The Living World

Louis Pasteur and Edward Jenner

The three lines of defense in the immune system are the physical and chemical barriers, the innate immune response, and the adaptive immune response.

A pandemic is an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population.

<p>Infectious diseases are caused by pathogens, such as bacteria or viruses, and can be transmitted from person to person. Non-infectious diseases are not caused by pathogens and cannot be transmitted from person to person.</p> Signup and view all the answers

<p>The three types of organisms in an ecosystem are producers, consumers, and decomposers. Producers, such as plants, produce food through photosynthesis. Consumers, such as animals, obtain energy by consuming other organisms. Decomposers, such as bacteria and fungi, break down dead organisms and recycle nutrients.</p> Signup and view all the answers

<p>Steady state theory</p> Signup and view all the answers

<p>Radioisotope dating</p> Signup and view all the answers

<p>Radio waves</p> Signup and view all the answers

<p>Plate tectonics</p> Signup and view all the answers