A person with blood group$-A$ has
Antigen$-A$ and Anti$-B$ Antibodies
Antigen$-B$ and Anti$-A$ Antibodies
Both antibodies
No antibody and no antigen
Both sickle cell anaemia and Huntington’s chorea are
In man, albinism is due to non-synthesis of melanin in the absence of
$A $: Non-allosomic genic determination of sex is found in bacteria.
$R$ : Sex is dependent on some environmental factors in prokaryotes.
When the number of recombinant progeny is usually less than the number expected in independent assortment it is called
Crossing over is advantageous because it brings about