8. All of the mendelian alleles for different trait showed
(1) Epitasis
(2) Co-dominance
(3) Incomplete dominance
(4) Dominance and recessiveness

Explanation:

In Mendel’s classic pea plant experiments (seed shape, seed color, flower color, pod shape, pod color, flower position, stem length), each trait behaved as if controlled by a single gene with two alleles, where:

• One allele’s effect was fully expressed in heterozygotes (dominant).

• The other allele’s effect was masked in heterozygotes and appeared only in homozygous form (recessive).

This clear dominant–recessive relationship produced the familiar 3:1 monohybrid and 9:3:3:1 dihybrid ratios.

Why the other options are incorrect:

1. Epistasis

• Epistasis is interaction between alleles at different loci (one gene masking another), which modifies Mendelian ratios (e.g., 9:7, 12:3:1). Mendel’s original traits did not show such modified ratios.

2. Co-dominance

• In codominance, both alleles in a heterozygote are fully expressed (e.g., human AB blood group). Mendel’s traits did not show mixed or joint expression; the heterozygote resembled one parent only.

3. Incomplete dominance

• In incomplete dominance, the heterozygote shows an intermediate phenotype (e.g., red × white flowers → pink). Mendel’s pea traits did not behave this way; heterozygotes were indistinguishable from the dominant homozygote.

Thus, “all of the Mendelian alleles for different traits” are characterized by simple dominance and recessiveness, making option (4) correct.