Biology and The Scientific Method

What is Biology?Biology is the study of life Biologist study:

How living things workHow living things interact with each

other and the environmentHow living things change over time

The Scientific MethodThe scientific method is

-an organized way of learning about how the natural world works.-a careful, organized series of steps taken to answer questions-a natural/instinctive human process

Answer

Steps of the Scientific Method

There are 6 main steps: Make an observationAsk a question and do research

Form a hypothesis(possible explanation) Design an Experiment

Collect and analyze data Draw Conclusions

ObservationsThe process of science begins with an observation.

ObservationQuestionsExperimentation

Example: I see people using fertilizer on their plants

1. It rained2. The sprinkler was on3. There is dew on the grass

from the morning4. A dog peed on the grass

1. The building is on fire2. The sprinklers

malfunctioned3. The sprinklers are

being tested4. Someone pulled the

fire alarm as a prank

What’s your observation?

What’s your observation?

Possible inferences ?Possible

inferences ?

Asking a Question

At the beginning of every experiment you should state the question you hope to solve by doing your experiment

Example: Does fertilizer cause plants to grow faster?

Forming a HypothesisA hypothesis is an educated explanation of how

an aspect of the natural world worksWhen forming a hypothesis remember:

-It should be based on research (no guessing)-It is one possible answer to your question-It must be testable -It is not always correct and that’s okay-It is posed as a statement of what you think will

happen in your experiment based on what you have already observed

Example: I think that plants grown with fertilizer will grow faster than plants grown without fertilizer because…

Designing an Experiment

Steps to designing an experiment:-Materials- List and gather materials-Procedure- plan and record step by step

instructions for how the experiment will

be performed-Perform the experiment- experiments should be conducted without bias

Designing a controlled experimentIn a controlled experiment two identical or

near identical groups are formed but only one is tested

The Experimental group is directly tested

The control group is not tested so you have a normal standard you can compare results of the experimental group to.

Designing a controlled experimentVariables:

The Manipulated/Independent Variable is what you are testing. It is the one thing you do to the experimental group that you do not do to the control group

Responding/dependent variable is what you observe or measure due to the manipulated variable

Designing a controlled experimentVariables:

What is the manipulated variable in this experiment?

The fertilizer

What would be the responding?The height of the plants

Collecting and Analyzing DataData is collected, recorded, and organized

throughout an experiment by:-Using the senses to make detailed

descriptions and recording in journals-Using tools to take measurements

(size, volume, weight, temperature, etc.) and recording in tables

Data is usually organized into graphs and charts and then analyzed:-to determine whether the results support or fail to support the hypothesis-to determine if results are reliable and possible sources of error-to draw conclusions about the experiment

Drawing Conclusions- After analyzing data you state whether

or not your hypothesis is supported.- An experiment can only disprove, not

prove a hypothesis.- If a hypothesis is incorrect you form and

test a new hypothesis

After the experiment

Sources of errorEquipment errorHuman error

Experiments must be repeatable with similar results to be accepted

Hypothesis vs. TheoryTheory--Common Meaning:

-contemplation or speculation. -guess or conjecture.

Theory--Scientific Meaning:- set of related hypotheses confirmed to be true many times, and can explain a great amount of data

Ex. Cell theory, gravitational theory

Hypothesis vs. Theorycontinued

Similarities Differences

Hypothesis:A proposed scientific explanation based on observations that can be tested.

Theory:An explanation that is supported by reasoning, many observations, many experiments and is highly tested and supported.

The Characteristics of life

1. All living organisms are made up of one or more cells.

I. Cells

All living things reproduce sexually or asexuallyAll cells arise from pre-existing cells by division.

II. Reproduction

All living organisms contain genetic material. Either DNA or RNA. It’s transmitted it during reproductionCarries instructions for building the organism

III. Genetic Material

All living organisms grow and develop.Cell division forms 2 new cells from an existing cellDevelopment=cell division,cell differentiation/specialization

IV. Growth and Development

All living organisms use energy 1.Energy flow (metabolism and biochemistry) occurs

within cells.

V. Energy

All living organisms respond to their environment

VI. Response

All living organisms maintain a stable internal balance even though the environment (temperature, pH) is constantly changing

VII. Homeostasis

Living organisms change over time

VIII. Evolution

All living organisms die

IX. Death