p.17
Chi-Squared Test in Genetics
What is the degree of freedom for this chi-squared test?
1 (number of phenotypes - 1).
p.11
Genetic Diagrams and Dihybrid Crosses
What is the phenotypic ratio for the cross PpQq x PpQq assuming inhibitor B is absent?
The phenotypic ratio is 9:3:3:1.
p.4
Genetic Diagrams and Dihybrid Crosses
What are the parental phenotypes in the genetic cross?
Red, tall and White, short.
p.2
Inheritance Mechanisms
What is the human genome composed of?
23 pairs of chromosomes: 1 pair of sex chromosomes (XX or XY) and 22 pairs of autosomal chromosomes.
p.8
Gene Interaction and Epistasis
What are the parental genotypes for the rose and pea comb chickens?
Rose comb: RRpp; Pea comb: rrPP.
p.9
Gene Interaction and Epistasis
What is epistasis?
A form of gene interaction where one gene masks or modifies the phenotypic expression of another gene.
p.17
Chi-Squared Test in Genetics
How many total plants were observed in the F2 generation?
80 plants (66 red + 14 white).
p.2
Linkage and Crossing-Over
When does crossing over occur?
During prophase I of meiosis.
p.4
Gene Interaction and Epistasis
What does it mean that linked genes do not assort independently?
It means they do not follow Mendel’s second law.
p.11
Gene Interaction and Epistasis
What is complementary gene action?
It is an epistatic interaction where both genes are required for the expression of a phenotype.
p.4
Linkage and Crossing-Over
Why can't the proportion of different gametes be predicted?
Because crossing over is random.
p.11
Gene Interaction and Epistasis
What is epistasis?
Epistasis is the interaction between genes where one gene's expression is affected by another gene, often observed in enzymatic pathways.
p.5
Genetic Diagrams and Dihybrid Crosses
What was the expected ratio of different types of offspring in the F2 generation?
The expected ratio was 3:1.
p.2
Linkage and Crossing-Over
What is genetic linkage?
Genetic linkage occurs when two separate genes are found on the same chromosome and are inherited together if there is no crossing over.
p.5
Genetic Diagrams and Dihybrid Crosses
What are the genotypes of the F1 generation in the tomato cross?
All F1 plants have the genotype for yellow flowers and red fruit.
p.5
Genetic Diagrams and Dihybrid Crosses
What phenotypes and their numbers were observed in the actual F2 generation?
Yellow flowers and red fruit: 68, Yellow flowers and yellow fruit: 7, White flowers and red fruit: 7, White flowers and yellow fruit: 18.
p.17
Chi-Squared Test in Genetics
What is the expected Mendelian ratio for a monohybrid cross?
3:1 ratio for dominant to recessive traits.
p.10
Gene Interaction and Epistasis
What is dominant epistasis?
The dominant genotype at one gene (A_) produces a certain phenotype regardless of the allelic condition of the other gene (B/b).
p.14
Genetic Diagrams and Dihybrid Crosses
What is the expected phenotypic ratio of the offspring from the test-cross of a homozygous unbanded pink-shelled snail with a homozygous banded yellow-shelled snail?
1 pink unbanded : 1 pink banded : 1 yellow unbanded : 1 yellow banded.
p.6
Linkage and Crossing-Over
How does the proximity of linked genes affect the probability of recombinants being formed?
The closer the genes are, the smaller the chance their alleles will be separated during crossing over.
p.19
Types of Genetic Variation
What is discontinuous variation?
Variation where individuals show clear-cut differences with no intermediates between them.
p.6
Mapping Genes and Genetic Distances
What does 1% crossover value (COV) correspond to in genetic mapping?
1% COV equals 1 map unit or 1 centimorgan (cM).
p.20
Genetic Diagrams and Dihybrid Crosses
What is the genetic composition of the F2 generation?
