遗传学题库---判断题

1、True-False Questions Answer each of the following questions either true (T or false (F.1. The phase of the cell cycle in which DNA replicates is designated S.2. A bivalent or a tetrad is a common feature of mitosis.3. The immediate product of the first meiotic division in animals is termed a spemnat

2、id.4. A diploid plant cell with the capacity to undergo meiosis is called a microspore.5. A micropyle is a small intracellular organelle.6. Double fertilization is a common attribute of angiospemris.7. Synapsis is a regular occurrence in meiosis.8. Barring mutation, the genetic tor tent of daughter

3、cells produced by mitosis should be identical.9. Sister chromatids separate from each other during first meiotic anaphase.10. None of the products of a meiotic event are expected to be genetically identical.True-Fake Questions Answer each of the following questions either true (T or false (F.1. A ph

4、enotype is either the product of gene or of environmental influences.2. Burring mutation, a pure line is expected to breed true to type.3. An individual with a hybrid genotype or in a carrier state must also be heterozygous.4. The simplest multiple allelic system consists of 3 alleles.5. A backcross

5、 is equivalent to a testcross.6. In pedigrees, circles represent males and squares represent females.7. The probabilities of independent events are added to rind the probability of their joint occurrence.8. Codominant alleles cannot express lethality when homozygous.9. Dominant trails are expected t

6、o be the most frequent phenotypes in a population.10. The F; generation is conventionally produced by random union of the F, gametes.True-Fake Questions Answer each of the following questions either true (T or false (F.1. A phenotype is either the product of gene or of environmental influences.2. Bu

7、rring mutation, a pure line is expected to breed true to type.3. An individual with a hybrid genotype or in a carrier state must also be heterozygous.4. The simplest multiple allelic system consists of 3 alleles.5. A backcross is equivalent to a testcross.6. In pedigrees, circles represent males and

8、 squares represent females.7. The probabilities of independent events arc added to rind the probability of their joint occurrence.8. Codominant alleles cannot express lethality when homozygous.9. Dominant trails are expected to be the most frequent phenotypes in a population.10. The F; generation is

9、 conventionally produced by random union of the F, gametes.True-False Questions Answer each of the following questions either true (T or false (F.1. Evidence that genes are linked is most effectively derived from intercrossing dihybrids.2. Each chiasma is equivalent to 1% crossing over.3. In a dihyb

10、rid testcross, progeny produced by 2-strand double crossovers will be indistinguishable from noncrossovers.4. The limit of recombination is 50%.5. If gene loci A and B are 15 map units apart (x physical units and if B and C loci are also 15 map units apart,then B and C must also be x physical units

11、apart.6. The larger the coincidence, the smaller the interference.7. Linkage distance estimates derived from F2 data depend entirely on the percentage of one phenotypic class in the progeny.8. In DrosophHa, crossing over occurs only in females.9. In lines of human-rodent somatic cell hybrids, rodent

12、 chromosomes are usually lost faster than humanchromosomes.10. Conidia arc the sexual spores of an ascomyecte.True-False Questions Answer each of the following questions either true (T or false (F. 1. The discipline of biology that attempts to correlate cellular events with genetic phenomena is cryo

13、genetics.2. Triploids and autotetraploids are usually sterile.3. Interspecific dipJoid hybrids are usually fertile.4. The genomic formula for a trisomic is 3«.5. Balanced lethal systems require either a translocation or an inversion to maintain heterozygosity generationafter generation.6. Overl

14、apping inversions have been used to locate the physical positions of linked genes.7. Production of viable recombination progeny resulting from crossing over within an inversion structuralheterozygote is not possible.8. Normal human males are sex-chromatin negative.9. Normal human females heterozygou

15、s for a pair of sex-linked allelcs have only one such allele expressed ina given cell.10. The phenomenon called gigantism is associated with the large polyiene chromosomes in certain celts ofDrosophila larvae.True-False Questions Answer each of the following questions either true (T or false (F. 1.

16、Quantitative traits are commonly studied by making counts and ratios of progeny phenotypes from parents of contrasting phenotypes.2. A parameter is a measurement derived from a sample.3. Most metric traits of economic importance have high heritabilities (ft1 greater than 0.5.4. Mass selection is the

17、 best method for improving metric trails with low heritabilities (h2 less than 0.2.5. Family selection is based upon the merits of ancestors.6. Matings between siblings are the most extreme form of inbreeding possible among sexually reproducing species.CHAP. 9 QUANTITATIVE GENETICS AND BREEDING PRIN

18、CIPLES 2457. Linebreeding is a special form of inbreeding used to maintain a high genetic relationship to a desired ancestor.8. Both inbreeding and positive assonative mating tend to reduce genetic heterozygosity, but the theoretical endresults are quite different.9. Loss of vigor (vegetative and/or

19、 reproductive commonly accompanies an increase in polygenic homozygosity.10. Most of our food is produced by mating methods that are essentially panmictic.True-False Questions Answer each of the following questions either true (T or false (F.1. If a genetic locus in a population is not in Hardy-Wein

20、berg equilibrium, it may be concluded that selectionfavors at least one of the genotypes.2. Two populations with identical allelic frequencies need not have identical genotype frequencies.3. Equilibrium at an autosomal locus can become fully established in a nonequilibrium population after onegenera

21、tion of random mating.4. Evolutionary processes are at work whenever deviations from equilibrium exist.5. The incidence of a dominant trait in a population is always greater than that of a recessive trait.6. The frequencies of recessive autosomal alleles cannot be obtained easily unless the populati

22、on is in geneticequilibrium.7. When autosomal allelic frequencies are dissimilar in the sexes, the genotypic frequencies become equilibratedin one generation of random mating.266 POPULATION GENETICS ICHAP. 108. The frequency of a sex-linked gene in XY males is equivalent to the frequency of that gen

23、e in the females(XX of the previous generation.9. The frequency of a sex-linked gene in females (XX is equal to the average of gene frequencies in males andfemales of the previous generation.10. The frequencies of linked genes approach equilibrium more rapidly if they are far apart than if they are lightlylinked.True-False Questions Answer each of the following statements either true (T or false (F.1. A single lambda phage particle cannot be cyclically permuted.2. Phage M13 infects E. coli but neither kills nor lyses its host cel