DIHYBRID

What are DIHYBRID and details complete information 2021

After thoroughly studying each trait separately, Mendle decided to study the inheritance of two traits simultaneously, eg. seed shape could be round wrinkled similarly seed color could be yellow and green he crossed true-breeding round and yellow seed plants with true-breeding wrinkled and green seed plants.

All the F1 one dihybrid were yellow seeded due to dominance. Then he made a dihybrid cross by allowing self-fertilization among F1 dihybrid. This result was quite surprising. Seed produce as F2 progeny were not only in two parental combinations i. e round yellow and wrinkled yellow. A clear 9:3:3:1 phenotypic ratio was found in F2.

2.APPEARANCE OF DIHYBRID

The appearance of these new recombinant phenotypes F2is indicated. A occurred during gametes formation.
Mendel inferred the mechanism of this shuffling as an independent assortment of alleles into gametes.
He concluded that the alleles for seed shapes and color were not bound to remain in parental combination forever i.e with ‘y’ and ‘with ‘y’; rather these were free to assort independently.

R could go with Y or yin any gametes with equal chance. Similarly, r could go with Y or y in any gametes with equal to probability. From types of gametes,i.e RY, Ry, and were formed in equal numbers into a perfect ratio of 1:1:1.
When these gametes randomly fertilized each other, a 9:3:3:1 phenotypic ratio was produced among F2 progeny.

3.WORK SHEET OF DIHYBRID

dihybrid
dihybrid

Name: ______________ Period: _ Date: _________
Chapter 10: Dihybrid Cross Worksheet
In rabbits, gray hair is dominant to white hair. Also in rabbits, black eyes are dominant to red eyes. These letters
represent the genotypes of the rabbits:

