Early cells likely formed from a group of organic compounds, including proteins, and primitive fatty acids. why do most scientists think that the first true cells formed on earth were anaerobic? a. because they could produce their own oxygen
b. because there was no oxygen on early earth
c. because they make their own food
d. because they use less energy to find nutrients

Imagine a person stepping on a pin and pulling his or her foot away. look at the reflex arc of this scenario below. which statement best describes the image? a)the sensory nerve carries the signal from the effector to the interneuron, and the motor neuron carries the signal to the receptor. b)the motor nerve carries the signal from the receptor to the interneuron, and the sensory neuron carries the signal to the effector. c)the sensory nerve carries the signal from the receptor to the interneuron, and the motor neuron carries the signal to the effector. d)the sensory nerve carries the signal from the receptor to the motor neuron, and the interneuron carries the signal to the effector.