Mitotic stages and chromosome morphology:
In Anaphase, the centromere connecting sister chromatids synchronously cleaves/divides, and the spindle fibers contract to pull sister chromatids toward opposite spindle poles.
Because the centromere leads the movement while the chromosome arms trail behind, chromosomes assume characteristic shapes depending on centromere position:

• Metacentric chromosomes: appear distinctly 'V' shaped (two equal arms).
• Sub-metacentric: 'L' shaped.
• Acrocentric: 'J' shaped.
• Telocentric: 'I' shaped.

Modified dihybrid phenotypic ratios in epistasis:
(A) Dominant Epistasis -> (II) 12:3:1: When a dominant allele of one gene masks the expression of both alleles of another gene (e.g., fruit color in summer squash).
(B) Inhibitory Gene Action -> (I) 13:3: When a dominant inhibitor gene suppresses the expression of a dominant allele of another gene (e.g., feather color in fowl, grain color in rice).
(C) Duplicate Epistasis (Duplicate Dominant) -> (III) 15:1: When either of two independent dominant genes produces the phenotype (e.g., shepherd's purse fruit shape, awned vs awnless in rice).
(D) Complementary Gene Action (Duplicate Recessive) -> (IV) 9:7: When dominant alleles of both genes must be present together to produce the phenotype (e.g., flower color in sweet pea).