Q.Which of the following sentences are correct?

1. The offspring exhibit only parental combinations due to incomplete linkage
2. The linked genes exhibit some crossing over in complete linkage
3. The separation of two linked genes are possible in incomplete linkage
4. Crossing over is absent in complete linkage

Linkage is the tendency of genes located close together on the same chromosome to be inherited together, as a single physical unit, rather than assorting independently the way genes on separate chromosomes do. Because crossing over between two tightly linked genes during meiosis is rare, most gametes carry the original (parental) combination of alleles, and only a small fraction carry a new recombinant combination produced by an actual crossover event - so tightly linked genes show very few recombinant offspring, while genes located far apart on the same chromosome, where crossing over is more frequent, approach the recombination frequency expected of fully independent genes. This effect shows up experimentally in a dihybri …