AGB Quiz 35 Quiz InstructionsThis quiz consists of 20 multiple-choice questions.You will be awarded 5 marks for each correct answer. Question 1: In a breeding program, how is the realized heritability (h2) of a quantitative trait estimated over several generations?Regression of response on cumulative selection differentialCorrelation between phenotype and breeding valueRatio of phenotypic variance to genetic varianceRatio of environmental variance to selection differential Question 2: In the equation representing the change of mean phenotypic value resulting from inbreeding (-2Fpqd), under what condition will a locus fail to contribute to the change of mean?When the gene frequencies of the alleles are at intermediate values of 0.5When the degree of dominance (d) is equal to zeroWhen the inbreeding coefficient (F) reaches its maximum value of 1.0When the alleles are at unequal frequencies in the population Question 3: Which of the following quantitative characters in livestock is highly sensitive to inbreeding depression?Butter fat percentage in dairy cattleGrowth rateBack fat thickness in pigsEgg size in poultry Question 4: What is the direct biochemical failure that leads to the hereditary condition known as Phenylketonuria (PKU) in humans?Failure to convert tyrosine into dihydroxy phenylalanineInability to synthesize thyroxine and triiodothyronineFailure to convert phenylalanine to tyrosineAccumulation of homogentisic acid in the cartilages Question 5: At what life stage does excess phenylalanine primarily interfere with brain development in individuals affected by Phenylketonuria (PKU)?First 5 years of lifePrenatal stage onlyFrom age 5 to 10 yearsThroughout the entire lifetime Question 6: Alkaptonuria is a metabolic disorder resulting from a genetic block in the breakdown of homogentisic acid. Which clinical condition are alkaptonuric patients prone to developing later in life?AlbinismGoitrous cretinismDegenerative arthritisSevere mental retardation Question 7: Which bacterial genetic recombination mechanism involves the transfer of genetic material mediated by a bacteriophage?TransformationConjugationTransductionSexduction Question 8: What is the genetic basis of a phenogroup as observed in cattle blood group typing?Multiple independent alleles at widely separated chromosomesA group of factors almost always transmitted as a unit, produced by closely linked genesAntigens produced by the interaction of light and heavy immunoglobulin chainsSoluble macromolecules that change continuously throughout the animal's life Question 9: Neonatal isoerythrolysis, a hemolytic anemia of newborns caused by colostral antibody absorption, occurs primarily in which species?Cattle and sheepSwine and poultryHorses and dogsMice and rabbits Question 10: What is the term used to describe the developmental shaping of an embryo as it increases in size by growth?EpigenesisMorphogenesisPhenogenesisSenescence Question 11: Match the researchers in Column I with their respective discoveries or theories in Column II:Column I:1. Beadle and Tatum2. Garrod3. Landsteiner4. H.G. KhoranaColumn II:P. Inborn errors of metabolismQ. One gene one enzyme theoryR. Artificial synthesis of tRNA geneS. ABO blood groups1-Q, 2-P, 3-S, 4-R1-P, 2-Q, 3-R, 4-S1-Q, 2-R, 3-P, 4-S1-S, 2-P, 3-Q, 4-R Question 12: Match the genetic metabolic disorders listed in Column I with their primary enzyme-mediated biochemical blocks listed in Column II:Column I:1. Albinism2. Genetic goitrous cretinism3. Phenylketonuria4. AlkaptonuriaColumn II:P. Failure to convert phenylalanine to tyrosineQ. Block in converting tyrosine to dihydroxy phenylalanineR. Failure to convert tyrosine to thyroid hormones (thyroxine)S. Defect in converting homogentisic acid to CO2 and water1-Q, 2-R, 3-P, 4-S1-P, 2-Q, 3-R, 4-S1-R, 2-Q, 3-S, 4-P1-Q, 2-P, 3-R, 4-S Question 13: Match the bacterial genetic recombination terms in Column I with their descriptions in Column II:Column I:1. Transformation2. Conjugation3. Transduction4. SexductionColumn II:P. One-way transfer of DNA through a cytoplasmic bridgeQ. Naked DNA absorption by a bacterial cellR. Bacterial gene transfer mediated by a virus (bacteriophage)S. Transmission