Chapter OneThe Science of Biology

Biology = the study of life

1-1 What is Science?

What is Science?Science is an organized way of using evidence

to learn about the natural world.

What is the goal of science?

To investigate and understand nature, to explain events in nature, and to use those explanations to make useful predictions.

In other words the goal of science is

1) to deal only with the natural world

2) to collect and organize information

3) to propose explanations that can be tested

Science begins with observations

data - the information gathered from observationsquantitative data = numbersqualitative data = descriptive

inference - a logical interpretation based on prior knowledge or experience

hypothesis - a proposed scientific explanation

1-2 How Scientists Work (page 8)

Spontaneous generation - the idea that life could arise from non-living matterExample: maggots arise from meat

The Scientific Process

involves making observations and asking questions about what we observe in nature.

Method of the Scientific Process:

Problem = question (why is something the way it is?) or: Purpose of research

Research: find out as much as possible about the question – this will allow you to make a prediction

Create a hypothesis: provide a “researched” explanation of the problem

Conduct an experiment (a planned procedure to test your hypothesis)

Analyze the results of your experiment Conclusion: accept or reject the hypothesis

(use Ch.1 Notes)

Let’s go through the steps: Imagine you are a scientist and you notice that

there are fewer frogs in the pond near your house than in the pond near your parents’ house

1.Problem/Observation: Fewer frogs (purpose: want to find the

reason there are fewer frogs in my pond)

Imagine you are a scientist and you notice that there are fewer frogs in the pond near your house

than in the pond near your parents’ house

2. Research: Has someone else researched this

problem?

Go online, talk to other scientists, read scientific journals

Imagine you are a scientist and you notice that there are fewer frogs in the pond near your house

than in the pond near your parents’ house

3. Hypothesis:

There is a substance in this one pond that is reducing the number of frogs.

Imagine you are a scientist and you notice that there are fewer frogs in the pond near your house

than in the pond near your parents’ house

4. Experiment: I test the water in my pond and in 4 other

ponds to find out if any chemicals are only in my pond

Imagine you are a scientist and you notice that there are fewer frogs in the pond near your house

than in the pond near your parents’ house

5. Analyze results: Look at the test results and compare

chemicals of all the different ponds to see if any chemicals are only present in my pond

Imagine you are a scientist and you notice that there are fewer frogs in the pond near your house

than in the pond near your parents’ house

6. Conclusion:

There is one chemical in my pond that is not present in other ponds. This chemical might interfere with frog reproduction.

Most researchers also include this: Suggestions for future research:

Test the chemical on frogs to find out exactly how it harms frogs

Another example: Apply the steps of the scientific process

Step 1: Observation

You observed that your skin became more orange after drinking a lot of carrot juice. You want to find out if that just happened to you or if it will also happen to other people.

Apply the steps of the scientific process.

Step 2: Research

Step 2: ResearchInformal research: ask other people, ask a

physician, “Google” it

Formal research: read scientific journals

Step 3: Hypothesis

Step 3: HypothesisSkin turns more orange after drinking a lot of

carrot juice.

Step 4: Experiment

Step 4: Experiment

Pre-experiment:

find a large group of subjects

take a photo of each

divide subjects into 2 groups

Experiment:

give each subject in one group 24oz of carrot juice, three days in a row. The subjects in the other group do not drink any carrot juice.

Step 5: Analysis

Step 5: Analysis Take photographs of every one’s skin again.

Compare before and after photos. Analyze the results to determine whether or not the carrot juice discolored skin.

Step 6: Conclusion

Step 6: Conclusion State whether or not the carrot juice changed

skin color

The 4th step (perform experiment) in detail:

You must have at least 2 groups to compare, for example one that drinks carrot juice and one that does not).

The group that receives the treatment (drinks the carrot juice) is called the experimental group

The group that is used for comparison (does not receive the treatment = does not drink carrot juice) is called the control group.

The control and experimental group(s) are designed to be the same except for one factor, or variable (the carrot juice)

The 4th step (perform experiment) in detail, cont.:

The one variable, or factor, that is different between the groups (the carrot juice) is called the independent variable

What is measured at the end of the experiment (skin color )is called the dependent variable.

