The reason for fault in gene duplication is

$...$ is a phenomenon by which genetic variation is achieved through changes in the base sequences within genes,which creates a new character or trait absent in the parental generation.

Hugo de Vries proposed the Mutation theory by studying the plant called . . . . . . .

The sixth mutant codon of the beta globin gene causing polymerization of haemoglobin and change in $RBC$ shape is . . . . . . .

Which of the following agents causes mutations by deamination?

Match the columns:

Column-$I$	Column-$II$
$(1)$ Lethal mutation	$(a)$ Mutation caused by external factors
$(2)$ Spontaneous mutation	$(b)$ They are metabolic errors
$(3)$ Induced mutation	$(c)$ As a result the mutant dies
$(4)$ Biochemical mutation	$(d)$ Most of the mutations occurring in nature are of this type