Final answer:
In a genetic cross between a heterozygous (Pp) and a homozygous dominant (PP) individual, the genotype that belongs in space B of the Punnett square is PP (homozygous dominant). Hence option A is correct.
Step-by-step explanation:
The question is about predicting the genotype of offspring resulting from a cross between a heterozygous and a homozygous dominant individual for a particular trait. This scenario can be analyzed using a Punnett square, a tool developed by the geneticist Reginald Punnett to predict the outcomes of genetic crosses. In this case, the heterozygous parent (Pp) can pass along either the dominant 'P' allele or the recessive 'p' allele, while the homozygous dominant parent (PP) can only pass along the dominant 'P' allele. The Punnett square shows all possible combinations of these alleles. When these combinations are made, the resulting genotypes can include PP (homozygous dominant) and Pp (heterozygous). The genotype PP appears when both dominant alleles are inherited, one from each parent.
Mendel's experiments with pea plants are a classic example of this kind of genetic cross. The dominant allele for yellow seeds, represented by 'Y', and the recessive allele for green seeds, represented by 'y', were crossed to produce offspring with different genotype combinations. Homozygous organisms have two identical alleles (YY or yy), while heterozygous organisms have one of each allele (Yy). Through the random process of fertilization, a Punnett square enables the determination of the genotypic and phenotypic ratios of offspring.
Returning to the student's question, the genotype that belongs in space B of the described Punnett square involving a heterozygous (Pp) and a homozygous dominant (PP) parent is PP (homozygous dominant), since only the dominant 'P' allele from each parent can combine in that particular square.Hence option A is correct.
complete question
A parent that is heterozygous for the trait is crossed with a parent that is homozygous dominant for the traits shown in the punnet square. Which genotype belongs in space B?
a PP
b Рp
c PPP
d Ppp