of bacterial genes on an F plasmid molecule acting as a sex factor1-Q, 2-P, 3-R, 4-S1-P, 2-Q, 3-S, 4-R1-Q, 2-R, 3-P, 4-S1-R, 2-P, 3-Q, 4-S Question 14: Evaluate the correctness of the following statements regarding the genetic mechanisms of inbreeding and heterosis:I. Heterosis is completely absent when quantitative traits are influenced only by additive gene effects.II. Crosses made at random between inbred lines without selection are expected to have a mean value equal to that of the base population.III. The amount of heterosis expected in crossing is represented by the formula dy2, where d is dominance and y is the difference in gene frequency.IV. Continuous inbreeding increases the genetic variance within lines while reducing the genetic differences between lines.I, II, and III are correct; IV is incorrectI and III are correct; II and IV are incorrectII and IV are correct; I and III are incorrectAll statements (I, II, III, and IV) are correct Question 15: Evaluate the following statements regarding the genetic control and structure of immunoglobulins (antibodies):I. Light (L) and heavy (H) chains of antibodies are synthesized from genes located on the same chromosome to ensure synchronous assembly.II. The light chain gene cluster comprises several hundred variable (V) genes, four joining (J) genes, and one constant (C) gene.III. The heavy chain gene cluster consists of approximately eight V and J genes, and eight diversity (D) genes.IV. The extent of antibody production in the body is regulated by genes other than those encoding the antibody chains.I and II are correct; III and IV are incorrectII, III, and IV are correct; I is incorrectI, III, and IV are correct; II is incorrectAll statements are correct Question 16: Evaluate the following statements regarding the biochemical synthesis of methionine in Neurospora crassa as studied by Fisher (1957):I. Methionine is synthesized in a step-wise chain of chemical reactions: Cysteine -> Cystathionine -> Homocysteine -> Methionine.II. A mutant lacking the enzyme to convert cystathionine to homocysteine can grow if supplied with either homocysteine or methionine.III. A mutant lacking the enzyme to convert cysteine to cystathionine will grow normally if supplied with only cysteine.IV. Mutations at any one of the four loci in this pathway result in strains that are auxotrophic to methionine.I, II, and IV are correct; III is incorrectI and III are correct; II and IV are incorrectII and III are correct; I and IV are incorrectAll statements are correct Question 17: Assertion: A breeder has no direct control over the genetic variability (sigma_A) of a trait in a population.Reason: To improve selection response, the breeder must focus on improving the heritability (h2) by reducing environmental variation through management and rearing techniques.Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.Assertion is true, but Reason is false.Assertion is false, but Reason is true. Question 18: Assertion: Haploid microorganisms, such as bacteria and viruses, provide an excellent opportunity for studying gene structure and expression at the molecular level.Reason: Asexual reproduction in bacteria is carried out by amitosis, which is a direct nuclear division without the formation of condensed chromosomes or spindle fibers.Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.Assertion is true, but Reason is false.Assertion is false, but Reason is true. Question 19: The average egg production in a flock of White Leghorn chickens is 180 eggs per year. A breeder selects individuals from this flock, and the average performance of the selected group is 240 eggs per year. If the heritability of egg production is 0.3, what is the expected genetic progress in the next generation?18 eggs per year60 eggs per year12 eggs per year30 eggs per year Question 20: In a herd of cattle, the average one-year weight was 800 pounds. Selected breeding males and females averaged 1000 and 825 pounds, respectively. The average one-year weight of the progeny in the next generation was 845 pounds. Estimate the realized heritability (h2) of the trait.0.250.400.330.50
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