Students are each given a 20-gram sanple of an unknown solid compound in a clear plastic bag. They are instructed to break the material into smaller parts by gently hitting it with a hammer. Some of the parts break into large chunks and
some look like a fine powder.
Which statement correctly describes these broken pieces of the sample?
O The fine powder pieces are individual atons broken from the solid.
O The larger pieces are still compounds and the smaller pieces are elements.
O Each piece contains the same number of atoms.
O Each piece contains the same proportion of different elements.

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.

Suppose you have monohybrid pea plants in your garden and find that they produce round seed to wrinkled seeds in the ratio of 3: 1. if the allele are designated (r & r) receptively. what is the probable genotypes of the round seeds which produced f 1 ? rr & rr rr only rr & rr rr only rr only

Which of the follow describes a disadvantage secondary sources have compared to primary sources?