In response to a stimulus a brain cell called a neuron will send a signal to the brain using
a). electrical signals and chemical neurotransmitters
b). myosin and actin
c). contraction and relaxation
d). respiration and absorption

Which member of the following food chain will be least affected by ddt, a pesticide water pollutant, if bio-magnification is occurring? algae> zooplankton> crayfish> leopard frog> large mouth bass

Which of the following is likely not involved in this example of ecological succession? a) the rotting remains of plants add to the fertility of the soil. b)the soil becomes so fertile that eel grass is replaced by other plant species. c) the roots from plants stabilize the sediment, keeping it in place. d) the concentration of salt becomes so high that all plant life is destroyed.

What does the number 18.9984 represent in the image?