Introduction: Themes in the study of life Lec # 1 Instructor: Dr. Hatem Eideh Course: General Biology Reference: Reece JB, Urry LA, Cain ML, Wasserman SA, Minorsky PV and Jackson RB (2011). Campell Biology, 9 th ed. Boston: Pearson Education.. Chap 1

Characteristics of living things What is life? What is biology? What are the characteristics of living things?

Levels of biological organization

Scientific methods

What the scientist is doing?

Scientists use two main forms of Inquiry in their study of nature What is “science”? At the heart of science is “Inquiry”, the search for information and explanation, often focusing on specific questions. Scientists attempt to understand how natural phenomena work by using a process of inquiry that includes Making observations Forming and testing hypotheses

Making observations Describes natural structure as accurately as possible through careful observation and analysis of data Example: cell structure Types of data ◦ Qualitative > recorded descriptions ◦ Quantitative > measurements Inductive Reasoning: derive generalizations from a large number of specific observations Example: “ the sun always rises in the east”; “all animals are made of cells”

Forming and testing Hypotheses Observations and Inductive Reasoning stimulate us to seek natural causes and explanations for those observations Example: what causes the plant leaf-bearing shoot to grow upward? The role of hypothesis in the inquiry?? A hypothesis is a tentative answer to a well-framed question- an explanation on trial. Example: your flashlight fails during a camp-out?

A campground example of a hypothesis-based inquiry.

Deductive Reasoning and Hypothesis Testing Deduction: the “If… Then” logic of hypothesis-based science Deduction contrasts with induction Deductions: It is generally used after the hypothesis has been developed, the logic flows in the opposite direction, from general to the specific Example: if the dead battery hypothesis is correct, and you replace it with new ones, then the flashlight should work. Example: if all organisms are made of cells, and humans are organisms, then humans are composed of cells. A hypothesis must be : testable & falsifiable

The flexibility of scientific method Very few scientific inquiries adhere rigidly to the sequence of steps prescribed by the “textbook” scientific method. You may start designing an experiment, then realizes that more observations are needed.

Experimental Controls and Repeatability An experiment must be designed to demonstrate the effect of ONE variable by testing control groups and experimental groups that differ in only ONE variable Example: compare the cholesterol levels in atherosclerosis' patients with healthy persons, of same age and sex What is the purpose of using a control group?

Experimental Controls and Repeatability A hallmark of science is that experimental results and observations must be repeatable Observations that cannot be verified are interesting but cannot account as evidence in scientific inquiry

Field experiments with artificial snakes

Theories in science A scientific theory is much broader in scope than hypothesis Hypothesis: Mimicking the coloration of venomous snakes is an adaptation that protects non- venomous snakes from predators Theory: evolutionary adaptations arise from natural selection

Theories in science A theory is general enough to spin off many new,, specific hypothesis that can be tested Compared to any one hypothesis, a theory is generally supported by a much greater body of evidence If there is “truth” in science, it is conditional, based on the preponderance of available evidence

Science benefits from a cooperative approach and diverse viewpoints Building on the work of others Cooperation is facilitated when scientists use same model organism Science, technology and society The value of diverse viewpoints in science