Question

When HFR conjugates with an $F^-$ bacterium. the
A $F^-$ cell will convert to $F^+$ but always a recombinant
B $F^-$ cell will convert to $F^+$ but always a not recombinant
C $F^-$ Hill remain $F^+$ and may or may not be a recombinant
D $F^-$ will convert to Hfr without recombination

Answer 1

Hint: High frequency recombination (Hfr) bacteria are those that have their $F^-$ plasmid (sex factor) integrated with their chromosomal DNA. The frequency of recombination is quite high in the cross (conjugation) between Hfr cells and $F^-$ cells, but the frequency of transfer of the entire $F^-$ factor is relatively low.

Complete answer:
High-frequency recombination cells are abbreviated as HFR. HFR cells are those in which the plasmid has been incorporated into the chromosomal DNA. As a result, when bacteria conjugate with $F^-$ cells using $F^-$ plasmid genes, the genes that are closer to the F cells are also transferred to the $F^-$ cells.
This would result in the F cells forming a partly diploid state, as they may have two sets of some genes. As a result, recombination between homologous genes may be possible in these cells. As a result, the right response is '$F^-$ cell will convert to $F^+$, but it will always be a recombinant'.

So option A is the correct answer.

Note:
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or a bridge-like link. This is accomplished through the use of a pilus. In bacteria, it is a parasexual way of reproduction. It, like transformation and transduction, is a horizontal gene transfer method, however these two do not involve cell-to-cell contact.