Examples:I want to know if an SAT test preparation

class improves SAT scores.

How would I set up the experiment?

Examples:I want to know if an SAT test preparation

class improves SAT scores.

How would I set up the experiment?I could find a large number of students and

divide them into two groups. I would try to keep the groups the same in terms of education, school grades, age and socioeconomic background and I would instruct them to not study any other materials for the SAT.

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What would my hypothesis be?

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What would my hypothesis be?

Taking this SAT test preparation class will improve SAT test scores.

Examples:I want to know if an SAT test preparation

class improves SAT scores.

Which would be the Experimental group?

Examples:I want to know if an SAT test preparation

class improves SAT scores.

Which would be the Experimental group?The group that takes the test preparation class (receives the

treatment).

Examples:I want to know if an SAT test preparation

class improves SAT scores.

Which would be the Control group?

Examples:I want to know if an SAT test preparation

class improves SAT scores.

Which would be the Control group?

The group that does not take the SAT preparation class (does not receive the treatment).

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What would be the independent variable?

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What would be the independent variable?

The test preparation class.

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What would be the dependent variable?

.

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What would be the dependent variable?

= what I measure at the end of the experiment

= SAT test scores

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What am I comparing?

Examples:I want to know if an SAT test preparation

class improves SAT scores.

What am I comparing?

The performance between the group that took the SAT preparation class and the group that did not take it.

Examples:I want to know if an SAT test preparation

class improves SAT scores.

At the end of the experiment, after I have analyzed my data, I confirm or reject my hypothesis.

If the class made a difference in test scores, then I would have confirmed my hypothesis.

Practice:I want to know if a new hair care product will

make hair grow faster than a regular shampoo.

How will you set up an experiment?

What are you comparing?

What is the hypothesis?

What is the experimental group? What is the control group?

What is the independent and dependent variable?

How would you confirm or reject your hypothesis?

Now practice on your own:“Homer Simpson” Scientific Method Practice:

Get into groups of 2 people.

Use one paper for both people.

Write the name, date, and activity title on your paper.

Write down the answers for all 6 examples.

Make sure you use a heading for each example, e.g. Bart and his mice.

Theory vs. HypothesisTheory: a well-tested explanation that unifies a

broad range of observations. NOT ABSOLUTE

Hypothesis: a possible explanation for a set of observations

Gravity is a theory!!

When experiments are not possible

Field studies = observational studies

Example: effect of smoking during pregnancy on birth

weightDoes a certain chemical cause cancer (can be an

experimental study with animals such as mice, but is not allowed with humans)

1-3 Studying Life (page 16)

biology means the study of life

Bios = life -logy = study of

Characteristics of All Living Things:

1. Are made of one or more cells

2. Reproduce

3. Carry out chemical reactions to maintain metabolism

4. Try to keep a stable (balanced) internal environment = homeostastis

5. Pass on characteristics to their offspring (children) = heredity

6. Change over time = evolution

7. Respond to the environment = adaptation

8. Grow and develop

Are these alive?

Plants, rocks, water, roaches

Can you think of something that many people think is alive but is not?

Levels of organization (page 21, figure 1-21)

1-4 Tools and ProceduresScientists use a common measurement system: the

metric system

Metric system - decimal system of measurements, units are scaled on multiples of 10

UNIT – MEASURING TOOL

Length: Meter, Centimeter, Kilometer – Ruler, Meter Stick

Volume: Liter, Milliliter – graduated cylinder

Mass: Kilogram, Gram – scale, balance

Analyzing dataTables, Graphs, Charts, Drawings, Models, etc

Microscopes -Produce a magnified image of structures

Light Microscope May be Simple or Compound (one lens) or (two or more lenses) **Specimen can remain alive**

Electron Microscope SEM (Scanning Electron M.) - 3-D image TEM (Transmission Electron M.) - through an image

**Specimens cannot be observed while alive** (see regular bio book)

Laboratory Techniques Cell culture - group of

cells grown in a nutrient solution from a single original cell

Cell fractionation - technique in which cells are broken into pieces and parts are separated