Today is Friday (!), September 4 th, 2015 Pre-Class: What makes something alive? Can you come up with a list of qualities a living thing must have in order to be alive? Be prepared for an informal discussion. Having trouble? Try this: Convince me that a rock is not alive. In This Lesson: Characteristics of Life (Lesson 3 of 4)
Today’s Agenda Get a life… …characteristics list. Where is this in my book? – Academic: P. 17 and following… – Honors: P. 4-5
By the end of this lesson… You should be able to assess the living or non- living nature of an object based on set criteria.
Introducing… Let’s do two introductory activity-like things: – Das Rad – Identifying Life Activity
Das Rad German Short Film Things to think about: – What’s alive in the film? What is just “fictionally alive?” – What’s not alive in the film? – What’s the difference?
Being alive… There’s a lot of weird stuff out there. Biologists have settled on eight characteristics that something must have in order to be considered alive. Important: – It must have all eight. – Only seven? Too bad. Not alive.
#1: Made of Cells All living things are made of cells. – Unicellular beings have only one cell. – Multicellular beings have more than one cell.
#2: Can Reproduce Reproduction can be asexual (one parent) or sexual (two parents).
#3: Has Genetic Code DNA (or sometimes other forms) is found in almost every cell and ultimately controls your traits.
#4: Grow and Develop All living things develop and grow during their lives (at least part of ‘em). That’s why we don’t look like big overgrown babies. We look like adults…most of us…
#5: Need Materials/Energy All living things need some kind of food or energy source.
#6: Respond to Stimuli Organisms respond to stimuli (signals either from their bodies or the environment). – Internal Stimuli – from within the organism. – External Stimuli – from outside the organism.
#7: Homeostasis Homeostasis is the process of maintaining internal balance. – Body acidity, oxygen levels, and temperature (even if you’re ectothermic) must all be kept in balance.
Homeostasis Example Humboldt penguins are not cold-weather birds. To deal with warm temperatures in their native South America, the bare skin near their beaks turns red. – The redness is due to increased blood flow to the area, allowing the outside air to cool them.
#8: Evolve Anything that’s considered alive has to have evolved at some point.