Genetics Answers

What is the difference between and exon and an intron?

Definition of mendalslaw, monohybridcrossing,dihybridcrossing

punot squares incomplete dominance cod inaction

multiple allele

Baldness(HB) is dominant in males but recessive in females. The normal gene (Hn)

is dominant in females, but is recessive in males. Explain how a bald offspring can be produced from the mating of normal female with a normal male. Could these parents ever produce a bald girl? Explain.

 In a certain species of plants, scented and odourless flowers occur, together with hairy and smooth stems. A scented, smooth-stemmed plant was crossed with a fully homozygous odourless plant with hairy stems. Indicate the possible genotypes and phenotypes of the parents and offspring that would produce four kinds of phenotypes among the offspring, in equal numbers (1:1:1:1). Assume scented and smooth are dominant. 

In pea plants, tall plants are dominant over dwarf plants and yellow seed coats are dominant over green seed coats.

a. Complete a punnett square for a cross with a pure-breed tall pea plant that produces yellow seeds and a dwarf pea plant that produces green seeds.  List the phenotypic ratio.

b. What would the phenotypic ratios be if you crossed two individuals of the F₁ generation?  

In a certain species of grasshoppers, the gene(R) for red eyes is dominant to the gene for green eyes(r) and is an autosomal trait. The gene for straight wings(S) is dominant to the gene for curly wings(s) and is sex-linked.  The genes are carried on different chromosomes. State the phenotypic ratio of the F1 and F2 if the P1 generation female is homozygous dominant for both traits and the male has green eyes with curly wings.  

In drosophila, there is a dominance hierarchy for wing shape.(Curly>Straight>Wavy>Dwarfed).

Show all work including a legend

a.  State the phenotypic ratio from a cross with heterozygous wavy winged male with a dwarf winged female.  

b.  State the phenotypic ratio from a cross with a heterozygous curly winged male who had a dwarfed winged mother, and a straight winged female whose mother was homozygous with wavy  wings.

In drosophila, there is a dominance hierarchy for wing shape.(Curly>Straight>Wavy>Dwarfed).

Show all work including a legend

a.  State the phenotypic ratio from a cross with heterozygous wavy winged male with a dwarf winged female.  

Baldness(H^B) is dominant in males but recessive in females.  The normal gene (Hⁿ)

is dominant in females, but is recessive in males.  Explain how a bald offspring can be produced from the mating of normal female with a normal male.  Could these parents ever produce a bald girl?  Explain

When a homozygous tall plant with red flowers is crossed with a short plant bearing white flowers, what will the phenotypes of the offspring be for the next two generations?  Indicate the crosses fully showing the genotypes of the P₁and P₂ generations, the gametes, and the F₁ and F₂ offspring.  Note: In this species, tallness (T) is dominant to shortness (t).  A red (R¹) flower is crossed with a white flower (R²) flower produces pink (R¹R²) flowers.