On Thursday, we talked about movement and whether or not it was an indication of life. As a class, we remembered that airplanes, waterfalls, and cars aren't alive, even though they move. Before we move on, think about this, and see if you can come up with an answer:

A biologist from another galaxy might think that automobiles are a dominant form of life on planet Earth. Automobiles move, consume gasoline and oil, and produce wastes. They are sheltered in garages and respond to stimuli. Automobiles age and break down, but new automobiles appear each year. They evolve, changing in appearance from year to year. What arguments would you use to persuade the alien visitor that cars are not alive?

Paramecium obtain their own food from the external environment, They are covered with short, hairlike substances called cillia that are used both for movement and to sweep food into a tiny groove that is similar to a mouth.

Stentor and some other unicellular organisms produce stalks to attach themselves to the bottom of ponds and streams. Stentor, like paramecium, have cillia, but these structures are used to bring in food rather than for movement.

Living balls made of many volvox live together as a colony. Each has its own flagellum and makes its own food by photosynthesizing.

Nucleus

Endoplasmic Reticulum

Cytoplasm

Mitochondria

Cell membrane

Vacuoles