What does it mean to be LIVING?

Life Requires Organization

Studying biology is impossible without organization. Throughout this course, information will be broken down into categories based on:

•Similarities and differences

•Increasing or decreasing complexity

•size

By looking at the various levels of organization in our environment we can begin to see how the different parts work together.

The Parts vs. The Whole

We can neither understand only the parts nor only the whole of the system; we must understand both.

We cannot understand how a bicycle works by looking at the parts in a box and we can also not truly understand that bicycle without taking it apart and looking at the pieces.

Emergent properties – novel properties that appear as the level of complexity of a system increases.

A test tube filled with enzymes, chloroplasts, and CO2 cannot perform photosynthesis. It is the parts functioning as a system that allow this life giving process to occur. Photosynthesis is an emergent property.

None of the parts alone may appear to be very complex, nor can their jobs be determined. It is not until we observe the whole, with each part working, that we discover the emergent properties.

The PARTS

Reductionism – reducing complex systems to simpler components that are more manageable to study.

Take a cell: There are organelles, ions, DNA enzymes, water, and other materials. These are the parts.

The WHOLE

Systems Biology – models that dynamic behavior of whole biological systems.

Accurate models in systems biology help us to see what will happen to the system if one of the parts is no longer functioning or is removed.

A B C+

Negative feedback is the way that most living processes are controlled.

The accumulation of end-product D interferes with the chemical process that created D.

In order to understand the system, scientists have had to find and study all the parts. In order to understand the parts, however, scientists have had to study them in the system.

Parts } System

Positive feedback is another example of regulation as well as a system and its parts

Here the creation of end-product Z increases its own production.

Parts } System

Taxonomy – the branch of biology that names and classifies species and organizes those species into a series of groups with increasing breadth.

This is done by looking at the similarities and differences between the organism to be classified and the rest of the known system.

Organism }(System)(Part) Taxonomy

Evolution – the birth of similarities and differences. Evolution means a change over time.

Notice the very similar nature of the cilia….

… in very different organisms.

Charles Darwin explained in his book, On the Origin of Species by Natural Selection, that:

•Modern species arose from a succession of ancestral ones (decent with modification.)

•These modifications arose because of selection pressure from the environment – natural selection.

These variations (difference) on a common theme (sameness) are what scientists study when looking at unity and diversity.

Using a tree diagram is not only a great way to look at Darwin’s theory, but also a great way to arrange other diverging and converging information in Biology.

THE Scientific Method?

This is the typical format taught to all science students about the scientific method.

Role of the HypothesisA hypothesis is a testable, tentative answer to a well framed question.

It is convenient to formulate the hypothesis as an “If…then…” statement.

If I replace the batteries in the flashlight, then the flashlight will work.

A well formulate hypothesis must also be falsifiable…

Flashlight + Batteries =

The experiment designed to test the hypothesis should be a controlled experiment.

The experimental design does not control all the factors in the environment, but rather cancels out the effect of unwanted variables by having a well crafted control with which to compare the results in the experimental groups.

Ideally, the experimental groups (being tested) differ from the control group (basis of comparison) by only one factor

A case study in scientific inquiry: Investigating Mimicry in Snake Populations

Many poisonous animals ‘advertise’ that they are dangerous with bright coloration.

This prevents their being eaten by predators. This is evolutionarily advantageous

British scientist, Henry Bates postulated that some animals have evolved to mimic these colorations. It is believed that this mimicking confuses predators and prevents the non-poisonous species from being eaten as well. Another beneficial adaptation.

Poisonous

Non-poisonous

Which one would you eat?

The Harcombe-Pfennig Experiment

Both the coral snake (poisonous) and the king snake (non-poisonous) live in the Carolinas. The range of the king snake and the coral snake overlap, but are not identical. The king snake mimics the coloration of the coral snake

This factor is key for the study since the hypothesis is that mimicry should only confer protection from predators in an area where the actual poisonous species also lives.

"Red on yellow, kill a fellow. Red on black, won't hurt Jack."

Procedure:

1. Two versions of fake snakes were created. The ones representing the king snakes were the experimental and the plain brown were the control.

2. Equal numbers of both types were placed in the overlapping habitats as well as in the areas were coral snakes were absent.

3. After 4 weeks the fake snakes were retrieved and the number of attacks on each were recorded.

Results:

In field sites were coral snakes were present, predators attacked fewer artificial king snakes then brown snakes.

The coloration provided no protection in areas were coral snakes were absent.

In fact, in areas with coral snakes absent, the attacks on the artificial king snakes were higher then that of the false brown snakes.

This is probably because they were much easier to see.

Conclusion:

This experiment supported the hypothesis that imitation of coral snakes is only effective where coral snakes are present.

It also falsified an additional hypothesis that was made before experimentation that predators generally avoid all brightly colored snakes whether or not poisonous snakes with that coloration live in the environment.

1) Which of the following properties or processes do we associate with living things? A) evolutionary adaptations B) energy processing C) responding to the environment D) growth and reproduction E) all of the above

2) Which of the following sequences represents the hierarchy of biological organization from the least to the most complex level? A) organelle, tissue, biosphere, ecosystem, population, organism B) cell, community, population, organ system, molecule, organelle C) organism, community, biosphere, molecule, tissue, organ D) ecosystem, cell, population, tissue, organism, organ system E) molecule, cell, organ system, population, ecosystem, biosphere

3) In order to understand the chemical basis of inheritance, one must understand the molecular structure of DNA. This is an example of the application of ________ to the study of biology. A) evolution B) emergent properties C) reductionism D) the cell theory E) feedback regulation

E

E

C

4) What is a hypothesis? A) the same thing as an unproven theory B) a tentative explanation that can be tested and is falsifiable C) a verifiable observation sensed directly, or sensed indirectly with the aid of scientific instrumentation D) a fact based on qualitative data that is testable E) a fact based on quantitative data that is falsifiable B5) What is the primary reason for including a control group within the design of an experiment? A) To ensure that the results obtained are due to a difference in only one variable B) To ensure that the experimenter can perform a more complete statistical analysis C) To demonstrate in what way the experiment was performed incorrectly D) To accumulate additional facts that can be reported to other scientists E) To test the effect of more than one variable

A