genetics quiz 2 – Flashcards

A mutation in a gene often results in a reduction of the product of that gene. The term for this type of mutation is: A. codominance B. incomplete dominance C. gain of function D. multiple allelism E. loss of function or null (in the case of complete loss)

Which of the following statements describe ways in which the environment can affect a genetic trait? A. genetically identical individuals are equally adapted to survive in different environments B.the environment can change both the genotype and phenotype of an organism C. the environment can limit the available resources required by an organism for normal development D. decreased exposure to certain environmental factors can decrease the risk of developing a specific disease

With incomplete dominance, a likely ratio resulting from a monohyrbrid cross would be: A) 3:3 B) 1:2:2:4 C) 1:2:1 D) 9:3:3:1 E) 3:1

A situation in which there are more than two alternative forms of a given gene would be called: A) multiple alleles B) alternation of generations C) codominance D) incomplete dominance E) hemizygosity

What would be a typical genotypic monohybrid ratio in which a lethal allele is involved? A) 2:1 B) 9:3:3:1 C) 6:2:3:1 D) 13:5 E) 3:1

A condition in which one gene pair masks the expression of a non allelic gene pair is called ____ A) codominance B) epitasis C) dominance D) recessiveness E) additive alleles

Select two examples that represent a phenocopy: A) the are three RAS genes, but mutation in any RAS gene are linked to cancer susceptibility B) individuals with mutations in the hemoglobin gene exhibit anemia and other symptoms C) the risk of acquiring type 2 diabetes is increased among individuals with high sugar intake D) in hot climates, himalyan rabbits develop a coat color that resemble that of albino rabbits E) Cataracts result from a viral infection during fetal development or from genetic mutations

Suppose baldness is controlled by a single gene with the following genotypes and phenotypes: Male (BB or Bb = bald, bb = non bald) Female (BB = bald, Bb or bb = non bald) A) sex-linked B) sex-influenced C) sex-limited D) sex-lethal

Which of these choices describe Y-linked traits? A) the trait is passed down to a son by his father B) a carrier female has a 25% chance of having a carrier daughter C) Females have a greater probability of being a carrier of that trait D) a male with the trait will pass the trait to 1005 of his female offspring

What term is applied when two genes fall to assort independently, that is, they tend to segregate together during gamete formation? A) discontinuous inheritance B) Mendelian inheritance C) linkage D) tetrad analysis E) dominance / recessive

Assume that a cross is made between AaBb and aabb plants and that all the offspring are either AaBb or aabb. These results are consistent with the following circumstance: A) complete linkage B) alternation of generation C) codominance D) incomplete dominance E) hemizygosity

In genetics, what is interference? A) it is the phenomenon in which a crossover even inhibits other crossover events from occurring nearby in the same region of a chromosome B) it is the situation in which alleles of different genes are associated with each other more frequently that chance C) It is the phenomenon in which genes are so physically close together on a chromosome that stye no longer assort independently D) it is the probability that a crossover occurs between two loci on a chromosome

Which statement is the definition of a map unit (centimorgan)? A) it is the percent chance of a recombination between two locations on a chromosome B) it is the distances equal to 100 base pairs of DNA C) It is the distance equal to 11/100 of the length of the chromosome D) it is the physical distance between neighboring genes on a chromosome

Which statement explains why the recombination frequency between two genes is always less than 50%? A) recombination cannot be more than 50% because chromosome are only 50 map units in length B) F1gametes always have 50% of their alleles from each parental gamete C) The genotype of the F1 gametes will always be 50% parental games and 50% recombinant gametes D) genes with a recombination frequency near 50% are unlinked and have an equal likelihood of being inherited together or separately

What relatively recent scientific advancement has made mapping by linkage or classical genetic mapping approaches virtually obsolete? A) the genome sequence of a species B) the inclusion of the X and Y chromosome in SNP experiments C) the use of syteny

Name the general category into which double-stranded circular extrachromosomal DNA elements such as F factors, ColE1, and R would fall. A) capsid B) t-determinant C) plaque D) partial diploid E) plasmid

how is circular DNA compacted within the nucleoid of a cell? A) supercoiling B) methylation C) histone coiling D) heterchromatin

Most bacteria and bacteriophages have circular chromosomes. Select the advantage of having circular chromosomes compared to linear chromosomes A) easier to segregate during cell division B) more open reading frames C) no interlinking during replication

Which of the following definitions describe conjugation in bacteria: A) the movement of genes into a bacterial recipient cell via a phage vector B) free DNA in the extracellular environment is taken up by bacterial cells C) DNA is transferred from a donor to a recipient cell via a direct connection D) spores fuse to create a zygote

Bacteriophages engage in two interactive cycles with bacteria. What are these cycles? A) lytic and lysogenic B) auxotrophic and prototrophic C) insertion and replication D) heteroduplex and homoduplex E) negative and positive

name two forms of recombination in bacteria A) a portion of the Y chromosome B) one X chromosome C) high levels of estrogen D) multiple alleles scattered throughout the autosomes

earthworms contain ovaries in one segment and testes in another segment of their body. which term describes the sex system of the organism? A) ZW sex determination B) XO sex determination C) XY sex determination D) dioecious E) monoecious