It consists of many different genotypes resulting from crossing F1 heterozygotes.
p.20
Gene Interaction and Epistasis
What indicates that cob length is genetically determined?
The additive effect of many genes contributing to cob length.
p.16
Chi-Squared Test in Genetics
What does it indicate if the calculated X² value is greater than the theoretical X² value?
Significant differences between the observed and expected data.
p.8
Gene Interaction and Epistasis
What is gene interaction?
The interaction between two or more genes that influences the outcome of a single trait.
p.3
Genetic Diagrams and Dihybrid Crosses
How are linked genes represented in a genetic diagram?
Alleles found on the same chromosome are represented together with a line representing the chromosome.
p.2
Linkage and Crossing-Over
What happens during crossing over?
It involves the exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis.
p.12
Gene Interaction and Epistasis
What is the result of having one active enzyme in the enzymatic pathway for yellow pigment synthesis?
The presence of any one active enzyme results in the production of yellow pigment.
p.15
Chi-Squared Test in Genetics
What is the null hypothesis in a Chi-Squared test?
It states that there are no significant differences between the observed and expected data, and any differences are due to chance.
p.13
Gene Interaction and Epistasis
How does the allele B affect the gene M/m?
The dominant allele B results in unbanded shells, masking the effect of the M/m alleles.
p.17
Chi-Squared Test in Genetics
What are the expected numbers of red and white flowers based on the Mendelian ratio?
Expected red flowers: 60; Expected white flowers: 20.
p.2
Linkage and Crossing-Over
Do alleles of linked genes assort independently?
No, they do not assort independently but are inherited together if there is no crossing over.
What is gene reshuffling?
The reshuffling of existing alleles during meiosis, resulting in new combinations of alleles.
p.6
Linkage and Crossing-Over
What is the purpose of calculating the crossover value (COV)?
To determine the distance between two linked genes based on the proportion of recombinants formed.
p.3
Genetic Diagrams and Dihybrid Crosses
What are the observed numbers of F2 plants?
86 tall red, 14 tall white, 11 short red, 89 short white.
p.10
Gene Interaction and Epistasis
What does allele G code for in squash fruit color?
Production of green pigments.
p.19
Types of Genetic Variation
What controls the characteristic in continuous variation?
The additive effect of many genes (polygenes).
p.4
Inheritance Mechanisms
What is the significance of meiosis in genetics?
Meiosis produces gametes for sexual reproduction.
p.11
Gene Interaction and Epistasis
How does the production of red pigment depend on yellow pigment?
The production of red pigment is dependent on the presence of yellow pigment; if inactive enzyme P or inhibitor B is present, only white pigment is produced.
p.12
Gene Interaction and Epistasis
What is epistasis in genetics?
A gene at one locus may produce the same phenotype as another gene at a second locus.
p.4
Genetic Diagrams and Dihybrid Crosses
What is the F1 generation's genotype and phenotype?
Genotype: Red, tall; Phenotype: Red, tall.
p.3
Genetic Diagrams and Dihybrid Crosses
What is a common mistake when drawing genetic diagrams for alleles?
Drawing both alleles of the same gene on the same line instead of on homologous chromosomes at the same gene locus.
p.12
Gene Interaction and Epistasis
What happens if both enzymes A and B are inactive?
There will only be white pigment.
p.15
Chi-Squared Test in Genetics
What does it mean if the null hypothesis is not rejected?
It indicates that there are no significant differences between the observed and expected data.
p.18
Environmental Effects on Phenotype
How does the environment contribute to variation?
Environmental factors may affect gene expression, leading to phenotypic variation.
p.20
Environmental Effects on Phenotype
What is the phenotypic variation in cob length attributed to in the parental varieties?
Effects of the environment.
p.10
Gene Interaction and Epistasis
What phenotype does allele D produce in squash fruit color?
It suppresses the expression of gene G/g, leading to white fruits.
p.17
Chi-Squared Test in Genetics
What should be done after calculating the X² value?
