Acertain species of rabbit can have either black or grey fur. the allele for black fur is dominant over the allele for grey fur. if a homozygous black rabbit is crossed with a heterozygous black rabbit, what phenotypic ratio will occur in the first generation? a. 50% black : 50% grey b. 25% black : 75% grey c. 100% black : 0% grey d. 75% black : 25% grey

When completing a Punnett Square, letters are used to designate the alleles involved. The question states that white fur is dominant to black fur. Therefore, "W" will represent the dominant white allele and "w" will represent the black fur. The only genotype that will represent a black furred bunny would be "ww" (homozygous recessive). However, the homozygous dominant (WW) or heterozygous (Ww) genotypes both code for white fur. Yet, since some black bunnies are produced, the white furred bunny must be heterozygous. Thus, the following Punnett Square would be applied:

          w                  w

W       Ww               Ww

w      ww                 ww

Phenotype frequencies:

50% white

50% black

Genotype frequencies:

50% heterozygous

50% homozygous recessive

b ti isnfornopgnoernfrof

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.