Among many new features found in the early vertebrates, one involved the development in the circulatory system of a ventral chambered [answer1], and cells for transporting oxygen in the blood called [answer2]

Class Insecta is the largest class in the world’s largest phylum  

Pheromones are chemicals produced by one individual that affect the behavior or physiological processes of another individual or individuals.

The Echinoderms are one of two groups of organisms whose anus develops before the mouth in the embryo. What is the other group?

The exoskeleton of the arthropods is more efficient in its use of building materials than the endoskeleton of vertebrates

Which of the following groupings of fishes have cartilaginous skeletons?

Water flows through fish gills in a fashion such that the maximum amount of oxygen can be extracted from the water. In principle, there needs to be a sufficient oxygen concentration gradient between water and blood vessels for the blood to be able to take up oxygen.  To do this, the water flow is in the opposite direction of blood flow.  This arrangement is called _________________?

Arthropods are found in all habitats except in freshwater

The Nyquist plot is a plot of:

The Nyquist Criterion determines closed-loop stability by examining: