The most accepted theory regarding the make-up of living things is the
organismal theory
cell theory
chromosomal theory

The most accepted theory regarding the make-up of living things is the cell theory.

It was proposed by German scientists Theodor Schwan, Mathias Schleiden and Rudolf Virchow.

It states that;

1. All living organisms are made of cells.

2. The cell is the basic unit of life.

3. Cells arise from pre-existing cells.

in addition the modern version of the cell theory states:

4. Energy flow occurs within cells

5. Heredity information (DNA) is passed from cell to cell.

6. All cells have the same basic chemical composition.

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.