Bio Warm Up #21. Explain what a hypothesis is and provide an

example. 2. Charles does an experiment and finds that

Plant A grew faster than plant B. This is a,a. Result b. theory c. hypothesis d. procedure3. List the 6 major steps of the scientific method.4. The ________ (manipulated/responding)

variable is the variable that is changed during an experiment.

Chapter 1.1 & 1.2

The Science of Biology

Question:

What is biology?

Thinking Like a Scientist

• Scientists ask QUESTIONS• Make OBSERVATIONS• Observations turn into DATAQuantitative Data

Data based on NUMBERSQualitative Data

Data based on OBSERVATIONS

How Scientists Work

What do scientists do?Why should we care?

Designing Experiments

• Start with a QUESTION• OBSERVE• Form a HYPOTHESIS testable, in “if/then” form• Design EXPERIMENT• Record & analyze RESULTS• CONCLUDE

Hypothesis

• Question based on prior knowledge • Testable • Accept or reject Ex: “If I water my plants for five days, then my

plants will grow by 5 cm because I watered them everyday.”

PRACTICEWrite a hypothesis for the following

scenarios. Remember, use “if… then”, format!

1.Air conditioner breaks down in your house

2.Your friend gets sick after eating a chicken sandwich

3.Your dad’s car doesn’t start in the morning

Controlled Experiments

• When one variable is changed at a time• You CONTROL certain things about the

experiment.

Ex: You do an experiment where you want to test two different fertilizers on strawberry plants. Must control: amount of water you give them, how much light they both get, make sure it’s the same type of plant, etc. You only change what type of fertilizer you give the plants.

Controlled Experiments

Two types of variables:1.Manipulated variable = variable that is

CHANGED2.Responding variable = variable that is

OBSERVED

PRACTICE Find the manipulated and responding variables in

this experiment and explain what you should CONTROL:

Franky finds that flies appear in the kitchen when he leaves steak uncovered, out on the counter. He is unsure why this happens, so he designs an experiment. He leaves out two pieces of steak. One piece is uncovered, while the other piece is covered with plastic wrap. He waits two days. The steak that is uncovered appears to have flies on it.

PRACTICEMichelle threw away a garbage bag that had

food in it. Two days later she came back and found maggots in the trashcan. She designed an experiment to test what happened. She left one trashcan inside and another one outside. She placed the same type of trash in both cans. She waited two days. She found the trashcan that was outside had maggots while the one inside did not.

Theory vs. Hypothesis

Theory = well tested explanation; unifies a range of observations

Not absolute truthEx: Theory of relativity, theory of evolution,

theory of plate tectonics

Hypothesis = an educated, testable question

Inconsistent Results

• Happens when you have sources of ERROR:Incorrect measurementsToo many variablesNo controls

Q: What are other possible types of errors?

Scientific Evidence

Science BUILDS upon itselfAlways changingEvidence builds up, new theories are created