Compare it to the theoretical X² value to draw a conclusion.
p.20
Gene Interaction and Epistasis
What is the cob length in the F1 generation compared to the parental varieties?
It is intermediate between the two parental varieties.
p.10
Gene Interaction and Epistasis
What is the phenotype of the F1 generation when a white fruit plant is crossed with a yellow fruit plant?
All F1 generation produces white fruits.
p.9
Gene Interaction and Epistasis
What will be the F2 phenotypic ratio when crossing F1 black Labrador retrievers?
9 black : 3 brown : 4 golden.
p.19
Types of Genetic Variation
How many genes typically control a trait exhibiting discontinuous variation?
1 or 2 genes with 2 or more allelic forms.
p.19
Types of Genetic Variation
What is continuous variation?
Variation where individuals show a complete gradation from one extreme to another without a break.
What is the difference between dominant and recessive alleles?
Dominant alleles express their traits even in the presence of a recessive allele, while recessive alleles only express their traits when homozygous.
p.1
Environmental Effects on Phenotype
How can the environment affect phenotype?
Environmental factors, such as diet and temperature, can influence the expression of traits, as seen in honey bees and Himalayan rabbits.
p.17
Chi-Squared Test in Genetics
What is the null hypothesis in a chi-squared test for flower color inheritance?
The inheritance of flower color follows the expected Mendelian ratio.
p.9
Gene Interaction and Epistasis
How does epistasis affect the number of phenotypic classes in a dihybrid cross?
It decreases the number of phenotypic classes from four to three or even two.
p.20
Genetic Diagrams and Dihybrid Crosses
What two varieties of maize were crossed in the classic experiment by Ralph Emerson and Edward East?
Tom Thumb and Black Mexican Corn.
p.9
Gene Interaction and Epistasis
What is recessive epistasis?
A situation where the recessive genotype of one gene suppresses the expression of another gene.
p.2
Linkage and Crossing-Over
What are recombinant chromosomes?
Chromosomes that result from the exchange of genetic material during crossing over.
p.15
Chi-Squared Test in Genetics
What is the first step in carrying out a Chi-Squared test?
To obtain the calculated Chi-Squared value.
p.9
Gene Interaction and Epistasis
What determines the coat color of Labrador retrievers?
Two genes: B/b for pigment synthesis and E/e for pigment deposition.
p.20
Inheritance Mechanisms
How is the F1 generation different from the parental varieties?
The F1 generation is a hybrid and genetically different from either parent but identical to each other.
p.10
Gene Interaction and Epistasis
What are the genotypes of the parents in the squash fruit color example?
DDGG for the plant with white fruits and ddgg for the plant with yellow fruits.
p.18
Types of Genetic Variation
What is gene mutation?
Changes in the DNA sequence of a gene that result in new alleles coding for altered proteins.
p.14
Chi-Squared Test in Genetics
What is the purpose of conducting a chi-squared test in genetics?
To deduce the mode of inheritance of the genes by determining if observed data fits expected ratios.
p.15
Chi-Squared Test in Genetics
How is the degree of freedom calculated for a Chi-Squared test?
It is equal to the number of phenotypic classes minus 1.
p.19
Types of Genetic Variation
How is the frequency histogram of continuous variation characterized?
It shows a smooth curve, usually a bell-shaped normal distribution curve.
p.16
Chi-Squared Test in Genetics
What are the two ways to use the calculated X² value?
i. Comparing theoretical X² value with calculated X² value ii. Comparing the probability level.
What is codominance?
A genetic scenario where both alleles in a heterozygote are fully expressed, resulting in a phenotype that is neither dominant nor recessive.
p.1
Gene Interaction and Epistasis
How is genotype linked to phenotype?
Genotype refers to the genetic makeup of an organism, which determines its phenotype, or observable traits.
p.5
Genetic Diagrams and Dihybrid Crosses
What was the total number of plants with white flowers in the F2 generation?
