Invitation to Biology

Chapter 1

Impacts, Issues:

Lost Worlds and Other Wonders

Discovering new plants and animals on an

expedition to New Guinea

1.1 Life’s Levels of Organization

We understand life by thinking about nature at

different levels of organization

Nature’s organization begins at the level of

atoms, and extends through the biosphere

The quality of life emerges at the level of the cell

Making Sense of the World

Nature is everything in the universe except what

humans have manufactured

A Pattern in Life’s Organization

Atoms

• Fundamental building blocks of all substances

Molecules

• Consisting of two or more atoms

Cell

• The smallest unit of life

Organism

• An individual consisting of one or more cells

A Pattern in Life’s Organization

Population

• Individuals of the same species in the same area

Community

• Populations of all species in the same area

Ecosystem

• A community and its environment

Biosphere

• All regions of the Earth where organisms live

Levels of Organization in Nature

Levels of Organization in Nature

Fig. 1-2a, p. 4

Fig. 1-2b, p. 4

Fig. 1-2c, p. 4

Fig. 1-2d, p. 4

Fig. 1-2e, p. 4

Fig. 1-2f, p. 4

Fig. 1-2g, p. 5

Fig. 1-2h, p. 5

Fig. 1-2i, p. 5

Fig. 1-2j, p. 5

Fig. 1-2k, p. 5

Fig. 1-2 (a-f), p. 4

atom

molecule cell tissue organ organ system

Stepped Art

Fig. 1-2 (g-k), p. 5

multicelled organism population community ecosystem

biosphere

Stepped Art

Animation: Life’s levels of organization

Emergent Properties

Each level of organization in nature has

emergent properties – a characteristic of a

system that does not appear in any of its

component parts

1.1 Key Concepts:

Levels of Organization

We study the world of life at different levels of

organization, which extend from atoms and

molecules to the biosphere

The quality of “life” emerges at the level of cells

1.2 Overview of Life’s Unity

All living things have similar characteristics

• Continual inputs of energy and the cycling of

materials maintain life’s complex organization

• Organisms sense and respond to change

• DNA inherited from parents is the basis of growth

and reproduction in all organisms

Energy and Life’s Organization

Energy

• The capacity to do work

Nutrients

• Atoms or molecules essential in growth and

survival that an organism cannot make for itself

Producers and Consumers

Producers

• Acquire energy and raw materials from the

environment

• Make their own food (photosynthesis)

Consumers

• Cannot make their own food

• Get energy by eating producers and other

organisms

Organisms Sense and

Respond to Change

Organisms sense and respond to change both

inside and outside the body by way of receptors

Receptor

• A molecule or cellular structure that responds to a

specific form of stimulation

Responding to Receptors

Homeostasis

Homeostasis

• Organisms use receptors to help keep conditions

in their internal environment within ranges that

their cells can tolerate

Organisms Grow and Reproduce

Organisms grow, develop, and reproduce

using information in their DNA, a nucleic acid

inherited from parents

Information encoded in DNA is the source of an

individual’s distinct features (traits)

Same Materials, Many Products

20 amino acids are the building blocks used to

build a great variety of proteins

Instructions in DNA Guide Development

Fig. 1-5a, p. 7

Fig. 1-5b, p. 7

Fig. 1-5c, p. 7

Fig. 1-5d, p. 7

Fig. 1-5e, p. 7

1.2 Key Concepts:

Life’s Underlying Unity

All organisms consist of one or more cells, which

stay alive through ongoing inputs of energy and

raw materials

All sense and respond to change; all inherited

DNA, a type of molecule that encodes

information necessary for growth, development,

and reproduction

Animation: One-way energy flow and

materials cycling

1.3 Overview of Life’s Diversity

Of an estimated 100 billion kinds of organisms

that have ever lived on Earth, as many as 100

million are with us today

Scientific Naming

Each type of organism is given a two-part name

that includes genus and species names

Genus

• A group of species that share unique features

Species

• Individuals that share one or more heritable traits

and can interbreed (if sexually reproducing)

Scientific Naming

The heavy-beaked parrotfish, Scarus gibbus

Classification Systems

Classification systems group species by their

shared, heritable traits

All organisms are classified into three domains

• Bacteria, archaea, and eukaryotes

• Eukaryotes include plants, animals, protists

and fungi

Comparison of Life’s Three Domains

Diversity of Life

Diversity of Life

Diversity of Life

1.3 Key Concepts:

Life’s Diversity

Many millions of kinds of organisms, or species,

have appeared and disappeared over time

Each kind is unique in some aspects of its body

form or behavior

Animation: Life’s diversity

One-Way Flow of Energy and Cycling of

Materials through an Ecosystem

Fig. 1-3, p. 6

energy input,

mainly from

sunlight

A Energy inputs from

the environment flow

through producers,

then consumers.

PRODUCERSplants and other

self-feeding organisms

B Nutrients become

incorporated into the

cells of producers

and consumers.

Some nutrients

released by

decomposition cycle

back to producers.

nutrient

cycling

CONSUMERSanimals, most fungi,

many protists, bacteria

C All energy that

enters an ecosystem

eventually flows out

of it, mainly as heat.

energy output, mainly heat

C All energy that

enters an ecosystem

eventually flows out

of it, mainly as heat.

energy output, mainly heat

Fig. 1-3, p. 6

energy input,

mainly from

sunlight

A Energy inputs from

the environment flow

through producers,

then consumers.

