Chapter 1

Invitation to biology

Learning objective

• To explore several aspects of biology

Learning outcomes

• To explain the level of organization

• To discuss the unity of life

• To explain the diversity of life

• To explain the classification system

• To discuss the scientific approach to study nature

• To explain the philosophy of science

Overview

• The Science of Nature

• How Living Things Are Alike

• How Living Things Differ

• Organizing Species Information

• The Nature of Science

• Philosophy of Science

BIOLOGY =

Scientific and systematic study

of life

1.1 The Science of Nature

• All matter consists of atoms, which combine as molecules

• Organisms are individuals that consist of one or more cells

• Cells of larger multicelled organisms are organized as tissues, organs, and organ systems

Organization Among Organisms

• A population is a group of individuals of a species in a given area

• A community is all populations of all species in a given area

• An ecosystem is a community interacting with its environment

• The biosphere includes all regions of Earth that hold life

Life Vs nonlife

• All things (living and non living) consist of the atoms then joins as molecules

• Unique properties of life emerge as certain molecules and organized into cells

• Higher levels of life’s organization include multicelled organisms, populations, communities, ecosystems and biosphere

• Emergent properties occur at each successive level of life’s organization

KEY CONCEPTS:

LEVELS OF ORGANIZATION

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

• “Life” emerges at the level of cells

1.2 How Living Things Are Alike

• Life has underlying unity: All living things have similar characteristics

1. Continual inputs of energy and cycling of materials maintain life’s complex organization

2. Organisms sense and respond to change

3. All organisms use information in DNA inherited from parents to function and reproduce

Organisms Require Energy and Nutrients

• All organisms require energy and nutrients to sustain themselves

• energy – The capacity to do work

• nutrient – Substance that an organism needs for growth

and survival, but cannot make for itself

Producers and Consumers

• Producers harvest energy from the environment to make their own food by processes such as photosynthesis

• Examples: ?

• Consumers eat other organisms, or their wastes and remains

• Examples: ?

sunlight energy

A Producers harvest energy from the environment. Some of that energy flows from producers to consumers.

Producers plants and other self-feeding organisms

Consumers animals, most fungi,

many protists, bacteria

Organisms Sense and Respond to Change

• Organisms keep conditions in their internal environment within ranges cells tolerate

—a process called homeostasis

• Homeostasis

– Set of processes by which an organism keeps its internal conditions within tolerable ranges

– Includes body fluid composition and temperature

Stimulation and Response

• Every organism senses and responds to conditions inside and outside itself

Organisms Use DNA

• DNA contains information that guides all of an organism’s metabolic activities, including growth, development, and reproduction

• Small variations in DNA structure give rise to differences between species and individuals

• The passage of DNA from parents to offspring is inheritance

KEY CONCEPTS:

LIFE’S UNDERLYING UNITY • All organisms are alike in key respects:

– Consist of one or more cells

– Live through inputs of energy and raw materials – Sense and respond to changes in their external and

internal environments – All function and reproduce with the help of DNA

(molecule that offspring inherit from parents; encodes information necessary for growth, survival, and reproduction)

1.3 How Living Things Differ

• Different types of organisms differ greatly in details of body form and function

• Biodiversity is the sum of differences among living things

• biodiversity

– Variation among living organisms

Diversity of Life

• Prokaryotes : Bacteria and archaeans are single-celled, and their DNA is not contained within a nucleus

• Eukaryotes (protists, plants, fungi, and animals) can be single-celled or multicelled, and their DNA is contained within a nucleus

Eukaryotes

• Protists are the simplest eukaryotes, ranging from amoebas to giant kelps

• Many fungi are decomposers, including mushrooms

• Most plants are photosynthetic producers that provide food for most other organisms

• Animals eat other organisms; they include herbivores, carnivores, scavengers, and parasites

Prokaryote - Bacteria

Prokaryote - Archaeans

Eukaryote - Protists

Eukaryote - Fungi

Eukaryote - Plants

Eukaryote - Animals

KEY CONCEPTS:

LIFE’S DIVERSITY

The world of life shows great diversity

• Many millions of kinds of organisms (species) have appeared and disappeared over time