25 plants (7 with red fruit and 18 with yellow fruit).
p.14
Inheritance Mechanisms
What is meant by the term linkage in genetics?
Linkage refers to the tendency of genes that are located close to each other on a chromosome to be inherited together during meiosis.
p.3
Genetic Diagrams and Dihybrid Crosses
What are the genotypes of the parental plants in the example provided?
Tall plant with red flowers (RRTT) crossed with short plant with white flowers (rrtt).
p.12
Gene Interaction and Epistasis
What is the phenotypic ratio for the cross AaBb x AaBb in the context of epistasis?
The phenotypic ratio is 9:3:4 for recessive epistasis.
p.6
Linkage and Crossing-Over
What are recombinants in genetics?
Recombinants are formed when crossing over occurs between linked genes.
p.11
Genetic Diagrams and Dihybrid Crosses
What is the phenotypic ratio for the cross RrGg x RrGg?
The phenotypic ratio is 9:7.
p.4
Gene Interaction and Epistasis
What is observed about the proportion of parental phenotypes?
There is a higher proportion of individuals showing parental phenotypes.
p.14
Types of Genetic Variation
Why might observed numbers differ from expected ratios in genetic crosses?
Differences may be due to chance or other factors, such as alleles not assorting independently.
p.10
Gene Interaction and Epistasis
What are the observed numbers of phenotypes in the F2 generation?
122 white fruits, 37 green fruits, and 11 yellow fruits.
p.16
Chi-Squared Test in Genetics
In the example provided, what was the calculated X² value and how does it compare to the theoretical X² value?
Calculated X² value is 0.79, which is smaller than the theoretical X² value of 7.82.
p.1
Linkage and Crossing-Over
What is linkage in genetics?
The tendency of genes located close together on a chromosome to be inherited together.
p.18
Types of Genetic Variation
What is variation in the context of organisms?
Differences in characteristics observed in organisms of the same natural population or species.
p.8
Gene Interaction and Epistasis
What phenotypes result from the F2 generation of the comb shape cross?
Walnut comb, Rose comb, Pea comb, Single comb.
p.18
Types of Genetic Variation
What causes phenotypic variation?
Variation in genotypes and interaction between genes and the environment.
What does it mean that both parental varieties were pure-bred?
Each variety is homozygous at the gene loci determining cob length, making individuals genetically identical.
p.3
Genetic Diagrams and Dihybrid Crosses
What is the genotype of the F1 plants?
All F1 plants are heterozygous (RrTt).
p.12
Gene Interaction and Epistasis
How does epistasis affect phenotypic variation?
Epistasis reduces the number of different phenotypes appearing in the progeny, thus reducing phenotypic variation.
p.14
Chi-Squared Test in Genetics
What does a chi-squared (X²) test compare in genetics?
It compares the differences between observed and expected data to determine if the observed data conforms to the expected data.
p.6
Linkage and Crossing-Over
What is the formula for calculating recombination frequency?
Recombination frequency = (Number of recombinants / Total number of offspring) x 100%.
p.18
Types of Genetic Variation
What are chromosomal aberrations?
Changes in the structure or number of chromosomes that lead to new combinations of alleles.
p.6
Linkage and Crossing-Over
What is a linkage group?
A linkage group consists of all the genes on a chromosome that are inherited together.
p.6
Mapping Genes and Genetic Distances
How can geneticists produce chromosome maps?
By calculating the COVs between all gene pairs on a chromosome to show the relative locations of genes.
p.19
Types of Genetic Variation
How does the environment affect continuous variation?
It is usually affected by the environment, but not necessarily.
What is incomplete dominance?
A genetic situation where the phenotype of a heterozygote is intermediate between the phenotypes of the two homozygotes.
p.11
Genetic Diagrams and Dihybrid Crosses
What is the phenotypic ratio for the cross BbQq x BbQq assuming enzyme P is active?
