NCEA Level 2 Biology Genetics Practice Exam

In a monohybrid cross involving two heterozygous parents, each parent possesses two alleles for a particular trait—one that is dominant and one that is recessive. When these two parents are crossed, the potential combinations of alleles in the offspring can be predicted using a Punnett square. Each heterozygous parent can contribute either the dominant or recessive allele. The combinations of alleles in the offspring can be represented as follows: - Homozygous dominant (HH) - Heterozygous (Hh) - Heterozygous (Hh) - Homozygous recessive (hh) When you tally these combinations, you end up with three offspring showing the dominant phenotype (two heterozygous and one homozygous dominant) and one showing the recessive phenotype. This leads to a phenotypic ratio of 3:1. This ratio reflects that for every four offspring, approximately three would express the dominant phenotype and one would express the recessive phenotype, which is characteristic of this type of genetic cross. The other ratios presented do not arise from a monohybrid cross of two heterozygous parents, as they reflect different genetic scenarios or crosses involving multiple traits, which are not