Genetics Exam test questions and
answers graded A+
Describe Mendelian genetics - ANS✅✅-true breeding
-self-fertilization
-highly homozygous
-peas
-Mendel picked discrete traits (binary phenotype)
what is a gene - ANS✅✅an inherited factor (encoded in the DNA) that helps determine a
characteristic
what is an allele - ANS✅✅one of two or more alternative forms of a gene
what is a locus - ANS✅✅a specific place on a chromosome occupied by an allele
what is a genotype - ANS✅✅set of alleles possessed by an individual organism
what is a heterozygote - ANS✅✅an individual organism possessing two different alleles at a locus
what is a homozygote - ANS✅✅an individual organism possessing two of the same alleles at a
locus
what is a phenotype or trait - ANS✅✅the appearance or manifestation of a characteristic
what is a characteristic or character - ANS✅✅an attribute or feature possessed by an organism
what were mendel's observations (P gen is homozygous for round seeds (RR) and homozygous for
wrinkled seeds(rr)) - ANS✅✅-F1 hybrids express the dominant phenotype the self fertilized to
create the F2 gen
-F2 plants with the recessive trait reappear
,-in the F2, the ratio of the dominant phenotype to the recessive phenotype is 3:1 then self fertilized
the F2 gen to create the F3 gen
-F3 gen: homo round peas produced plants w only round peas, heater plants produced round seeds
in a 3:1 ratio, homo wrinkled peas produced plants w only wrinkled peas
what is Mendel's law of segregation - ANS✅✅allele pairs separate or segregate during gamete
formation, and randomly unite at fertilization
genes come in pairs so each cell has how many allele of a gene - ANS✅✅two
alleles for a pair of genes can be - ANS✅✅hetero or homo
each gamete contains how many alleles of each gene - ANS✅✅one
union of male and female gametes is ______ and __________ - ANS✅✅-random
-reunites alleles in pairs
what is the principle of segregation (Mendel's first law) - ANS✅✅each individual diploid organism
possesses two alleles for any particular characteristic. these two alleles segregate when gametes are
formed, and one allele goes into each gamete
what is the conception of dominance - ANS✅✅when two different alleles are present in a
genotype, only the trait encoded by one of them-the "dominant allele"- is observed in the
phenotype
a test cross can be used to determine - ANS✅✅whether an organism with a dominant phenotype
is homozygous or heterozygous
explain a dihybrid cross - ANS✅✅-a cross of true-breeding round yellow and wrinkled green
parental strains yields round yellow F1 progeny
-results in an equal frequency of all four possible types of gametes (alleles of two genes segregate
independently)
-independent assortment leads to a 9:3:3:! phenotypic ration in the F2
, describe Mendel's law of independent assortment - ANS✅✅alleles of one gene sort into gametes
independently of the alleles of another gene
comparison of the principles of segregation and independent assortment - ANS✅✅Principle:
Segregation (Mendel's first law) Observation 1) each individual organism possess two alleles
encoding trait. State of meiosis: before meiosis. Observation 2) alleles separate when gametes are
formed. State: anaphase I. Observation 3) alleles separate in equal proportions. State: anaphase I.
Principle: Independent assortment (Mendel's second law) observation) alleles at different loci
separate independently state: anaphase I
the principle of independent assortment results from - ANS✅✅the independent separation of
chromosomes in anaphase I of meiosis
1) the cell contains two pairs of homologous chromsosomes
2) in anaphase I of meiosis, each pair of homologous chromosomes separate independently
3) so geese located on different pairs of chromosomes assort independently, producing different
combinations of alleles in the gametes
to determine the probability of two independent events occurring you - ANS✅✅use the
multiplication rule
to determine the probability of one event with multiple options occurring you - ANS✅✅use the
addition rule
what is a branch diagram - ANS✅✅a forked diagram demonstrating how phenotypic ratios can be
predicted in a trihybrid cross, without resorting to use of a punnett square
if the probability of being blood type A is 1/8 and the probability of being blood type O is 1/2, what is
the probability of being either blood type a or o - ANS✅✅5/8
In cucumbers, dull fruit (D) is dominant over glossy fruit (d), orange fruit (R) is dominant over cream
fruit (r), and bitter cotyledons (B) are dominant over nonbitter cotyledons (b). The three characters
are encoded by genes located on different pairs of chromosomes. A plant homozygous for dull,
orange fruit and bitter cotyledons is crossed with a plant that has glossy, cream fruit and nonbitter
cotyledons. The F1 are intercrossed to produce the F2.
a.Give the phenotypes and their expected proportions in the F2.
