The process of sciences - "The way one gets at the truth."

The key steps in the process of science are:

1. Observations

2. Questions

3. Hypotheses

4. Predictions

5. Tests (experiments)

Often the first step in the scientific process is an observation of some phenomena. That observation often leads to a question "Why did it do that"?, Or, "what made that happen"? These questions might suggest an answer or an explanation. That possible explanation is called a hypothesis. This process is often called Inductive Reasoning. That is, specific observations lead to the formulation of general hypotheses.

i.e. Inductive reasoning involves reaching a conclusion based on observations: it moves from the specific to the general.

Newton observed the apple falling therefore he "induced" or drew a general truth "bodies (masses) are attracted towards one another." i.e. Gravity exists

If the hypothesis is a good one, it should allow you to make "predictions". In the example above if the hypothesis that gravity exists is true then we should predict that if we drop a ball it should fall to the ground (earth). Now that you have a prediction you need to "test" the hypothesis to see if the prediction comes true. This process of making predictions based on a hypothesis and then testing them is generally called Deductive Reasoning.

This is a verifying or testing process. It begins with a hypothesis and leads to specific predictions, which can be tested through experiments or observations suggested by the predictions.

Deductive reasoning leads to predictions described as a form of "if . . . then" reasoning.

For example:

Einstein's thinking on relativity led him to the "hypothesis" that light should be bent by gravity.

Therefore one "prediction" of this hypothesis is that a stars’ position in the heavens should change (appear) to change, if another massive star moves between it and the earth.

This prediction required an "observation" to test the hypothesis. This observation was eventually made and the stars’ position does seem to change, therefore the hypothesis is supported but not proved.

 

 

Therefore each time a hypothesis is tested and passes the test it is "strengthened" and the more generally accepted it becomes. Thousands of scientific observations can support a hypothesis but cannot prove it to be true, however one single "repeatable" observation can prove a hypothesis to be false. A theory is an explanation of nature than enjoys considerably more supporting evidence than does a hypothesis.

A theory is defined as "a scientifically acceptable general principle offered to explain phenomena; the analysis of a set of facts in their ideal relations to one another." A good theory relates facts which previously appeared to be unrelated and that could not be explained on common ground. A good theory grows; it relates additional facts as they become known; it may even suggest practical applications. It predicts new facts and suggests new relationships among phenomena. A good theory by showing the relationship among classes of facts, simplifies and clarifies our understanding of natural phenomena. A theory that, over a long period of time has yielded true predictions with unvarying uniformity, and is almost universally accepted, is referred to as a "scientific principle" or "law".

Hypotheses can also be tested by experiment.

An experiment is a contrived situation that tests the hypothesis. Experiments have certain "rules". One rule says that an experiment should begin with a hypothesis.

As well the experiment should be a "controlled experiment".

e.g. from the text book:

You are camping and you go to turn on your flashlight and it doesn’t work. So what is wrong with it?

You will use scientific "hypothetical-deductive reasoning" to decide.

Hypothesis: Maybe the batteries are dead?

Prediction: If we change the batteries with fresh ones the flashlight should work.

Experiment to test that hypothesis: we replace the batteries.

Results: Well if it was the batteries then the flashlight should work.

If it wasn’t the batteries then we need to formulate a new hypothesis and test it.

A good hypothesis allows us to make predictions, the "if …then" statement. "If the batteries are dead, then replacing them will make the flashlight work".

A View of Life (Chapter #1, p. 5-10)

All living things use DNA (or RNA) as the means to store genetic information.

One of the basic observations in biology is that there are fundamental similarities among very different kinds of living things. Such basic similarities implies relatedness therefore a "common ancestry". Even very different forms of life on the planet today may well have "evolved" or descended from a distant common ancestor. This notion is central to the idea of evolution.

Evolution is the gradual change in living things from one generation to the next ("over time").

This change allows some living things to "adapt" to an ever-changing environment.

Life is notoriously difficult to define. It is easier to simply list and describe its characteristics.

a) Life is highly organized.

Nearly everything alive is organized on the "cellular principle". That is organisms are comprised of one or more cells.

Across the spectrum of life, cells have many complex molecules and highly organized and regimented chemical reactions in common. The same key molecules and reactions are present in nearly all life forms.

b) Life requires a constant input of energy and raw materials.

Maintaining a highly ordered state is costly. Much of the material and energy initially entering the living realm is captured by plants and plant-like animals, which use the sun's energy and simple molecules found in the air and water. These organisms "manufacture" their own food using these raw materials and the sun's energy.

They can be thought to "feed themselves" or be self-feeding, i.e. "Autotrophs".

