6. HIV, the virus that causes AIDS, attacks Helper T cells. These cells are part of which system?

Crinoids, also known as sea lilies, appear to be sea plants but are not plants at all. crinoids are an echinoderm species which uses anchoring structures called holdfasts to attach themselves to the sea floor. crinoids were most abundant in pennsylvania during the mississippian period, which ranged from 375 to 320 million years ago. fossils of the crinoids shows that during most of this time pennsylvania was that provided favorable conditions for crinoid growth. a) glacial terrain b) a dry and sandy plain c) mostly mountain ranges d) covered by warm, shallow seas

Forensic scientists think they know the identity of a skeleton. what rule should they use to select a relative whose dna could be used to try to confirm the identity?

Trees with light brown bark dominate an ecosystem the ecosystem has populations of insects that thrive on the tree bark over time some insect species developed certain physical characteristics that them thrive on the tree bark these physical characteristics also the insects defend themselves from predators which insect species is probaly the species with the new physical characteristics?