Question

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce ________.

Answer 1

Answer:

Sharp-spined cactus

Explanation:

Given, that N allele is required for the production of spine and S allele will produce sharp sines.

True breeding sharp spined cactus: NNSS

spineless cactus: nn__ ( we can't fix the allele for second gene since it has not been mentioned as true breeding )

Their progeny: NNSS X nn__ = NnS_

So the progeny is going to be sharp spined because both the dominant alleles N and S are present.