The Study of Life Chapter 1

Biology Bios – life Logos – to reason, the study of

Why study biology?

How do scientists study the world around them?

Scientific Process No one “cookbook” method for conducting science

Scientific Method 1 - Observe Example - Notice that many trees lose their leaves in the fall at about the same time it starts getting colder.

Scientific Method 1 – Observe 2 - Hypothesize Notice that many trees lose their leaves in the fall. Trees lose leaves because it is colder

Hypothesis an educated guess; our best explanation for why or how something happens; must be testable

Theory An explanation that has been repeatedly tested and always found to be true. Often a theory is an explanation that draws on several different hypotheses.

Law or Principle A fact; an absolute; an explanation that is beyond questioning. Not many laws in biology. Is evolution a scientific theory or a principle?

Scientific Method 1 - Observe 2 - Hypothesize 3 - Experiment Notice that many trees lose their leaves in the fall. Trees lose leaves because it is colder. Place identical trees in different environments.

Variables Factors which can change and may affect the experiment Examples? Temperature, Water, Fertilization, Light, etc.

Variables Independent: the tested factor that might change the outcome of an experiment (the treatment) Dependent: the factor being measured Usually only one variable at a time is allowed to change. Why only one?

Controls A group used for comparison

Constants A factor that remains fixed during an experiment while the independent and dependent variables change

Scientific Method 1 - Observe 2 - Hypothesize 3 - Experiment 4 - Objective evaluation Compare trees’ responses Publish results

Scientific Method 1 - Observe 2 - Hypothesize 3 - Experiment 4 – Objective Evaluation 5 - Decision and Repeat Try a new test of hypothesis

What is life?

Life resists a simple, one-sentence definition, yet we can recognize life by what living things do.

What is life? The quality that distinguishes a vital and functional being from a dead body. The period of time from birth to death. An organismic state characterized by the capacity for metabolism, growth, reaction to stimuli, reproduction, etc.

… There are 8 unifying themes in the Science of Biology These 8 themes are the characteristics of life.

1. Cell structure and function All living things are composed of one or more cells. A cell is the smallest unit of life Organisms may be unicellular or multicellular

2. Displays organization From the chemical level to the entire organism, all organisms displays organization. What are the levels of organizations of living things?

3. Growth and development Growth results in the increase in mass. Development results in different abilities.

4. Reproduction All living things can reproduce Reproduction is the process by which organisms make more of their own kind from one generation to the next by passing along their traits.

5. Responds to stimuli Reactions to internal and external stimuli are called responses. Interdependence--All organisms in a biological community interact with one another. Organisms are dependent on one another and their environment.

6. Requires energy Metabolism - all the chemical changes within a living organism. - all of the processes used by an organism to acquire, transform and use energy.

7. Homeostasis Homeostasis – maintenance of stable, internal conditions necessary to sustain life; e.g. temperature, pH, O 2 levels, blood pressure, etc.

8. Evolution All life on earth has adapted to their surroundings and evolved (changed) over a long period of time.

How can you incorporate these themes into your life? Would you be considered alive without one of these characteristics? What are some biology related problems in this world?