Chapter 1 Study of Life

1.1 Science of Biology

What is the Nature of Science? Scientific method used to answer questions about nature Observation Question Hypothesis – “educated guess” Prediction - testable statement Experiment Conclusion – analyze results **ALL hypotheses must be testable to be considered scientific and results should be repeatable

Inductive vs Deductive Reasoning Inductive reasoning is making a general statement based on a number of observations. Used to form hypothesis Deductive reasoning is making a specific statement based in a general statement Used to form a testable prediction “ If hypothesis is correct then…”

Experiment Used to test hypothesis If hypothesis is correct it should yield predictable results. A hypothesis is “supported” when it yields predictable results Experimental group tests the variable in the hypothesis Control group compares the results without the experimental variable.

Important consideration of results If hypothesis is supported one must show that predicted results are not due to chance. To reduce bias in an experiment on should collect quantitative (measurable) data.

Importance of publishing All results of a scientific study should be reported Introduction: Explanation of topic being studied, past research, hypotheses being considered etc. Methods used in the experiments. Results and analysis of experiment Discussion of results – relevance in a larger context

1.2 Major Themes in Biology

Properties of life Ordered structure - cells, organs etc. Detect and respond to stimuli Reproduction – pass on hereditary material (in DNA) Growth and Development Maintenance – Homeostasis Process energy – necessary for metabolism

Levels of organization of living things Cells – smallest living unit Tissues – group of cells with the same function Organs – groups of different tissues work together Organ system – groups of organs that work together to one purpose Organism

Levels of organization Population – group of members of the same species Community – all the different species in an area Ecosystem all the living and non living parts of a area Biosphere – all places on Earth were life exists.

Phylogeny and Universal Common Ancestor One major theme in biology is that present day species evolved from distinctly different organisms. Though diverse, all species share certain structural and genetic similarities Common ancestor is a hypothesized “first” cell from which all species evolved. A Phylogeny is a hypothesis which depicts the relationships of groups of species.