Chapter 1The Science of Biology

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1.1 What is Science?

Science – an organized way of gathering and analyzing evidence about the natural world.• It is a process, not a thing

The goals of science:• To provide natural explanations for events in the

natural world• Use those explanations to understand patterns in

nature and make useful predictions about natural events.

Science, Change and Uncertainty – Does science always “prove” anything in absolute terms?

Scientific Methodology Involves observing and asking

questions, making inferences and forming hypotheses, conducting controlled experiments, collecting and analyzing data, and drawing conclusions1. Observing and asking questions Scientific investigation begins with observation

– the act of noticing and describing events or processes in a careful, ordered way.

Scientific Methodology2. Inferring and forming a hypothesis Inference – a logical interpretation based on

what scientists already know. Hypothesis – a scientific explanation for a set

of observations that can be tested in ways that support or reject it.

Scientific Methodology3. Designing controlled experiments Controlled experiment - Whenever possible, a

hypothesis should be tested by an experiment in which only one variable is changed

Controlling variables – if variable are not controlled, researchers cannot tell which variable is responsible for the results.

Independent Variable (Manipulated) – Deliberately changed

Dependent Variable (Responding) – is observed and changes in response to the independent variable

Does adding sugar to water keep flowers fresh? I = Sugar; D = Flower freshness

Scientific Methodology Control and Experimental Groups

Control Group – exposed to the same conditions as the experimental group except for one independent variable Water without sugar

Experimental Groups – several sets

4. Collecting and Analyzing Data Data – detailed records of experimental

observations

5. Drawing Conclusions – Use experimental data to prove or disprove original hypothesis

1.2 Science in Context

Scientific Theories Scientific Theories

• A well-tested explanation that unifies a broad range of observations and hypotheses and that enables scientists to make accurate predictions about new situations.

• May become the dominant view, but no theory is the absolute truth.

Science and Society What is the relationship?

• Using science involves understanding its context in society and its limitations.

Avoiding bias• Bias – is a particular preference or point of

view that is personal, rather than scientific.• Ex: Students learn more in science class.

1.3 Studying Life

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Characteristics of Living Things

Biology – the study of life Living things:

1. Are based on a universal genetic code – DNA copied and passed from parent to offspring.

2. Grow and develop – an apple tree develops from a tiny seed.

3. Respond to their environment Detect and respond to stimuli – a signal to which

an organism responds

4. Made up of cells

Characteristics of Living Things5. Taken as a group, living things evolve Found in all aspects of living and fossil organisms,

from physical features to structures of proteins.

6. Obtain and use material and energy All organisms must take in material and energy to

grow, develop, and reproduce

7. Maintain a stable internal environment Homeostasis – relatively constant internal physical

and chemical conditions that organisms maintain.

8. Reproduce Sexual reproduction – two parents Asexual reproduction – single organism produces

offspring identical to self

Big Ideas in Biology Cellular Basis of Life

• Unicellular vs. Multicellular Information and Heredity

• Living things are based on a universal genetic code Matter and Energy

• Living things obtain and use material and energy• Matter serves as nutrients to build body structures

and fuel life’s processes• Plants = Sun; Animals = Eat plants or other animals

Growth, Development and Reproduction• All living things reproduce• Generalized cells become specialized

Big Ideas in Biology Homeostasis – Maintain stable internal

environment Evolution – As a group, living things evolve Structure and Function

• Living things have evolved to make particular functions possible Fish gills, Bird wings

Unity and Diversity of Life• All organisms are composed of a common set of

carbon-based molecules, store information in a common genetic code, and use proteins to build their structures and carry out their functions.

Big Ideas in Biology Interdependence in Nature

• All forms of life on Earth are connected into a biosphere – “living planet”

Science as a Way of Knowing• Uses observations, questions, and

experiments to explain the natural world.

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Performing Biological Investigations

Most scientists use the metric system when collecting data and performing measurements

The International System of Units

SI system, metric system

A measuring system based on units of 10.

Three nations have not officially adopted the International System of Units as their primary or sole system of measurement: Burma, Liberia, and the United States.

1 decimeter

1 centimeter

Prefix (word part) Symbol Meaning

Kilo- k 1000

Hecto- h 100

Deka da 10

Deci- d 0.1 (1/10)

Centi c 0.01 (1/100)

Milli m 0.001 (1/1000)