1. Chapter 2 Section 1: What is life?
Key Concepts
Cell
What characteristics do all living things share?
Unicellular
Multicellular
Where do living things come from?
Stimulus
Response
What do living things need to survive?
Development
Key Terms (write with enough space to answer them in your ISN):
Spontaneous generation
Autotroph
Heterotroph
Organism
Homeostasis

2. UGGGH That’s so many key tterrrrrrms ugggggggh
I know. Write them down  you do need to know them all.  sorries.

3. Characteristics of Living Things
What do you know about living things? What do living things have in common?
What is the difference between a wind-up toy and a living thing?
All living things have a cellular organization, contain similar chemicals, use energy, respond to their surroundings, grow and develop and reproduce.
Organisms – living things

4. Characteristics of Living things, cont.
Cellular Organization
Chemicals of Life
Energy Use
Response to Surroundings
Growth and Development
Reproduction
(By the end of the section, you should be able to list all of the characteristics of living things as well as explain them.)

5. What is life? Cellular Organization Cell Chemicals of Life Water
Basic unit of structure and function in an organism
Water
Most abundant
Carbohydrates
Unicellular
Energy sources
Single-celled organisms
Proteins and lipids
Includes bacteria
Building materials
Multicellular
Nucleic acids
Composed of many cells
Genetic material

6. What is life? Response to surroundings Reproduction
Growth and Development
Production of offspring similar to the parents
Stimulus (pl. stimuli) – a change that causes an organism to react
Development – process of change to become more complex
This is how new living things are created
Response – an action or change in behavior
NOT spontaneous generation, which is a mistake

7. Redi and Pasteur’s Spontaneous Generation Experiments in brief
Redi’s experiment:
1600s, Italian doctor Francesco Redi
Helped disprove spontaneous generation
Jars with meat
Covered jar drew no flies/maggots
Uncovered had maggots
Redi reasoned flies laid eggs on the meat
Pasteur’s experiment:
Mid 1800s French chemist
Demonstrated that new bacteria appeared in broth only when they were produced by existing bacteria
Clear broth into two flasks; one was boiled to kill bacteria
Unboiled broth became cloudy, indicating bacterial growth

8. Life comes from Life Living things come about from reproduction
Not spontaneous generation – the idea that living things can come from nonliving sources
Redi’s experiment
Summed up: Rotting meat does not produce flies
Pasteur’s experiment
Summed up: New bacteria only appeared in broth when they were produced by existing bacteria
These experiments were important because they showed evidence against spontaneous generation

9. Redi’s Experiment (more in depth)
Italian doctor in the 1600s who designed an experiment to show that flies to not arise from decaying meat.
My wig is the least interesting thing about me.

10. Redi’s experiment Place meat in identical jars
Leave one jar uncovered, cover one jar with a cloth that let in air
After a few days, maggots accumulated in the open jar on the meat
Redi reasoned that flies had laid eggs on the meat in the open jar. Eggs hatched into maggots
Tada.

11. Okay, so, let’s think about Redi’s experiment in terms of what we know about experiments
How do we design an experiment?
Pose questions, hypothesis, collect and interpret data, communicate results.
So, what was Redi’s question?
What was his hypothesis?
What data did he collect? What did he think it meant?
What variables did Redi have? How did he control other variables?

12. Pasteur’s experiment (more in depth)
1800s French chemist
Did some other great germ-theory stuff from which we now have Pasteurization

13. The experiment
Pasteur put clear broth into two flasks with curved necks
Necks let oxygen in but kept out bacteria
Boiled the broth in flask 1, but not the other (flask 2)
Killed bacteria in flask 1
In a few days, the unboiled broth (flask 2) became cloudy (indicating presence of bacteria)
Boiled broth was still clear (flask 1)

14. Pasteur’s experiment
Remember that the necks of the flasks prevented new bacteria from entering.
At this point, we understand that:
1. Boiling the broth in flask 1 killed the bacteria already present, no new bacteria could enter, so the broth remained clear (without bacteria)
2. The unboiled broth had bacteria present, even though no new bacteria could enter, the existing bacteria reproduced and made the broth cloudy
Later, Pasteur took the still-clear broth (flask 1) and broke the neck of the flask. Bacteria from the air could now enter and the broth became cloudy.

15. Pasteur’s experiment, analyzed:
What was Pasteur’s hypothesis?
What were his variables?
What did he have to control to ensure the validity of the experiment?
What does this tell us about the need for controlled experiments?
Write the questions and your answers in your ISNs with a partner

16. The Needs of Living Things
All living things need water, food, space, and stable internal conditions
Stable internal conditions??
Organisms keep homeostasis (maintenance of internal conditions)
What are some examples of homeostasis?
Autotrophs vs. heterotrophs
Autotrophs make their own food (self-feeder)
Heterotrophs eat other organisms

17. What you should know from this section:
Key terms
The 6 characteristics of living things
What livings things need to survive
Don’t forget: water, food, living space, and stable internal conditions.
The experiments were just some background info for you, they won’t be on the test 