Invitation to Biology

Chapter 1

1.1 Impacts/Issues:

The Secret Life of Earth

Biology

The systematic study of life

We have encountered only a fraction of the organisms that live on Earth

Scientists constantly discover new species

Extinction rates are accelerating

1.2 Lifes Levels of Organization

The building blocks (atoms) that make up all living things are the same ones that make up all

nonliving things

The unique properties of life emerge as certain kinds of molecules become organized into cells

Lifes Levels of Organization

Atom Fundamental building block of all matter

Molecule An association of two or more atoms

Cell Smallest unit of life

Organism An individual; consists of one or more cells

Lifes Levels of Organization

Population Group of individuals of a species in a given area

Community All populations of all species in a given area

Ecosystem A community interacting with its environment

Biosphere All regions of Earth that hold life

Nature and Life

Nature

Everything in the universe, except what humans

have manufactured

Emergent property

A characteristic of a system that does not appear

in any of a systems component parts

Levels of Organization in Nature

1.3 Overview of Lifes Unity

All living things have similar characteristics

Require energy and nutrients

Sense and respond to change

Reproduce with the help of DNA

Energy Sustains Lifes Organization

One-way flow of energy through the biosphere and cycling of nutrients among organisms sustain lifes organization

Energy The capacity to do work

Nutrient Substance that is necessary for survival, but that

an organism cant make for itself

Organisms and Energy Sources

Producers

Organisms that make their own food using energy

and simple raw materials from the environment

Example: plants

Consumers

Organisms that get energy and carbon by feeding

on tissues, wastes, or remains of other organisms

Example: animals

Organisms Sense and Respond to Change

Organisms sense and respond to change to keep conditions in their internal environment within a

range that favors cell survival (homeostasis)

Homeostasis

Set of processes by which an organism keeps its

internal conditions within tolerable ranges

Receptor

Molecule or structure that responds to a stimulus

Organisms Grow, Develop and Reproduce

Organisms grow, develop, and reproduce based on information encoded in DNA, which they inherit from their parents

Growth Increase in size, volume, and number of cells in

multicelled species

Development Multistep process by which the first cell of a new

individual becomes a multicelled adult

Organisms Grow, Develop and Reproduce

Reproduction

Process by which parents produce offspring

Inheritance

Transmission of DNA from parents to offspring

DNA (Deoxyribonucleic acid)

Molecule that carries hereditary information about

traits

1.4 Introduction to Lifes Diversity

The millions of species on Earth vary greatly in details of body form and function

Each species is given a unique two-part name that includes genus and species names

Species A type of organism

Genus Group of species that share a unique set of traits

Classification Systems

Classification systems group species according to traits and organize information about species

One system sorts all organisms into one of three domains: Bacteria, Archaea, and Eukarya

The eukaryotes include plants, protists, fungi and animals

Prokaryotes

Prokaryotes

Single celled organisms in which DNA is not

contained in a nucleus

Bacterium

A member of the prokaryotic domain Bacteria

Archaeans

A member of the prokaryotic domain Archaea

Eukaryotes

Eukaryotes

Organisms whose cells typically have a nucleus

Fungus

Eukaryotic consumer that obtains nutrients by

digestion and absorption outside the body

Protists

Eukaryotes that are not plants, animals, or fungi

Eukaryotes

Plant

Typically a multicelled, photosynthetic producer

Animal

Multicelled consumer that develops through a

series of embryonic stages and moves about

during all or part of the life cycle

1.5 The Nature of Scientific Inquiry

Critical thinking

Mental process of judging the quality of information

before deciding whether or not to accept it

The Scope and Limits of Science

Science is a way of looking at the natural world which helps us to communicate our experiences

without bias by focusing only on testable ideas

about observable phenomena

Science does not address the supernatural

Science

The systemic study of nature

1.6 How Science Works

Researchers make and test potentially falsifiable predictions about how the natural world works

Generally, scientific inquiry involves forming a hypothesis (testable assumption) about an observation then making and testing predictions based on the hypothesis

A hypothesis that is not consistent with the results of scientific tests is modified or discarded

Common Research Practices

1. Observe some aspect of nature

2. Frame a question about your observation

3. Propose a hypothesis (a testable explanation

of the observation)

Common Research Practices

4. Make a prediction a statement based on a hypothesis, about some condition that should

exist if the hypothesis is not wrong

5. Test the accuracy of the prediction by

experiments or gathering information (tests may

be performed on a model)

Common Research Practices

6. Assess the results of the tests (data) to see if

they support or disprove the hypothesis

7. Conclusions: Report all steps of your work and

conclusions to the scientific community

A Scientific Theory

Scientific theory

A hypothesis that has not been disproven after

many years of rigorous testing

Useful for making predictions about other

phenomena

Laws of Nature

Law of nature

Generalization that describes a consistent and

universal natural phenomenon for which we do

not yet have a complete scientific information

Example: gravity

Examples of Scientific Theories

1.7 The Power of Experiments

Natural processes are often influenced by many interacting variables

Variable

A characteristic or event that differs among

individuals

The Power of Experiments

Experiments simplify interpretations of complex biological systems by focusing on the effect of

one variable at a time

Experiment

A test to support or falsify a prediction

Experimental and Control Groups

Experimental group

A group of objects or individuals that display or

are exposed to a variable under investigation

Control group

A group of objects or individuals that is identical

to an experimental group except for one variable

Results 93 of 529 people

get cramps later

(17.6%)

89 of 563 people get

cramps later

(15.8%)

Experiment Control Group

Eats regular

potato chips

Experimental Group

Eats Olestra

potato chips

Hypothesis Olestra causes intestinal cramps.

Prediction

People who eat potato chips made with Olestra will be more

likely to get intestinal cramps than those who eat potato

chips made without Olestra

Conclusion

Percentages are about equal. People who eat potato chips

made with Olestra are just as likely to get intestinal cramps

as those who eat potato chips made without Olestra.

These results do not support the hypothesis.

Fig. 1-10, p. 14

Stepped Art

Example: Butterflies and Birds

Question

Why does a peacock butterfly flick its wings?

Two hypotheses

Exposing wing spots scares off predators

Wing sounds scare off predators

Two predictions

Individuals without spots are eaten more often

Individuals without sounds are eaten more often

Experiments and Results

Four groups of butterflies were exposed to predators (birds)

Butterflies without spots

Butterflies without sounds

Butterflies without spots or sounds

Control group

Test results support both original hypotheses

Results: Peacock Butterfly Experiment

Sampling Error

Biology researchers experiment on subsets of a group, which may result in sampling error

Sampling error

Difference between results derived from testing

an entire group of events or individuals, and

results derived from testing a subset of the group

Sampling Error

Probability

Researchers try to design experiments carefully in order to minimize sampling error

Statistically significant

Refers to a result that is statistically unlikely to

have occurred by chance