Which of the following is true? a) around 1500ad, the human population began to decrease. b)around 1500ad, the human population began to reach carrying capacity. c)around 1500ad, the human population began growing more rapidly. d) around 1500ad, the human population began to level off.

Which element is found in both dna and proteins

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.

What type of organism is a one-celled organism that functions as a single unit? a. bi-celled b. single-celled c. pre-celled d. multi-celled