In response to a stimulus, a brain cell called a neuron will send a signal to the brain

a. respiration and absorption
b. myosin and actin
c. electrical signals and chemical neurotransmitters
d. contraction and relaxation

Which of these statements best describes the st. lawrence seaway? the st. lawrence seaway connects the st. lawrence river with the arctic ocean. the st. lawrence seaway provides an important trading route between the u.s. and mexico. the st. lawrence seaway provides an important trading route for the u.s, but has little value for canada. the st. lawrence seaway connects the great lakes, the st. lawrence river, and the atlantic ocean.

The most famous fossil called archaeopteryx is which of the following? a dinosaur a fern a fish a bird

The ultimate purpose of respiration: a. inhale 02 and exhale co2 b. place oxygen in the lungs c. place oxygen in the blood d. deliver oxygen to every blood cell