Scientific Thinking and Processes Section 1-3

What is Science? Science- organized way of thinking and using evidence to learn about the natural world

Goal of Science Goal- investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions Only deals with natural world

Goal of Science Collect and organize information in a careful, orderly way looking for patterns –EX: fertilizer treatment –Amount? –Brand? –Time? –Change in Growth?

Thinking like a Scientist Observation- the process of gathering information about events or processes in a careful, orderly way Uses all five senses –When appropriate –If safe

Information from Observation Data- information gathered from observations 2 categories of data –Quantitave data- numbers, counts, measurements EX: 5 cm tall, 4 people died, 71 grams –Qualitative data- descriptive EX: brown-green mold, cottony texture –USE BOTH!

Inferences Data can lead to making inferences Inference- logical interpretation based on prior knowledge –May or may not be correct

The Hypothesis Observations can also help with hypotheses Hypothesis- proposed scientific explanation for a set of observations –Have to be able to be tested

Valid Hypothesis? More people prefer Coke over Pepsi. Everyone prefers Coke over Pepsi. Women will be less aggressive than men. Women will have less aggressive verbal interactions at work than men.

Valid Hypothesis? Enthusiastic teachers are better teachers. Plants exposed to 6 hours of direct sunlight will grow taller than plants exposed to no sunlight. People who don’t forward chain s have worse luck than those who don’t.

Science as a way of Knowing Ongoing process Must re-evaluate **ONLY FACT, NOT OPINION** Universe is a whole system –Biology—focuses on system of living thing

Science and Human Values

Science permeates into everything we do Decisions are not solely based on science Society Harmony or clash can exist

How Scientists Work Section 1-2

Recipe for Bees 1.Kill a bull during the first thaw of winter. 2.Build a shed. 3.Place the dead bull on branches and herbs inside the shed. 4.Wait for summer. The decaying body of the bull will produce bees.

Setting up a Controlled Experiment Controlled experiment- experiment where only one variable is changed at a time Two types of variables –Manipulating variable- variable that you deliberately change EX: covering or not covering jar –Responding variable- variable that changes in response to the manipulated variable EX: presence of flies

Drawing a Conclusion Hypothesis doesn’t always have to be correct Data, statistics, and logic work together Does it make sense?

Spontaneous Generation Life arises from non-living matter or just suddenly appear. Meat grows maggots Corn produces rats Bread breeds mold So what do you think of this theory?

How can we prove or disprove this hypothesis? 1.Francesco Redi (1668) Hypothesis: Flies produce maggots on meat. Lay small eggs Set up a controlled experiment to test his hypothesis Found that by keeping flies away from meat, no maggots appear

Variables 1.Controlled variable: Jar, meat, location, temperature, time 2.Independent or Manipulative variable: Gauze covering the meat jars 3.Dependant (responding) variable: Whether maggots appear

John Needham – 1745 Hypothesized that spontaneous generation occurs under the right conditions – Boiled chicken broth and then sealed flask (thought heat would kill) – “Animalcules” swarmed after a few days – Therefore, he felt his hypothesis was right.

What was wrong with Needham’s hypothesis? Was it flawed? He assumed all the animalcules would be killed by heat

Lazzaro Spallanzani 1776 Attempted to disprove Needham’s work. Took 4 flasks with broth in them – Left open – went cloudy – Sealed but not boiled – went cloudy – Boiled but left open – went cloudy – Sealed then boiled – stayed clear Microbes were not found in this one but in all the other ones

What would have been Spallanzani’s hypothesis? Microorganisms form not from air but from other microorganisms. When broth was boiled and then sealed, no air could get in for organisms to reproduce.

What was wrong with what Spallanzani assumed? No air

Louis Pasteur Tested Spallanzani’s work by using a curved neck flask to prevent microbes from entering flask but would let air in Boiled broth of control and experimental flasks. Result: No growth in curved neck flask. Microbes collecting in bend

Pasteur’s broth in the curved necked flask stayed sterile for years until he tilted it and the airflow carried the microbes into the broth

Conclusion Contamination is due to microbes in the air. Spontaneous generation theory died here!! Biogenesis is born!! All living things come from other living things.

What if an experiment isn’t possible? EX: Animal behavior Other options: –Field studies EX: Ethical concerns –Animal testing (as opposed to humans) –Case studies –Reviewing data secondhand

Tools and Procedures Section 1-4

Common Measurement System The metric system – Metric system- system of measurements whose units are based on standards and are scaled on multiples of 10 SI Units –Revised metric system

Metric review

Micoscopes Microscope- device that produces a magnified image of structures that are too small to be seen with the unaided eye Many types

Microscopes Light microscopes –Focus beams of light –Up to 1000x magnification –Can see living and dead organisms –Can use stains to see detail

Microscopes Electron microscopes –Focus beams of electrons –Up to 1x 10 6 x magnification –Cannot have living specimens; must be dried and preserved

Cell Culturing Takes a single cell of interest in a nutrient solution and grows it From that single cell a whole group (a culture) would arise and be genetically the same –Can then test for responses, interactions, and select for certain traits

Cell Fractionation Separating out different parts of the cell 2 main steps –Break up the cells so the parts can be separated –Separate the cells with a centrifuge