"Heterotrophs" feed on the autotrophs and use their hard-won (stored) food molecules as a source of energy and raw materials for their own purpose.

Therefore energy passes from one life form to the next.

c) Life has a strong homeostatic quality.

"Homeostasis" is the maintenance of a "steady state", a state of chemical and physical consistency in the face of changes in the surroundings. Maintenance of such a steady state requires a sensitivity and appropriate response to even small changes.

d) Life makes many short-term responses to stimuli in the surroundings.

Common stimuli are heat, cold, light, sound, movement, touch, and of course other organisms. The ability to respond to stimuli is essential to all other aspects of life and is fundamental to maintaining Homeostasis. The total pattern of response made by organisms is known as behavior.

e) Life reproduces itself.

Perhaps the most obvious and unique characteristic of life is its overwhelming focus on reproduction. Perpetuation is the key to survival. All of the chemical and physical qualities of life, or those which characterize and define each life form are "replicated" and "preserved" in a new generation of cells and individuals.

 

f) Life adapts through evolution.

The physical, chemical, and behavioral characteristics of life change. Living things constantly adapt to an ever-changing environment. Such adaptations are the products of evolution through natural selection. Evolution is possible only because of myriad variations that exist within each species. Such variations are minute hereditary changes that arise through spontaneous mutation, each to face the test of natural selection. Those changes that pass are preserved, and become the newest adaptations.

Two other characteristics of Life . . .

(Included in some definitions and not in others.)

g) Growth and development.

Biologists restrict the term growth to those processes that increase the amount of living substance in the organism. Growth, therefore, is an increase in cellular mass that is brought about by an increase in the size of the individual cells or by an increase in the number of cells, or, both.

h) Movement.

i) Locomotion - moving of an organism from one place to another (does not occur in all living things).

ii) Movement of living material - e.g. the streaming motion of living material in the cells of the leaves of plants, etc. is known as "cyclosis".

The Organization of Life

There are several "levels" of organization to "life on earth". What follows is a brief introduction to these levels of organization. The remainder of this course will examine each of these levels in much more detail.

I. Chemical level of organization

This is the simplest level of organization. This includes the basic particles of matter, i.e. the "subatomic particles". "Neutrons, protons and electrons". These are combined to form "atoms". An atom is the smallest unit of a chemical element. Atoms combine chemically to form "molecules".

Living organisms have many types of highly specialized "biomolecules", the four largest groups are:

i) Carbohydrates

ii) Lipids

iii) Proteins

iv) Nucleic Acids

II. Cellular level of organization

At the cellular level we find the above biomolecules associated with one another to form complex and highly organized and highly specialized structures within the cell called "organelles". These sub-cellular organelles are each designed to perform specific functions within the cell.

"The cell" itself is the basic structural and functional unit of life. The cell is the smallest and simplest part of living matter that can carry on all the activities necessary for life. Each cell consists of a discrete body of jelly-like cytoplasm surrounded by a cell membrane. The organelles are suspended within the cytoplasm.

Tissues

In most multicellular organisms cells, associate to form tissues, such as muscle tissue or nervous tissue.

Organs

Tissues are arranged into functional structures called organs, such as the heart or stomach.

Organ Systems

Each major group of biological functions is performed by a coordinated group of tissues and organs called an organ system. The "circulatory and digestive system" are examples of organ systems.

III. Ecological levels of organization

The Organism

Functioning together with great precision, the organ systems make up the complex multicellular organism. Organisms interact to form still more complex levels of biological organization.

Populations

All the members of one species that live in the same area make up a population.

 

Community

The population of organisms that inhabit a particular area and interact with one another form a community. Thus a community can be comprised of hundreds of different types of life forms. The study of how organisms of a community relate to one another and with their non-living environment is called "ecology".

A community, together with its non-living environment is referred to as an "ecosystem". An ecosystem can be as small as a pond (or even a puddle) or as vast as the great plains of North American or the Arctic tundra.

The largest ecosystem is the plant Earth with all its inhabitants - "The Biosphere".

 

The Chemical Uniqueness of Life

Living organisms are composed of macromolecules, with the most extraordinary characteristics. For instance, there are nucleic acids that can be translated into polypeptides; enzymes that act as catalysts in metabolic processes, phosphates that permit energy transfer, and lipids that build membranes. Many of these molecules are so specific and so uniquely capable of carrying out one particular function, (e.g. like rhodopsin in the process of photoreception), that they occur in the plant and animal kingdom whenever there is a need for that particular function.

These organic molecules do not differ in principle from other molecules. However they are far more complex than the low molecular weight molecules that are the regular constituents of inanimate nature. These large macromolecules are not normally found in inanimate matter.