In humans, the yolk sac in humans, the yolk sac is the site of origin for blood cells and primordial germ cells is no longer a useful structure forms the human urinary bladder passes nutrients to the embryo after digesting the yolk mass

Getting rid of my account might as well do it with some fun make sure to read all of this it is hilarious a plane was about to crash and there were 5 people on board and only 4 parachutes. the first person said: " i am roy keane, one of the best footballers in ireland. i am worth a lot of money and my fans need me so i think i should be saved." the others agreed and gave him one of the parachutes and off he went. the second person said: "i am gerry adams, a radical irish politician who can really my country and i think i should be saved." the others said: "o.k.", and gave him a parachute. the third person said: "i am george bush, president of the most powerful country in the world. everyone knows i am a really nice guy and everyone thinks i am stupid,but i'm not, so i am taking a parachute." and off he went. there were two people left, the pope and a 10 year old schoolgirl. the pope said: "child, i am old and frail and have lived my life while you are young, with everything before you. you take the parachute and i will stay with the aircraft and take my chance." "it's o.k." said the girl, "there are still two bush picked up my schoolbag."

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point