humans have bones and muscles that us move. what structure protects insects and gives them structure?
a. skin
b. rigid tubes
c. exoskeleton
d. other muscles

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

The spermists believed that: the male made the only hereditary contribution to the offspring the male and female traits were blended in the offspring the female made the only hereditary contribution to the offspring the male and the female made equal contributions to the next generation

List five ways we are indebted to phytoplankton