Dark energy has been hypothesized to exist in order to explain:

Adigestive system that is a series of tubes beginning at the mouth and ending at the anus is a digestive system.

Lucia is walking barefoot in her yard. she accidentally steps on a nail. how will her nervous system work to generate a reaction? arrange the eventschronologically.

The wings of insects, birds, and bats evolved independently but carry out similar functions. this is an example of a. analogous structures. b. embryonic structures. c. vestigial structures. d. homologous structures.