Solution

Epistatic gene: In genetics, a gene that determines whether or not a trait will be expressed. The system of genes that determines skin colour in man, for example, is independent of the gene responsible for albinism (lack of pigment) or the development of skin colour. This gene is an epistatic gene. When the albino condition occurs, the genes that determine skin colour are present but not expressed.

Dominant gene: The first allele is dominant and the second allele is recessive. For genes on an autosome (any chromosome other than a sex chromosome), the alleles and their associated traits are autosomal dominant or autosomal recessive.

Epistatic gene is non-allelic. Epistatic gene never express itself independently. Epistatic and hypostatic genes are present at different loci.

Solution

Starfish belongs to the group of echinoderm. Echinoderm have unique vascular water system.
This system opens to the exterior through a sieve-like madreporite on the aboral surface of the animal. The madreporite is linked to a slender duct called the stone canal.
This canal extends to a ring canal that encircles the mouth or oesophagus. From this, radial canals extend along the arms. Short lateral canals branch off the radial canals, each one ending in an ampulla. Part of the ampulla can protrude through a pore to the exterior and is known as a podium or tube feet. Osphradium is an olfactory organ present in certain molluscs.

The lymphatic system not only regulates fluid amounts in the blood but also helps to fight infection.

The lymph nodes located throughout our bodies, produce white blood cells and filter harmful bacteria, which is why they tend to enlarge when we have an infection