How the immune system works, explain why injecting an
antigen from a pathogen would help our immune
system create "memory" of the infection but not
cause the disease.

{answer found. it's (3 ) }which statement describes the cell cycle? (1)the cell cycle is a process in which one cell divides into four genetically different cells. (2)the cell cycle is a process in which one cell divides into two genetically different cells. (3)the cell cycle is a process in which one cell divides into two genetically identical cells. (4)the cell cycle is a process in which one cell divides into four genetically identical cells.

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land