Which species is more primitive lungfish or frogs?

 lungfish

Explanation:

Several million years ago, life is thought to have evolved from a common aquatic ancestor. This organism is thought to have developed a new means of gaseous exchange that would allow its descendants to eventually develop the ability to move about, and live  solely on land. This new means of gas exchange were lungs.

While frogs are sometimes land-dwelling, these amphibians are thought to have developed from an aquatic-dwelling species that adapted to a mostly wet land environment. Frogs, like most land dwellers, are tetrapods, with four distinct limbs.

Lungfish, however, have gills, along with primitive lungs for gas exchange. Along with four modified fins, these organisms have the appearance of an intermediary- they are thought to show the evolutionary leap from aquatic to terrestrial life.

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.

1. dermis

2. chemical

3. urine

4. viruses

5. antibodies