What is biology?

Bio means “life” logy mean “study” Life” emerges at the

level of cells Nature

• has levels of organization

• properties emerge at successively higher levels

Life properties Organization

• More next slide!

Metabolism• Chemical process total (more

later)

Growth• Increase in size or number

Adaptability• Adjust to changes (more later)

Evolve• Better fit the environment

Irritability• Respond to stimuli

How organisms are organized?Atoms

organized into molecules

multicelled species,

cells organized into tissues, organs, and organ systems

organisms consist of one or more cells

emergent properties life emerges at cellular level

We study the world of life at different levels of organization, from atoms and molecules to the biosphere

Organisms then group as:

Population • individuals species

• in specific area Community

• populations • in specific area

Ecosystem • community interacting

• with its environment Biosphere

• All regions of Earth that hold life

• Land, water, and atmosphere

What does life requires?

Organisms require energy and materials to sustain their organization and activities• Nutrients are

required for growth and survival

• Producers make their own food

• Consumers eat other organisms

Energy Flow and Material Cycling

Some more features of living organisms!

Organisms sense change• Receptors respond to stimulation• Responses keep internal conditions within

ranges that cells can tolerate (homeostasis)

Organization is a must!

Organisms grow and reproduce• Based on information encoded in DNA• Inheritance transmits DNA from parents to

offspring through reproduction mechanisms• Development transforms first cell into an

adult

So much unity, so many species

The world of life, past and present, shows great diversity

Classification systems organize species in ever more inclusive groups

Species: One kind of organism Each species has a two-part name

• First part: Genus name • Combined with the second part, it

designates one particular species

What are domains?

Current classification groups all species into three domains • Bacteria (single-celled prokaryotes)• Archaea (single-celled prokaryotes)• Eukarya (protists, plants, fungi, and

animals)

Bacteria

Eukarya

Archaea

What is critical thinking and science?

Critical thinking is a self-directed act of judging the quality of information as one learns

Science is a way of looking at the natural world• Helps minimize bias in judgments• Focuses on testable ideas about observable

aspects of nature Researchers generally

• Observe something in nature • Form hypotheses (testable assumptions) about it• Make predictions about what might occur if the

hypothesis is not wrong • Test their predictions by observations,

experiments, or both

What are experiments ?

Tests used to support or falsify a prediction• Variable characteristic is measured and changed• In the control group, variables do not change

Biological systems have many variables Experiments simplify observations of nature

• Focus on cause, effect, or function of one variable at a time

Researchers design experiments to minimize potential bias in interpreting results

What is a scientific theory?

A well-tested hypothesis• Explains a broad

range of observations• Can be used to make

useful predictions about other phenomena

Opinion and belief are not scientific theory