15. which of the following is not an accurate description of chemical reactions? a. the rates of chemical reactions can vary. b. chemical reactions that take in energy never need a source of energy to start. c. during chemical reactions, energy can be released or used up. d. during chemical reactions, bonds can be broken or formed.

Which of the following is the most likely result of converting forestland to urban development? a.the amount of land available for lumber production decreases. b.fewer trees are needed because cities are made mainly of concrete. c.people discover more efficient ways to grow trees. d. the price of lumber goes down.

What is the mrna strand that would be copied from this dna strand

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.