Introduction to Biological Concepts and Research

Chapter 1

1.1 What Is Life? Characteristics of Living Systems

Organized in a hierarchy• Each level with its own emergent properties

Contain chemical instructions• Govern structure and function

Engage in metabolic activities

1.1 (cont.)

Energy flows through; matter cycles

Compensate for changes in external environment

Reproduce and undergo development

Populations change from one generation to the next

Hierarchy of Living Systems (1)

Cells• Lowest level of organization that is alive

Organisms• Unicellular or multicellular

Populations• Groups of organisms of the same kind,

living together in the same area

Community• All populations living in an area

Ecosystems • Include communities that interact

through their shared physical environment

Biosphere• The highest level• Includes all Earth’s ecosystems

Hierarchy of Living Systems (2)

Information Flow

Living organisms have complex structures• Established by instructions coded in DNA

Information in DNA is copied into RNA• Guides production of protein molecules

Proteins carry out most activities of life

Deoxyribonucleic Acid (DNA)

Fig. 1-3, p. 3

Information Flow

Fig. 1-4, p. 4

Metabolism

The activity of obtaining and using energy• Maintenance• Growth• Reproduction

Two primary metabolic processes• Photosynthesis• Cellular respiration

Metabolism

Fig. 1-5, p. 4

Energy and Matter

Energy• Flows through the hierarchy of life• Eventually released as heat, which cannot be

used by living systems

Matter• Recycled within the biosphere

Energy Flow and Nutrient Recycling

Fig. 1-6, p. 5

Compensation for Change

Cells and organisms use receptors to detect changes in environment

Triggers a compensating reaction that allows the organism to survive

Reproduction and Development

Organisms reproduce

Offspring develop into mature, reproductive adults

Evolution

Populations undergo biological evolution as generations replace one another over time

1.4 Biological Research

Biologists conduct basic and applied research using the scientific method

Research includes collecting observational and experimental data

Hypotheses may be tested with controlled experiments

Or, a null hypotheses may be used to evaluate observational data

1.4 (cont.)

Model organisms may be used to study fundamental biological processes

Molecular techniques have revolutionized biological research

Scientific theories are ideas that have withstood the test of time

Basic and Applied Research

Basic research advances our knowledge of living systems

Applied research solves practical problems

Data

Observational data describe biological organisms or the details of biological processes

Experimental data describe results of an experimental manipulation

Hypotheses

Working explanations developed by scientists about the relationships between variables

Scientific hypotheses must be falsifiable

Experiment

A well-designed experiment• Considers alternative hypotheses• Includes control treatments and replicates

Modern Techniques

Model organisms• Easy to maintain in the laboratory• Subjects of much research

Molecular techniques• Manipulation of specific genes in the laboratory• Allow detailed analysis of DNA of many species

A Scientific Theory

A set of broadly applicable hypotheses• Completely supported by repeated tests under

many conditions and different situations

Theory of evolution by natural selection• Explains how life evolved through natural

processes• Central importance to biology