answers graded A+
Describe Mendelian genetics - ANS✅✅-true breeding
-self-fertilization
-highly homozygous
-peas
-Mendel picked discrete traits (binary phenotype)
what is a gene - ANS✅✅an inherited factor (encoded in the DNA) that helps determine a
characteristic
what is an allele - ANS✅✅one of two or more alternative forms of a gene
what is a locus - ANS✅✅a specific place on a chromosome occupied by an allele
what is a genotype - ANS✅✅set of alleles possessed by an individual organism
what is a heterozygote - ANS✅✅an individual organism possessing two different alleles at a locus
what is a homozygote - ANS✅✅an individual organism possessing two of the same alleles at a
locus
what is a phenotype or trait - ANS✅✅the appearance or manifestation of a characteristic
what is a characteristic or character - ANS✅✅an attribute or feature possessed by an organism
what were mendel's observations (P gen is homozygous for round seeds (RR) and homozygous for
wrinkled seeds(rr)) - ANS✅✅-F1 hybrids express the dominant phenotype the self fertilized to
create the F2 gen
-F2 plants with the recessive trait reappear
,-in the F2, the ratio of the dominant phenotype to the recessive phenotype is 3:1 then self fertilized
the F2 gen to create the F3 gen
-F3 gen: homo round peas produced plants w only round peas, heater plants produced round seeds
in a 3:1 ratio, homo wrinkled peas produced plants w only wrinkled peas
what is Mendel's law of segregation - ANS✅✅allele pairs separate or segregate during gamete
formation, and randomly unite at fertilization
genes come in pairs so each cell has how many allele of a gene - ANS✅✅two
alleles for a pair of genes can be - ANS✅✅hetero or homo
each gamete contains how many alleles of each gene - ANS✅✅one
union of male and female gametes is ______ and __________ - ANS✅✅-random
-reunites alleles in pairs
what is the principle of segregation (Mendel's first law) - ANS✅✅each individual diploid organism
possesses two alleles for any particular characteristic. these two alleles segregate when gametes are
formed, and one allele goes into each gamete
what is the conception of dominance - ANS✅✅when two different alleles are present in a
genotype, only the trait encoded by one of them-the "dominant allele"- is observed in the
phenotype
a test cross can be used to determine - ANS✅✅whether an organism with a dominant phenotype
is homozygous or heterozygous
explain a dihybrid cross - ANS✅✅-a cross of true-breeding round yellow and wrinkled green
parental strains yields round yellow F1 progeny
-results in an equal frequency of all four possible types of gametes (alleles of two genes segregate
independently)
-independent assortment leads to a 9:3:3:! phenotypic ration in the F2
, describe Mendel's law of independent assortment - ANS✅✅alleles of one gene sort into gametes
independently of the alleles of another gene
comparison of the principles of segregation and independent assortment - ANS✅✅Principle:
Segregation (Mendel's first law) Observation 1) each individual organism possess two alleles
encoding trait. State of meiosis: before meiosis. Observation 2) alleles separate when gametes are
formed. State: anaphase I. Observation 3) alleles separate in equal proportions. State: anaphase I.
Principle: Independent assortment (Mendel's second law) observation) alleles at different loci
separate independently state: anaphase I
the principle of independent assortment results from - ANS✅✅the independent separation of
chromosomes in anaphase I of meiosis
1) the cell contains two pairs of homologous chromsosomes
2) in anaphase I of meiosis, each pair of homologous chromosomes separate independently
3) so geese located on different pairs of chromosomes assort independently, producing different
combinations of alleles in the gametes
to determine the probability of two independent events occurring you - ANS✅✅use the
multiplication rule
to determine the probability of one event with multiple options occurring you - ANS✅✅use the
addition rule
what is a branch diagram - ANS✅✅a forked diagram demonstrating how phenotypic ratios can be
predicted in a trihybrid cross, without resorting to use of a punnett square
if the probability of being blood type A is 1/8 and the probability of being blood type O is 1/2, what is
the probability of being either blood type a or o - ANS✅✅5/8
In cucumbers, dull fruit (D) is dominant over glossy fruit (d), orange fruit (R) is dominant over cream
fruit (r), and bitter cotyledons (B) are dominant over nonbitter cotyledons (b). The three characters
are encoded by genes located on different pairs of chromosomes. A plant homozygous for dull,
orange fruit and bitter cotyledons is crossed with a plant that has glossy, cream fruit and nonbitter
cotyledons. The F1 are intercrossed to produce the F2.
a.Give the phenotypes and their expected proportions in the F2.
