Explain why a paramecium would require contractile vacuoles while a similar protozoan living in salt water would not.

Aneuron is stimulated with an electric pulse. the action potential is detected at a point 3.70 cm down the axon 0.0052 s later.when the action potential is detected 7.20 cm from the point of stimulation, the time required is 0.0063 s. what is the speed of the electric pulse along the axon? (why are two measurements needed instead of only one? )

Which of the following lines of evidence would best support your assertion that a particular plant is an angiosperm? a) it produces seeds. b) it retains its fertilized egg within its archaegonium. c) it lacks gametangia. d) it undergoes alternation of generations.

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.