  1. What are the phenotypes (descriptions) of rabbits that have the following genotypes?
    Ggbb grey hair,red eyes ggBB white hair,black eyes
    ggbb white hair,red eyes GgBb grey hair,black ayes
  2. A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb the square is set up
    below. Fill it out and determine the phenotypes and proportions in the offspring.
    How many out of 16 have gray fur and
    black eyes? 8
    How many out of 16 have gray fur and red
    eyes? 8
    How many out of 16 have white fur and
    black eyes? 0
    How many out of 16 have white fur and
    red eyes0
  3. A male rabbit with the genotype GgBb is crossed with a female rabbit with the genotype GgBb The
    square is set up below. Fill it out and determine the phenotypes and proportions of offspring
    How many out of 16 have gray fur and
    black eyes? 9
    How many out of 16 have gray fur and red
    eyes? 3
    How many out of 16 have white fur and
    black eyes? 3
    How many out of 16 have white fur and
    red eyes? 1
  4. Show the cross between a ggBb and a GGBb. You’ll have to set this one up yourself:
    Punnett Square:
  5. An aquatic arthropod called a Cyclops has antennae that are either smooth or barbed. The allele for
    barbs (B) is dominant over smooth (bb). In the same organism Non-resistance to pesticides (N) is dominant
    over resistance to pesticides (nn). Make a “key” to show all the possible genotypes (and phenotypes) of this
    organism.
    Genotype Phenotype
    BB
    Bb
    bb
    NN
    Nn
    nn
  6. A Cyclops that is resistant to pesticides and has smooth antennae is crossed with one that is
    heterozygous for both traits. Show the genotypes of the parents.
    Nn x Bb
  7. Set up a punnett square for the cross.
  8. What are the phenotypic ratios of the offspring?
    DiHybrid Practice Problems
  9. In man, assume that spotted skin (S) is dominant over non-spotted skin (s) and that
    wooly hair (W) is dominant over non-wooly hair (w). Cross a marriage between a
    heterozygous spotted, non-wooly man with a heterozygous wooly-haired, non-spotted
    woman. Give genotypic and phenotypic ratios of offspring.
  10. In horses, black is dependent upon a dominant gene, B, and chestnut upon its recessive
    allele, b. The trotting gait is due to a dominant gene, T, the pacing gait to its recessive
    allele, t. If a homozygous black pacer is mated to a homozygous chestnut trotter, what will
    be the appearance of the F1 generation?
  11. In summer squash, white fruit color (W) is dominant over yellow fruit color (w) and disk shaped fruit (D) is dominant over sphere-shaped fruit (d).. If a squash plant true-breeding for
    white, disk-shaped fruit is crossed with a plant true-breeding for yellow, sphere-shaped fruit,
  12. In mice, the ability to run normally is a dominant trait. Mice with this trait are called
    running mice (R). The recessive trait causes mice to run in circles only. Mice with this trait
    are called waltzing mice (r). Hair color is also inherited in mice. Black hair (B) is dominant
    over brown hair (b).For each of the following problems, determine the parent genotypes,
    determine possible gametes then construct a Punnet square to solve.
    a. Cross a heterozygous running, heterozygous black mouse with a homozygous running,
    homozygous black mouse
    Parental genotypes brown mouse
    Possible gametes brown mouse
    Offspring phenotypic ratio black mouse
    b. Cross a homozygous running, homozygous black mouse with a heterozygous running,
    brown mouse
    Parental genotypes brown mouse
    Possible gametes brown mouse
    Offspring phenotypic ratio black mouse
    c. Cross a waltzing brown mouse with a waltzing brown mouse
    Parental genotypes black mouse
    Possible gametes black mouse
    Offspring phenotypic ratio brown mouse
    d. Cross a homozygous running, heterozygous black mouse with a waltzing brown mouse
    Parental genotypes brown mouse
    Possible gametes black mouse
    Offspring phenotypic ratio grey mouse
    e. Cross a heterozygous running, brown mouse with a heterozygous running, homozygous
    black mouse
    Parental genotypes grey mouse
    Possible gametes black mouse
    Offspring phenotypic ratio brown mouse
    f. Cross a heterozygous running, heterozygous black mouse with a heterozygous running,
    heterozygous black mouse
    Parental genotypes black mouse
    Possible gametes black mouse
    Offspring phenotypic ratio black mouse
    1.Set up a punnett square using the following information:
    • Dominate allele for tall plants = D
    • Recessive allele for dwarf plants = d
    • Dominate allele for purple flowers = W
    • Recessive allele for white flowers = w
    • Cross a homozygous dominate parent
    (DDWW) with a homozygous recessive parent
    (ddww)
  13. Using the punnett square in question #1:
    a. What is the probability of producing tall plants with
    purple flowers?
    Possible genotype(s)?
    b. What is the probability of producing dwarf plants
    with white flowers?
    Possible genotype(s)?
    c. What is the probability of producing tall plants with
    white flowers?
    Possible genotype(s)?
    d. What is the probability of producing dwarf plants
    with purple flowers?
    Possible genotype(s)?
  14. Set up a punnett square using the following
    information:
    • Dominate allele for black fur in guinea pigs = B
    • Recessive allele for white fur in guinea pigs =b
    • Dominate allele for rough fur in guinea pigs =R
    • Recessive allele for smooth fur in guinea pigs = r
    • Cross a heterozygous parent (BbRr) with a
    heterozygous parent (BbRr)
  15. Using the punnett square in question #3:
    a. What is the probability of producing guinea
    pigs with black, rough fur?
    Possible genotype(s)?
    b. What is the probability of producing guinea
    pigs with black, smooth fur?
    Possible genotype(s)?
    c. What is the probability of producing guinea
    pigs with white, rough fur?
    Possible genotype(s)?
    d. What is the probability of producing guinea
    pigs with white, smooth fur?
    Possible genotype(s)?

From types of gametes,i.e RY, Ry,try, and ry were formed in equal numbers into a perfect ratio of 1:1:1.
When these gametes randomly fertilized each other, a 9:3:3:1 phenotypic ratio was produced among F2 progeny.

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