The petal color of a species of flower is inherited along mendelian ratios. A cross of two plants with red flowers produces 1068 plants with red flowers and 390 plants with yellow flowers.
a) PROPOSE a model and explain the inheritance of red and yellow flowers
b) DETERMINE the probability of producing a plant with yellow flowers when a heterozygous plant with red flowers is crossed with a homozygous plant with yellow flowers
a) The inheritance of red and yellow flowers can be explained by a model involving a single gene with two alleles. Let's call the gene "R" for red and "Y" for yellow. Based on the cross, we can deduce that red flowers are dominant (represented by the genotype RR or RY) and yellow flowers are recessive (represented by the genotype YY).
When two plants with red flowers are crossed, they can have the genotypes RR or RY. Both genotypes will result in the phenotype of red flowers. On the other hand, when a plant with yellow flowers (genotype YY) is crossed with a plant with red flowers (genotype RY), there is a 50% chance for the offspring to inherit a yellow flower phenotype. This is because the yellow allele (Y) is recessive and will only be expressed if present in homozygous form (YY).
b) To determine the probability of producing a plant with yellow flowers when a heterozygous plant (genotype RY) is crossed with a homozygous plant with yellow flowers (genotype YY), we can use a Punnett square.
RY x YY
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RY RRYy
RY RRYy
In this cross, each parent contributes one allele to each offspring. The Punnett square shows the possible genotypes and phenotypes of the offspring.
Out of the four possible genotypes, two of them (RRYy) represent plants with red flowers, and the other two (RRyy) represent plants with yellow flowers.
Therefore, the probability of producing a plant with yellow flowers when crossing a heterozygous plant with red flowers (genotype RY) with a homozygous plant with yellow flowers (genotype YY) is 2/4 or 1/2 (50%).