Throughout the night, the human body is exposed to various molds, bacteria, and viruses. yet, in the morning, the human body is left unharmed. what is the human body's first defense against infection from these threats?

a. the skin produces cells that both detect and kill antigens.
b. the skin sheds old skin hourly to ensure newly regenerated skin.
c. the immune system produces t-killer and t- cells at night.
d. the immune system overly produces antibodies as one sleeps.

Which taxon group is more specific, in regards to organisms that are in that group? mammalia animalia

Maria wanted to grow a fern in her backyard. acting on a suggestion from a friend, she collected brown dots from the underside of a fern's leaves and then potted them. after a few days, maria saw small fern leaves erupting from the pot. which statement explains this phenomenon? a. the fern transitioned from gametophyte generation to sporophyte generation. b. the fern grew as a result of mitosis. c. the fern transitioned from sporophyte generation to gametophyte generation. d. the fern grew to be genetically identical to its parent plant.

What did hunter gathers do to alter the environment?