An ecosystem that is not sustainable can break down when a natural diaster occurs. This can lead to organisms in the ecosystem either leaving the area or dying off. Increased biodiversity results in a more substainable ecosystem because-

a there are fewer species to be affected by environmental stresses
b a greater variety of species present allows more organisms to adapt after changes occur
c the transition are between two ecosystems in narrower
d a greater number of plants species means that there is less barren land

Which of the following is a macronutrient? carbohydrates lipids amino acids all of the above

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.

Which is the correct order in the scientific process? ask a question ® form a hypothesis ® make an observation ask a question ® make an observation ® form a hypothesis make an observation ® form a hypothesis ® ask a question make an observation ® ask a question ® form a hypothesis