What role did gravity play in the formation of earth

Ascientist is studying muscle twitches in chicken quadriceps. to activate the muscle, he needs to provide stimulus to the

Jason adds the antibiotic penicillin to a bacterial culture. the bacteria develop genetic modifications in their genome, which gives them resistance to the antibiotic penicillin. what caused this genetic modification?

If jane has the blood type ab and marries john who has type o blood what are the possible phenotypes of their first kid?