Fill in the sentences to complete the statements about meiosis. The process of meiosis occurs during the BLANK and results in BLANK.

To maintain the correct number of chromosomes in offspring, male and female gametes contain BLANK of chromosomes as somatic cells.

During fertilization, gametes fuse to form a BLANK cell called a zygote.

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.