Introduction Biology Today Biology is the study of

Introduction: Biology Today

Biology is the study of living things

What is Living? What properties do all organisms possess?

Organisms are complex

Maintain internal environment

Respond to stimuli

Organisms Grow and Develop

Require molecules to obtain energy • Autotrophs (Plants) make their own molecules • Heterotrophs (Animals) must obtain these molecules

Reproduce

All Species Evolve

All organisms contain DNA • DNA contains the instructions a cell needs to survive.

Biology has added to our knowledge of the natural world

Biologists can study organisms on a variety of levels and disciplines

Organization Levels of Life (Fig. 1. 2)

Diversity of Organisms • All life is composed of cells • Cells contain DNA in the form of chromosomes which directs cell activities • Prokaryotes simple single cells with no internal structures and circular chromosomes • Eukaryotes complex cells with internal structures (organelles) and linear chromosomes

Prokaryotes and Eukaryotes

Species are organized into three Domains 1. Bacteria 2. Archaea 3. Eukarya

What Ties All of Biology Together?

Theory of Evolution

Theory of evolution ties all living organisms together. • Studies the origin of species • Studies the change in species over time • Developed mechanisms that causes these changes – Natural Selection etc. • Accounts for diversity of species living today • Accounts for the extinction of all other species

What is Science? • Fact vs. Theory • Scientific method

Fact vs. Theory • • What is a fact? Facts are observable, measurable What is a theory? Theories are explanations of natural events based on a series of observations and experiments.

What is scientific? How do scientists attempt to answer questions?

Scientific method (1. 15)

Hypothesis • Educated guess based on previous information • Inductive • Must be testable to be “scientific”

Experiment • Usually tests one variable or factor • Often there is a control group which does not include the variable • Controlled experiments – All other elements should be the same in all groups

Conclusion • Do my results support my hypothesis? – If yes more predictions and experiments – If no new hypothesis

Malt Andersson tested the hypothesis that female widowbirds will mate with males with the longest tail.

Malt Andersson’s study of Sexual selection of widowbirds (NIB)

Must publish findings • Scientists are connected by journals and meetings where they report their research. • Results of any experiment must be repeatable. • New ideas may arise from the work of others.