Select the scenario that demonstrate environmental sex determination: A) a greater proportion of offspring of a species of fish in Cali develop into female when their larvae are exposed to a longer day photoperiod that expected B) an XY individual has a deletion of the SRY gene from the Y chromosomes. The individual develops a female characteristics despite the presence of a Y chromosome. species of marine worm releases larvae into the ocean. larvae that land on the ocean develop into females and have a long proboscis and uterus C) eggs from red eared slider turtle are exposed to unusually cold temperatures in the late stages of the development resulting in offspring in the brood are male D) the offspring of a mating between a male and female grasshopper is a male with XO sex chromosome E) during early human development, nondisjunction of sex chromosomes occur during cell division

A recessive gene for red-green color blindness is located on the X chromosome of humans. Assume that woman with normal vision (her father is color blind) married a color-blind male. What is the likelihood that this couple's first son will be color blind? A) 0% B) 25% C) 50% D) 75% E) 100%

the sex of birds, some insects, and other organisms is determined by a ZW chromosomal arrangement in which the males have the sex chromosomes (ZZ) and females are (ZW). Assume that a recessive lethal allele on the chromosome causes death of an embyro in birds. What sex ratio would result in the offspring if a cross were made between a male heterozygous for the lethal allele and a normal female? A) 4:1 male to female B) 2:! male to female C) 3:1 male to female D) 1:2 male to female E) 1:1 male to female

in Drosophilia melanogaster, the level of expression of genes on the X chromosome in males is doubled. What phenomenon is this an example of? A) dosage compensation B) extranuclear inheritance C) genomic imprinting D) paternal mitochondrial leakage

A black female cat is mater with an orange male cat. They produce two tortoiseshell females, two black males, one orange female, and one tortoiseshell male, for a total of six kittens. Orange and black fur color are encoded by different alleles of the same X linked fur color genes. Based on the phenotypes of the parents, what sex chromosomes do the orange female and the tortoise male offspring have? A) the orange female is XX, and the tortoiseshell male is missing a Y chromosome B) the orange female is XX< and the tortoiseshell male is XXY C) the orange female is XO, and the tortoiseshell male has one Y chromosome and more than one X chromosome D) the orange female is XO, and the tortoiseshell male is XY

certain behavioral traits in humans are believed to be encoded in the x chromosome. examples of such traits include verbal ability and seeking social interactions. for these traits, research has shown that there is less variability and seeking social interactions. for these traits, research has shown that there is less variability between identical male twins than between identical female twins. which phenomenon best explains these results? A) male twins both get the same mitochondria from their mother B) males have a Y chromosome, which is much smaller than the X C) only one X chromosome is active in females D) females have double the amount of X expression so there's more room for error

select the true statements regarding the roles of sex chromosomes in human development: A) XO females are viable whereas YO males are inviable B) a female with a translocated SRY region on an autosome will develop testes C) male cells typically contain two X chromosomes, one of which is turned off D) XXY males are often sterile E) the X chromosome does not contain functional genes

in humans, the genetic basis for determining the sex "male" is accomplished by the presence of ___ A) a portion of the Y chromosome B) one X chromosome C) high levels of estrogen D) multiple alleles scattered throughout the autosomes

How many different alleles can a gene have?

Under what circumstance might 2 loci be on the same chromosome but behave as if independently assort in in crosses?

Assume that a cross is made between two organisms that are both heterozygous for a gene that shows incomplete dominance. What phenotypic and genotypic ratios are expected in the offspring?

In the mouse, gene A allows pigmentation to be deposited in the individual coat hairs; its allele a prevents such deposition of pigment, resulting in albino. Gene B gives agouti (wild-type fur); its allele b gives black fur. A) diagram the cross between a double heterozygous agouti mouse mated with a double homozygous recessive white mouse B) what would be the expected phenotypic ratio in the progeny?

Assume that a dihybrid F2 ratio, resulting from epistasis, was 9:3:4. if a double heterozygote was crossed with the fully recessive type, what phenotypic ratio is expected among the offspring?

Dosage compensation in mammals typically involves the random inactivation of one of the two x chromosomes relatively early in development. such x chromosome inactivation often leads to phenotypic mosaicism. assume that black fur in cats is due to the x-linked recessive gene b, whereas its dominant allele B produces yellow fur. A Bb heterozygote is a mosaic called "tortoise shell" or "calico". Using appropriate gene symbols, diagram a mating between a black male and a calico female. give the phenotypes and genotypes of all of the offspring.

Assume that the genes for tan body and bare wings are 15 map units apart on chromosome II in Drosophilia. Assume also that a tan-bodied, bare winged female was mated to a wilds-type male and that the exulting F1 phenotypically wild-type females were mated to tan bodied, bare-winged males. Of 1000 offspring, what would be the expected phenotypes, and in what numbers would they be expected?

Assume that investigators crossed a strain of flies carrying the dominant eye mutation Lobe on the second chromosome with a strain of homozygous for the second chromosome recessive mutations smooth abdomen and straw body. The F1 lobe females were then backcrossed with homozygous smooth abdomen, straw body males, and the following phenotypes were observed: Smooth abdomen, straw body 820 lobe 780 smooth abdomen, lobe 42 straw body 58 smooth abdomen 148 lobe, straw body 152 Give the gene order and map units between these three loci.