Final answer:
Gene linkage occurs when genes on the same chromosome are transmitted together instead of independently. Recombination or crossover events can break this linkage and allow genes on the same chromosome to behave independently.
Step-by-step explanation:
When genes on the same chromosome are not transmitted under the laws of independent assortment, but instead are transmitted as a unit, this is known as gene linkage.
Gene linkage occurs when genes are located in close proximity on the same chromosome, causing their alleles to be inherited together. However, recombination or crossover events can break this linkage, allowing genes on the same chromosome to behave independently.
For example, if two genes for flower color and plant height are on the same chromosome, alleles for tall plants and red flowers may tend to go together into a gamete, while alleles for short plants and yellow flowers may go into other gametes.
However, the distance between the genes on the chromosome affects the probability of crossovers, making the genes behave more like they are on separate chromosomes.