The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

The leopard frog and the pickerel frog are two closely related species. in areas where their ranges overlap, the frogs will remain separate species if they

10. in which phase will crossing-over occur? a. mitosis b. metaphase ii c. prophase i d. meiosis ii

The embryos of a bird, a reptile, and a mammal are similar in appearance. how does comparing the physical appearance of embryos of different species support the theory of evolution? a. it shows that these organisms share a common ancestor. b. it provides evidence that these organisms eat the same foods. c. it shows that these organisms share the same habitat. d. it provides evidence that these organisms suffered a genetic mutation.