PRODUCERSplants and other

self-feeding organisms

B Nutrients become

incorporated into the

cells of producers

and consumers.

Some nutrients

released by

decomposition cycle

back to producers.

nutrient

cycling

animals, most fungi, many protists, bacteria

CONSUMERS

Stepped Art

1.4 An Evolutionary View of Diversity

A theory of evolution by natural selection is an

explanation of life’s diversity

Variation and Mutation

Information encoded in DNA is the basis of traits

an organism shares with others of its species

Mutations are the original source of variation in

traits

Adaptation

Some forms of traits are more adaptive than

others, so their bearers are more likely to survive

and reproduce

Over generations, adaptive traits tend to

become more common in a population; less

adaptive forms of traits become less common or

are lost

Evolution and Natural Selection

Evolution is change in a line of descent

• Traits that characterize a species can change

over generations in evolving populations

Natural selection is an evolutionary process

• Differential survival and reproduction among

individuals that vary in the details of their shared,

heritable traits

Artificial and Natural Selection

1.4 Key Concepts:

Explaining Unity in Diversity

Theories of evolution, especially a theory of

evolution by natural selection, help explain why

life shows both unity and diversity

Evolutionary theories guide research in all fields

of biology

1.5 Critical Thinking and Science

Critical thinking is judging the quality of

information

Science is limited to that which is observed

• Helps minimize bias in judgments by focusing on

testable ideas about observable aspects of nature

A Guide to Critical Thinking

1.6 How Science Works

Scientists make and test potentially falsifiable

predictions about how the natural world works

Observations, Hypotheses, and Tests

Researchers make observations, form

hypotheses (testable assumptions), and make

predictions about what might occur if the

hypothesis is correct

A Scientific Approach

Research in Laboratory and Field

About the Word “Theory”

A hypothesis that is inconsistent with results of

scientific tests (evidence) is modified or

discarded

A scientific theory is a long-standing

hypothesis that is used to make useful

predictions

Examples of Scientific Theories

Some Terms Used in Experiments

Experiments

• Tests that can support or falsify a prediction

Variable

• A single characteristic in a set of individuals that

differs from the control group in an experiment

Some Terms Used in Experiments

Experimental group

• Group with a single variable characteristic to be

tested against a control group in an experiment

Control group

• Group identical to the control group, except for

the variable

1.7 The Power of Experimental Tests

Researchers unravel cause and effect in

complex natural processes by studying the

effects of one variable at a time

Potato Chips and Stomach Aches

Researchers tested the prediction that Olestra®

in potato chips causes cramps

• Experimental group: Olestra chips

• Control group: regular chips

Experiment:

Olestra and Stomach Cramps

Results Control Group

Eats regular

potato chips

Experimental Group

Eats Olestra

potato chips

Experiment Control Group

Eats regular

potato chips

Experimental Group

Eats Olestra

potato chips

HypothesisOlestra® 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

Butterflies and Birds

Why does the peacock butterfly flick its wings

when birds are near?

Researchers tested two hypotheses

• Wing spots deter predatory birds

• Hissing and clicking sounds deter predatory birds

Peacock Butterfly Defenses

against Predatory Birds

Fig. 1-11a, p. 15

Fig. 1-11b, p. 15

Fig. 1-11c, p. 15

Results: Peacock Butterfly Experiment

Asking Useful Questions

Scientists try to design single-variable

experiments that yield quantitative results

When studying humans, isolating a single

variable is not often possible

1.8 Sampling Error in Experiments

Researchers experiment on subsets of a group

• Results may differ from results of the same

experiment performed on the whole group

Sampling error is a difference between results

from a subset and results from the whole

• Small sample size increases the likelihood of

sampling error in experiments

Sampling Error

Fig. 1-12a, p. 16

Fig. 1-12b, p. 16

Fig. 1-12c, p. 16

Fig. 1-12d, p. 16

Fig. 1-12, p. 16

A) Natalie, blindfolded, randomly plucks a jelly bean

from a jar. There are 120 green and 280 black jelly

beans in that jar, so 30 percent of the jelly beans in the

jar are green, and 70 percent are black.

B) The jar is hidden from Natalie’s view

before she removes her blindfold. She

sees only one green jelly bean in her

hand and assumes that the jar must hold

only green jelly beans.

C) Blindfolded again, Natalie picks

out 50 jelly beans from the jar and

ends up with 10 green and 40 black

jelly beans.

D) The larger sample leads Natalie to assume that one-fifth of the

jar’s jelly beans are green (20 percent) and four-fifths are black (80

percent). The sample more closely approximates the jar’s actual

green-to-black ratio of 30 percent to 70 percent. The more times

Natalie repeats the sampling, the greater the chance she will come

close to knowing the actual ratio. Stepped Art

Animation: Sampling error

Summary of Life’s Characteristics

1.5-1.8 Key Concepts:

How We Know

Biologists make systematic observations,

predictions, and tests in the laboratory and in the

field

They report their results so others may repeat

their work and check their reasoning

Animation: Insect development

Animation: Three domains

Video: Finding new species