The heart’s internal pacemaker beats by:
an internal implant that sends an electrical impulse through the heart
the excitation of cardiac muscle cells at the sinoatrial node followed by the atrioventricular node
the excitation of cardiac muscle cells at the atrioventricular node followed by the sinoatrial node
the action of the sinus

The population of bacteria in a petri dish doubles every 40 seconds. the population of the bacteria is initially 400 organisms. what unit is most appropriate for the time at which the number of bacteria is 300? hour bacteria per hour second bacteria per second

What does all of the organ system in a human form

Indicate whether the following statements about the biases in the fossil record are true or false. a) inland species are more likely to be preserved than marine species b) organisms with hard body parts are more likely to be preserved than are those composed soft tissues. c) species that existed over a larger area are more likely to be preserved than species existing over a smaller area. d) organisms that lived very long ago are more likely to be found as fossils than organisms that lived relatively recently e) the fossils of larger organisms are more likely to be found than the fossils of smaller organisms