The number of linkage groups in $E. coli$ is:

Which of the following is true about linkage?
$I.$ It is a phenomenon in which more recombinants are produced in $F_{2}$-generation.
$II.$ More parental combinations are produced in $F_{2}$-generation.
$III.$ Genotypes which are present in $F_{1}$ hybrid reappear in high frequency in $F_{2}$-generation.
$IV.$ It is a phenomenon in which two chromosomes are linked.

The distance between two linked genes on a chromosome is measured in cross-over units,which is:

There are three genes $a, b, c$. The percentage of crossing over between $a$ and $b$ is $20\%$,between $b$ and $c$ is $28\%$,and between $a$ and $c$ is $8\%$. What is the sequence of genes on the chromosome?

Drosophila melanogaster has $8$ chromosomes in its somatic cell. How many linkage groups will it have?

When linked characters or genes are inherited together through two or more generations,it is called