21. The diagram below represents a sequence of events that occurs in living things. х
are digested into
Smaller molecules
which can be synthesized into
Fat
Starch
Protein
DNA
Letter X represents
Inorganic molecules
O organic molecules
O biological catalysts
O simple sugars

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.

20 points and brainlist 1. london has suffered from terrible air pollution for at least seven centuries. why is the city so prone to its famous “london fog? ” what did london do to get rid of its air pollution? 2. why does air pollution cause problems in developing nations more than in developed ones?

Paint and solvents pose no potential hazard to human health. select the best answer from the choices provided t f