CHAPTER 1

The Science of Life

Section 1-1 The Study of Life Objectives

1. List six unifying themes in biology.

2. Explain how organisms get the energy they need.

3. Describe the main difference between the structure of a living thing and a nonliving thing.

In the beginning . . .

• First forms of life on earth– arose 3.5 bya – prokaryotic, unicellular, heterotrophic

Themes in Biology

• Cell structure and function

unicellular vs. multicellular

What is differentiation?

prokaryotic vs. eukaryotic

common cell parts

Themes in Biology

• Stability and Homeostasis– Organisms must control conditions such as

temperature, water content, food intake, and pH

Homeostasis – constant internal environment

Themes in Biology

• Reproduction and Inheritance– The molecule of heredity is DNA

Gene – section of DNA that codes for the development of a trait

Two types of reproduction• Sexual and Asexual

Themes in Biology

• Evolution– Populations of organisms change over time– Natural selection is the mechanism by which

evolution occurs

Themes in Biology

• Interdependence of Organisms– Ecology is the study of the interactions of

organisms with one another and with their environment

Ecosystems – environmental communities

Themes in Biology

• Matter, Energy , and Organization– Autotrophs vs. Heterotrophs

Section 1-2 The World of Biology Objectives

1. List six characteristics of life.

2. Describe how a living things is organized.

3. Explain why all living things on Earth are not yet well understood.

Characteristics of Life

• Cells– Unicellular– Multicellular

Characteristics of Life

• Organization

Organism

System

Organ

Tissue

Cells

Organelles

Molecules

Atoms

Biosphere

Biome

Ecosystem

Community

Population

Characteristics of Life

• Energy Use– Metabolism- the sum of all the chemical

processes that occur in an organism• Two Types• Anabolism

– building complex molecules from simpler ones – ex: photosynthesis

• Catabolism– breaking down complex molecules into simpler ones– ex: cellular respiration

Characteristics of Life

• Flow of Energy in an Ecosystem

Solar energy Chemical energyAUTOTROPHS HETEROTROPHS

Mechanical energy

Characteristics of Life

• Homeostasis– Necessary for survival– A reaction (response) to a change in the

environment (stimulus) helps us to maintain homeostasis

Characteristics of Life

• Growth– Results from

• Cell enlargement

• Cell division

– Is necessary for the development of an adult organism

Characteristics of Life

• Reproduction– Is necessary for the survival of the species– Two types

• Asexual– One parent cell divides to form two identical daughter

cells.

• Sexual– Two cells unite to form a new organism, different from

either parent cell.

The Living World

• Difficulties involved in studying all living things – Inaccessibility to all organisms– Some organisms are so small– Few of some species exist

Section 1-3 Scientific Methods Objectives

1. Define and give examples of observing, measuring, organizing and analyzing data, inferring, and modeling.

2. Explain the relationship between hypothesizing, predicting, and experimenting.

3. Explain why good communication is so important in science.

4. Describe the methods that scientists use in their work.

Scientific Methods

• Observing

Scientific Methods

• Asking a Question/Stating the Problem

• Collecting Data/Background Information– 1. Observing– 2. Measuring– 3. Sampling– 4. Organizing data using graphs, charts, tables,

or maps

Scientific Methods

• Hypothesizing

Hypothesis – TESTABLE statementPrediction – a statement made in advance that

states the results that will be obtained from testing a hypothesis, if the hypothesis is supported

If . . . Then . . .

Scientific Methods

• Experimenting

– Process by which a hypothesis is tested under controlled conditions

– Data which is collected and organized must then be analyzed

Scientific Methods

• Drawing Conclusions

If data are reliable, the hypothesis is supportedIf data are NOT reliable, the hypothesis is

rejected

Modeling and inferring may be used to help draw conclusions

Scientific Methods

• A hypothesis that is repeatedly tested and supported may become a THEORY!

?? What is the difference between

a theory and a law ??

Scientific Methods

• Communicate the results

review

Controlled Experiments

• Two Groups

– Control Group• Differs from the experimental group in only ONE way• Is used as a standard for comparison

– Experimental Group• Differs from control group by one factor called the INDEPENDENT

VARIABLE• The DEPENDENT VARIABLE is observed or measured in both

groups

review

Section 1-4 Microscopy & Measurement Objectives

1. Compare light microscopes and electron microscopes in terms of magnification and resolution

2. Explain the advantage of using the International System of Units (SI)

Microscopes

• Magnification and Resolution

– Magnification – the apparent increase in an object’s size

– Resolution – the ability to see detail

Microscopes

• Light microscopes– Uses light and lenses to illuminate and magnify

the image

• Electron microscopes– Uses a beam of electrons to magnify the image

Measurement

• Base Units– Length, mass, time chart

• Derived Units– Area, volume, mass density, specific volume,

temperature

• Other Units– Minute, hour, day, liter, metric ton