The number of trophic levels in an ecological pyramid a. is limitless. b. is limited by the amount of energy that is lost at each trophic level. c. never exceeds four. d. never exceeds three.

Aresearcher has developed two stains for use with seed plants. one stains sporophyte tissue blue; the other stains gametophyte tissue red. if the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur? a) the pollen grains will be pure red.b) the pollen grains will be pure blue.c) the pollen grains will have red interiors and blue exteriors.d) the pollen grains will have blue interiors and red exteriors.

Which of these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine

Which is the function of the hypothalamus in thermoregulation? answers: -sensor -effector -stimulus -intergrating center it's either a or c i believe