Why are only two phenotypes possible?

The phenotype is the physical manifestation of an organism's allellic combination (genotype). For the pea plants, if the red allele is dominant and the white allele is recessive, only two phenotypes are possible. ... Often, organisms will carry a dominant and a recessive allele of a gene.

Explanation:

there are mainly three domains in biological classification namely; archaea, bacteria, and eukarya.

archaea includes all the prokaryotic cells which are characterized by their lipid membranes. they have branched hydrocarbon which is attached to glycerol through an ether linkage.

bacteria includes all the prokaryotic cells, the cell membrane of which are made up of the unbranched fatty acid chain. in addition, they are attached to glycerol through an ester bond.

eukarya includes all the eukaryotic cells, that is, the cells contain a nucleus and other membrane-bound cell organelles.

they can be autotrophic as well as heterotrophic, unicellular as well as multicellular

they include kingdoms like protista, plantae, animalia, fungi et cetera.

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explanation: