pentose sugar, a nitrogenous base, and a phosphate group.
A hydroxyl is present at the 3' end of the growing DNA strand. What is at the 5' end?
a phosphate group
Mendel's law of independent assortment has its basis in which of the following events of meiosis I?
alignment of pairs of homologous chromosomes along the middle of the cell
In the cells of many eukaryotic species, the nuclear envelope has to disappear to permit which of the following events in the cell cycle?
attachment of microtubules to kinetochores
single-strand binding protein
binds after the replication fork -prevents H-bonds between bases
In order for an insertion or deletion to cause a frameshift mutation, it must
cause the reading frame of each triplet of bases after it to be shifted by one or two places.
A missense mutation
causes a wild-type amino acid to be replaced by a different amino acid
How are human mitochondria inherited?
from the mother only
Which of the following processes occurs in a plant's sexual life cycle?
gametophytes produce gametes by mitosis
Which of the following terms associated with transcription describe regions of nucleic acid?
gene, prometer, terminator
What can we observe in order to visualize Mendel's Law of Segregation?
homologous chromosomes separating during meiosis I
Which of the following statements defines a genome?
the complete set of an organism's genes and other DNA sequences
A deletion is
the loss of part of a chromosomal segment.
An inversion is
the removal of a segment followed by its reinsertion into the same chromosome in the reverse orientation.
A duplication is
the repetition of a segment. The repeated segment may be located next to the original or at a different location, and its orientation may be the same as the original or the reverse.
A translocation is
the transfer of a segment to a nonhomologous chromosome. Translocations may be reciprocal (two nonhomologous chromosomes exchange segments) or nonreciprocal (one chromosome transfers a segment without receiving one).
Which of these nitrogenous bases is found in DNA but not in RNA?
thymine
In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
thymine ... cytosine This is referred to as specific base pairing.
Proteins that will ultimately function in the cytoplasm (PFK, for example) are
translated on free cytoplasmic ribosomes and released directly into the cytoplasm.
Proteins that are destined for the membranes or compartments of the endomembrane system, as well as proteins that will be secreted from the cell (insulin, for example), are
translated on ribosomes that are bound to the rough ER.
Each deoxyribonucleotide enters the reaction as a ___________, and hydrolysis of the phosphates releases the free energy needed for the nucleotide to bind to the growing strand
triphosphate
The DNA double helix is constructed from
two strands of DNA, each with a sugar-phosphate backbone and nitrogenous bases that form hydrogen bonds, holding the two strands together. Each DNA strand has two unique ends. The 3' end has a hydroxyl (-OH) group on the deoxyribose sugar, whereas the 5' end has a phosphate group. In the double helix, the two strands are antiparallel, that is, they run in opposite directions such that the 3' end of one strand is adjacent to the 5' end of the other strand.
Which of the following sequences shows a frameshift mutation compared to the wild-type mRNA sequence?
wild-type 5'-AUGCAUACAUUGGAGUGA-3' mutant 5'-AUGCAUACAUCUGGAGUGA-3'
Feather color in budgies is determined by two different genes, Y for pigment on the outside of the feather, and B for pigment on the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. Two blue budgies were crossed. Over the years, they produced 22 offspring, five of which were white. What are the most likely genotypes for the two blue budgies?
yyBb and yyBb
