The Science of Biology

The Scientific “Method”

Chapter 1 Outline

1-1: What is Science? What Science Is and Is Not Thinking Like a Scientist Explaining and Interpreting Evidence Science as a Way of Knowing Science and Human Values

1-2: How Scientists Work Designing an Experiment Publishing and Repeating Investigations When Experiments are Not Possible How a Theory Develops

Chapter 1 Outline

1-3: Studying Life Characteristics of Living Things Branches of Biology Biology in Everyday Life

1-4: Tools and Procedures A Common Measurement System Analyzing Biological Data Microscopes Laboratory Techniques Working Safely in Biology

What Science Is and Is Not

In the Science Classroom, the objective is to take problems and approach them scientifically. The Goal of Science is to investigate and understand the

natural world, to explain events in the natural world, and to use those explanations to make useful predictions.

The three features that makes science a unique human endeavor: Science deals only with the natural world Scientist collect and organize information looking

carefully for patterns and connections between events Scientists propose explanations that can be tested.

What Science Is and Is Not

Science is an organized way of using evidence to learn about the natural world.

Science is also the study of nature in an attempt to understand it and to form an organized body of knowledge that has predictive power and application in society.

Thinking like a Scientist

Thinking like a scientist involve looking at a problem and gathering information to help solve the problem.

Scientific thinking usually starts with observations. The process of gathering information about

events or processes in a careful, orderly way. The observations are usually collected

through the five senses and is called data.

Thinking Like a Scientist

There are two main Categories of Data Quantitative Data

Data expresses as numbers, obtained by counting or measuring

Examples: Amounts, Weights, Numbers, etc.

Qualitative Data Data that is descriptive and involve characteristics

that cannot be counted. Examples: Color, Feelings, etc.

Thinking like a Scientist

Once scientists have collected enough data, an inference can be made. Inference – a logical interpretation based on

prior knowledge or experience.

Explaining and Interpreting Evidence

After enough data has been collected and inferences made, scientist can now propose one or more hypotheses. Hypothesis – a proposed scientific explanation

for a set of observations. A hypothesis must also have the ability to be

tested. Some hypothesis are tested by:

A Controlled Experiment Gathering more Data

Explaining and Interpreting Evidence

Scientists do not work alone Many Scientists can come together to

collaborate in teams to work on complex questions.

They do this in order to validate conclusions and come to a general consensus on a hypothesis.

Science as a Way of Knowing

Science is an ongoing process that involves asking questions, observing, making inferences, and testing hypothesis to explain a natural phenomena.

Scientific understanding is always changing. As technology and research techniques get more sophisticated, scientific theories and principles can evolve. Example: Human Genome Project

Science as a Way of Knowing

What Science cannot do? Science cannot tell you what to believe

It cannot help you decide what is beautiful It cannot decide what is good or evil

Science is used to explain NATURAL phenomena

It cannot be used to explain the supernatural Example: Galileo and Heliocentrism

Science and Human Values

Along with scientific facts and concepts, the application of science is technology.

As science progresses, humans use technology to create a better standard of life.

Examples of how science has improved life: Sanitation Health Care Agriculture and Farming

Science and Human Values

Science and Technology can also cause heated debates: Genetics Stem Cell Research Cloning

Designing and Experiment

To Model How Scientist Work, we will discuss an early experiment, which tested the hypothesis of spontaneous generation. Spontaneous Generation – The hypothesis that

states life can arise from nonlife. The Observation:

Some organisms seem “to be born” from nonliving things

Maggots from meat Mice from Grain Beetles from Cow Dung

Designing an Experiment

Forming a Hypothesis In 1668, Francesco Redi, an Italian Physician,

proposed a hypothesis against Spontaneous Generation

He proposed that it was not the meat that was producing the maggots, but the flies that landed on the meat that produced the maggots.

In order to test his hypothesis, he set up a controlled experiment.

Designing an Experiment

Setting up a Controlled Experiment A controlled experiment is used to test

hypotheses. In experiments, there are factors that can be

changed called variables Examples: Equipment Used, type of material, amount

of material, temperature, light, and time. Whenever possible, a hypothesis should be

tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged or controlled.

Designing an Experiment

A controlled experiment contains: A Manipulated Variable

The variable that is deliberately changed

A Responding Variable The variable that is observed and that changes in

response to the manipulated variable

Redi’s Controlled Experiment

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.

