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. the relationship between genes s and n is an example . codominance.2. pleiotropy.3. complete dominance.4. epistasis.5. incomplete dominance.

4: epistasis

Explanation:

Epistasis is a form of gene interaction in which a gene on one locus modifies or suppresses the effects of another gene on a separate locus.

Epistatic gene interaction can be dominant, recessive, duplicate recessive, duplicate dominant, or polymeric gene interaction.

In this case, the expression of gene is controlled by the presence/absence of gene N on a separate locus. In homozygous recessive form, gene N suppresses the expression of gene S, a clear case of recessive epistasis.

The correct option is option 4.

i think the answer is g1

hope i

-lavira: )

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.