The phenotypic ratio is 9:3:3:1.
p.4
Genetic Diagrams and Dihybrid Crosses
What are the observed numbers of phenotypes in the F2 generation?
Red, tall: 86; White, short: 89; Red, short: 11; White, tall: 14.
p.11
Gene Interaction and Epistasis
What is required for the synthesis of purple pigment in the second enzymatic pathway?
Both active enzyme R and enzyme G must be present.
p.17
Chi-Squared Test in Genetics
What is the formula for calculating the chi-squared (X²) value?
X² = Σ((Observed - Expected)² / Expected).
p.13
Genetic Diagrams and Dihybrid Crosses
What is the phenotypic ratio of the F2 generation from the cross of BBMM and bbmm?
9 unbanded: 3 mid-banded: 4 five-banded.
p.15
Chi-Squared Test in Genetics
What type of data is required for a Chi-Squared test?
Discrete data, which means absolute numbers, not proportions or percentages.
p.2
Linkage and Crossing-Over
What is the effect of crossing over on gamete formation?
It increases genetic variation by producing recombinant gametes.
p.3
Genetic Diagrams and Dihybrid Crosses
Do the observed numbers of F2 plants follow the expected Mendelian ratio?
Yes, the observed numbers approximate the expected Mendelian ratio.
p.20
Types of Genetic Variation
Why does the F2 generation show a wider range of variation in cob length?
Due to both genetic variation and environmental effects.
p.10
Gene Interaction and Epistasis
What does allele g code for in squash fruit color?
Production of yellow pigments.
p.6
Linkage and Crossing-Over
What type of cross is used to determine the frequency of formation of recombinants?
A test cross is carried out on the F1 offspring that are double heterozygous.
What is the definition of 'locus' in genetics?
The specific location of a gene on a chromosome.
p.16
Chi-Squared Test in Genetics
What conclusion can be drawn if the observed data follows the expected Mendelian 9:3:3:1 distribution?
Do not reject the null hypothesis; any differences observed are due to chance.
p.1
Chi-Squared Test in Genetics
What is the chi-squared test used for in genetics?
To test the significance of differences between observed and expected results in genetic experiments.
What processes contribute to gene reshuffling?
Crossing-over, independent assortment, and random fertilization of gametes.
p.15
Chi-Squared Test in Genetics
What does the top row of the probability table represent?
It shows the probabilities that differences between observed and expected data are due to chance.
p.20
Environmental Effects on Phenotype
What contributes to the phenotypic variation in cob length in the F1 generation?
Effects of the environment.
p.19
Types of Genetic Variation
How is the frequency histogram of discontinuous variation characterized?
It has separate bars for each distinct class.
p.16
Chi-Squared Test in Genetics
What probability level indicates no significant differences between the observed and expected data?
If the probability is greater than 0.05.
p.1
Linkage and Crossing-Over
What is crossing-over?
The exchange of genetic material between homologous chromosomes during meiosis, which can affect phenotypic ratios.
p.16
Chi-Squared Test in Genetics
What does it indicate if the calculated X² value is smaller than the theoretical X² value?
No significant difference between the observed and expected data.
p.1
Genetic Diagrams and Dihybrid Crosses
What is the purpose of genetic diagrams in dihybrid crosses?
To solve problems involving inheritance patterns, including codominance, incomplete dominance, and epistasis.
p.1
Gene Interaction and Epistasis
What is epistasis?
The interaction between genes at different loci, where one gene can mask or modify the expression of another.
p.1
Types of Genetic Variation
What is the difference between continuous and discontinuous variation?
Continuous variation is controlled by many additive genes, while discontinuous variation is controlled by one or a few genes.
p.1
Inheritance Mechanisms
How are genes inherited from one generation to the next?
Genes are inherited via germ cells or gametes during reproduction.