PROCEDURE

Controlled Variables:jars, type of meat,location, temperature,time

Manipulated Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appear

Responding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Designing an Experiment

Recording and Analyzing Results In a controlled experiment, data, specifically

quantitative data, is important. Drawing a Conclusion

After all the data has been accumulated and analyze, a conclusion can be made about the experiment.

It can either support or refute a hypothesis.

Publishing and Repeating Investigations

Just because an experiment yielded the desired results one time does not mean it will produce the same result a second time. Therefore, after scientists publish their results, other scientists tests the findings to verify the results.

Redi’s Experiment were tested by Needham, Spallanzani, and Louis Pasteur.

Spallanzani’s Experiment

Gravy is boiled. Flask isopen.

Gravy is teeming with microorganisms.

Gravy is boiled. Flask issealed.

Gravy is free of microorganisms.

Louis Pasteur’s Experiment

In 1864, Louis Pasteur decided that he wanted to end the argument on spontaneous generation.

He developed a special flask in which he boiled nutrient broth, thus killing any microorganism. Since the flask had a special neck that did not allow the broth to be exposed to dust in the air, no microorganisms grew. A year later, he broke the neck, and within an evening, the broth was teeming with microorganisms.

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

How a Theory Develops

A Particular hypothesis may become so well supported that scientists consider it a theory In science, the word theory applies to a well-

tested explanation that unifies a broad range of observations

Theory help explain a natural phenomena. Examples: Evolution, Plate Tectonics and the

Kangaroo. Theories are not absolute, they can be

changed.

Characteristics of Living Things

Biology is the study of life. Biology is the science that seeks to understand the living

world. Living things share the following characteristics:

Living things are cellular Living things reproduce Living things are based on a universal genetic code Living things Grow and Develop Living things obtain and use materials and energy. Living things respond to their environment Living things maintain a stable internal environment Taken as a group, living things change over time.

Characteristics of Living Things

Made Up of Cells A cell is a collection of living matter enclosed by

a barrier that separates the cell from its surroundings.

Unicellular = One Celled Organism Multicellular = Many Celled Organism Learn more in Chapter 7

Characteristics of Living Things

Reproduction All organism produce new organisms through

the process of reproduction Two types:

Asexual Reproduction Single Parent Clones Bacteria and most protists

Sexual Reproduction Two Parents New organisms is a combination of the parents. More Complex Organisms (Animals and Plants)

Asexual Reproduction

Characteristics of Living Things

Based on a Genetic Code All Living things inherit traits from their parents. DNA is the genetic material used to pass on

traits. Growth and Development

All living things grow during their lifetime Unicellular Organisms grow in size Multicellular Organisms multiply and develop.

Some organisms have a very complex development

Characteristics of Living Things

Need for Materials and Energy A living organism must be able to obtain energy

from the environment. Some organisms create their own food while

others obtain them from other sources. Either way, an organism must be able to metabolize that food into cellular energy.

Metabolism – the combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes.

Characteristics of Living Things

Response to the Environment Organisms detect and respond to stimuli from

the environment Stimulus – a signal to which an organism responds.

Two types: External Stimuli Internal Stimuli

Characteristics of Living Things

Maintaining Internal Balance In order to survive, organisms must be able to

keep their internal environment normal. Homeostasis – the process by which organisms

maintain their internal environment. Usually through the use of two feedback mechanisms

Positive Feedback Mechanisms Giving Birth

Negative Feedback Mechanisms Temperature Control

Branches of Biology

Some of the levels at which life can be studied include molecules, cells, organisms, populations of a single kind of organism, communities of different organisms in an area, and the biosphere. At all these levels, smaller living systems are found within larger systems.

Biosphere

Ecosystem

Community

Population

The part of Earththat contains allecosystems

Community and its nonliving surroundings

Populations thatlive together in a defined area

Group of organisms of onetype that live in the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

Section 1-3

Figure 1-21 Levels of Organization

Organism

Groups ofCells

Cells

Molecules

Individual livingthing

Tissues, organs,and organ systems

Smallest functionalunit of life

Groups of atoms;smallest unit of most chemicalcompounds

Bison

Nervous tissue Nervous systemBrain

Nerve cell

Water DNA

Section 1-3

Figure 1-21 Levels of Organization continued