Final answer:
A recessive trait is expressed only when two identical copies of a gene are present; by contrast, a dominant trait can be expressed with just one copy. Mendel's experiments showed that white flower color is a recessive trait that is masked by the dominant violet color unless two recessive alleles are inherited. In X-linked recessive traits, males are more likely to express the condition, such as red-green color blindness.
Step-by-step explanation:
Understanding Recessive Traits
When a trait is described as recessive, it means that the trait is only expressed when two identical copies of a gene, known as alleles, are present. This condition is referred to as being homozygous for the trait. In contrast, a dominant trait is expressed even when only one copy of the allele is present, which is a condition known as heterozygous. The classic example provided by Mendel's pea plant experiments highlights violet flowers as a dominant trait, whereas white flowers represent a recessive trait.
Within a Punnett square grid, all potential combinations of alleles transmitted by parents to offspring are displayed, allowing the prediction of the mathematical probability of an offspring inheriting a particular genotype. For instance, if both parents carry one recessive allele for a trait, there is a 25% chance that their child will exhibit the recessive trait. This is because the child would need to inherit the recessive allele from both parents to express the trait.
In the context of X-linked traits, recessive conditions are more likely to be expressed in males because they have only one X chromosome. An example is red-green color blindness, which manifests in males if they inherit the recessive allele since they do not have a second X chromosome to potentially carry a dominant allele that could mask the recessive one.