• Each species is unique in at least one trait—in some aspect of its body form or behavior

1.4 Organizing Species Information

• Each type of organism has a unique, two-part name – The first part is the genus name

– When combined with the specific epithet, it designates a particular species

• Linnaean taxonomy (Carolus Linnaeus) sorts all species into taxa on the basis of shared traits

Carolus Linnaeus (1707-1778)

• Father of Taxonomy

• His system for naming, ranking, and classifying organisms is still in wide use today

Escherichia coli or Escherichia coli

• Genus is CAPITALIZED (written first)

• Species is lower case

• Written in Latin

• Italicized OR underlined

Scientific Name

•Genus and species

•Homo sapiens

•Homo sapiens

Linnaean Classification

3 Domains or 6 Kingdoms

Any Other Name…

• Individuals of a species share a unique set of traits

– Morphological traits

– Physiological traits

– Behavioral traits

• Species can be hard to distinguish

– “biological species concept”

1.5 The Nature of Science

1) Critical thinking is judging the quality of information before accepting it

2) Scientists make and test potentially falsifiable predictions about how the natural world works

3) Science addresses only what is observable

(1) Thinking About Thinking

• Critical thinking, the self-directed act of judging the quality of information as one learns, is an important part of science

• critical thinking

• Judging information before accepting it

• science

• Systematic study of the observable world

(2) How Science Works

• Generally, a researcher observes something in nature, uses inductive reasoning to form a hypothesis for it, then uses deductive reasoning to make a prediction about what might occur if the hypothesis is not wrong

• Predictions are tested with observations, experiments, or both

• Experiments typically are performed on an experimental group as compared with a control group, and sometimes on models

• Conclusions are drawn from experimental results, or data

• A hypothesis that is not consistent with data is modified

• Making, testing, and evaluating hypotheses is the scientific method

The Scientific Method

SCIENTIFIC METHOD

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?

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• Biological systems are usually influenced by many interacting variables

• An independent variable influences a dependent variable

Research in Field and Lab

Examples of Experiments

• Researchers use experiments to unravel complex natural processes by changing one variable at a time

– Experiments are designed in a consistent way

– Researchers change an independent variable, then observe effects of change on a dependent variable

– Helps determine cause-and-effect relationship in a complex natural system

Potato Chips and Stomachaches

Butterflies and Birds

• How do peacock butterflies defend themselves against predatory birds?

• Observation: 1. Wing-flicking shows wing spots

2. Hissing and clicking sounds

• Predictions: 1. Wing spots scare predators

2. Sounds deter birds

Fig. 1-14, p. 18

Stepped Art

a Wing spots

painted out

b Wing spots

visible; wings

silenced

c Wing spots

painted out;

wings silenced

d Wings painted

but spots visible

e Wings

cut but not

silenced

f Wings painted but

spots visible; wings

cut but not silenced

Key Concepts

• The Nature of Science

– Science helps us be objective about our observations by addressing only the observable

– It involves making, testing, and evaluating hypothes

1.6 Philosophy of Science

• Science helps us be objective about our observations because it is only concerned with testable ideas about observable aspects of nature

• Opinion and belief have value in human culture, but they are not addressed by science

About the Word “Theory”

• A scientific theory is a longstanding hypothesis that is useful for making predictions about other phenomena – it is our best way of describing reality

• A law of nature describes something that occurs without fail, but for which we do not have a complete scientific explanation

Limits of Science

• Subjective values (moral, aesthetic or philosophical) can’t be tested by the scientific method

• Science doesn’t address the supernatural, or anything beyond nature

• DNA – Deoxyribonucleic acid; carries hereditary information that

guides growth and development

• growth – In multicelled species, an increase in the number, size, and

volume of cells

• development

– Multistep process by which the first cell of a new individual becomes a multicelled adult

• reproduction – Processes by which parents produce offspring

• inheritance

– Transmission of DNA from parents to offspring

• bacterium – Member of a large group of single-celled organisms

• archaean

– Member of a group of single-celled organisms that differ from bacteria

• nucleus

– Double-membraned sac that encloses a cell’s DNA

• eukaryote – Organism whose cells characteristically have a

nucleus