biology in the 21 st century chapter 1. characteristics of science for biology 1.design and conduct...

BIOLOGY IN THE 21ST CENTURY

Chapter 1

Characteristics of Science for Biology

1.design and conduct scientific investigations (GPS, ACT) (SCBI_A2005-1)2.apply standard safety practices for all classroom laboratory and field investigations (GPS) (SCBI_A2005-2)3.use technology to collect, observe, measure, and manipulate data and findings (GPS, ACT) (SCBI_A2005-3)4.use valid critical assumptions and evidence to draw conclusions (GPS, ACT) (SCBI_A2005-4)5.apply computation and skills necessary for analyzing data and developing conclusions (GPS) (SCBI_A2005-5)6.communicate scientific information, ideas, and arguments clearly (GPS) (SCBI_A2005-6)7.read scientific materials to establish context for subject matter, develop vocabulary, and to be aware of current research (GPS) (SCBI_A2005-7)8.discuss the importance of curiosity, honesty, openness, and skepticism in science and exhibit these traits in efforts to understand how the world works (GPS)

Studying Life

The word biology means the study of life.

A biologist is a scientist who uses a scientific method to study the living world.

All living things and all places they are found on Earth make up the biosphere.

Biodiversity is the variety of life within an area.

Interactive Review: Life

http://www.classzone.com/cz/books/bio_07/resources/htmls/interactive_review/bio_intrev.html

Complete this interactive review using your virtual

textbook at home. Concept maps are an

excellent way to organize your thoughts and review

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Characteristics of Living Things

Living things share several characteristics:1. Made up of units called cells

2. Reproduce

3. Based on a universal genetic code

4. Grow and develop

5. Obtain and use materials and energy

6. Respond to their environment

7. Maintain a stable internal environment

8. Change over time

Reproduction

All organisms produce new organisms through a process called reproduction: Sexual: two cells from different parents

unite to produce the first cell of the new organism

Asexual: the new organism has a single parent

Based on a Universal Genetic Code

With minor exceptions, the DNA genetic code determines the inherited traits of every organism on Earth. Deoxyribonucleic acid

With asexual reproduction, offspring and their parents have the same traits

With sexual reproduction, offspring differ from their parents in some ways

Growth and Development

Every type of organism has a distinctive life cycle – a particular pattern of growth and change occurring over the organism’s lifetime: Growth (increase in size) Development (cells in an organism not only

increase in number but also become different)

Need for Materials & Energy

Organisms use energy and a constant supply of materials to grow, develop, and reproduce Materials & energy are also

needed just for an organism to stay alive

Metabolism is the combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes

Response to the Environment

Organisms live in constantly changing environments Amount of light and temperature can vary from day to day Nearby living and nonliving things can change Organisms can make changes to their environment

Each organism responds to environmental changes in its own way

Examples: Plants tend to grow in a direction toward a source of light

(phototropism). Birds fly south for the winter.

Maintaining Internal Balance

The process by which organisms keep their internal conditions relatively stable is called homeostasis This condition is

constantly being threatened by changes in the environment

If homeostasis is disrupted in a major way, an organism cannot survive

Evolution

As a group, any given kind of organism can evolve, or change over time Changes are not

generally significant over a few generations, but over thousands or millions of years, changes can be dramatic

The ability of a group of organisms to change over time is invaluable for survival in a world that is always changing

Critical Thinking: Connecting Concepts Plants generally grow in the direction of a light

source. This phenomenon is called phototropism. What characteristic of life does this illustrate?

Many desert animals, such as rabbits, have large ears that provide a large surface area for heat to escape. What characteristic of life does this illustrate?

What are the advantages and disadvantages sexual and asexual reproduction?

Phototropism illustrates response to the environment.

Having large ears for heat escape illustrates evolution.

Sexual provides genetic variation, but is costly in terms of energy/metabolism. Asexual is quick and relatively inexpensive, but provides no genetic variation.

Interactive Review: Biological Themes





material!

What is Science?

How is science different from other human endeavors?

1. Deals only with the natural world2. Scientists collect and organize information

in an orderly way in search of patterns & connections between events

3. Scientists propose explanations that can be tested by examining evidence

4. What is the goal of science? To investigate and understand nature, to explain events in nature, and to use those explanations to make useful predictions.

The Scientific Process: Observation

The first step in the scientific process is making observations

Involves using one or more of the senses to gather information

The information gathered is called evidence, or data

It is important when making observations to be objective and avoid bias

Observations can be classified into 2 types:1. Quantitative (involves numbers & measuring)2. Qualitative (involves characteristics not easily

measured or counted)

The Scientific Process: Question or Inference

Observations are usually followed with questions or inferences. Question: who, what, why, where, when,

how… regarding phenomena observed Inference: a logical interpretation based

on prior knowledge and experience

The Scientific Process: Hypothesis

A hypothesis is a possible general explanation for a set of observations or an answer to a scientific question In science, a hypothesis is useful only if it can be

tested Hypotheses must be falsifiable

Hypotheses may arise from prior knowledge, logical inferences, or educated guesses

Hypotheses are tested via controlled experiments

The Scientific Process: Predictions

Following a general hypothesis, a specific prediction is usually made. Like hypotheses, predictions must also be testable

and falsifiable Example: Hypothesize that there is a difference

in the age of the trees between the north side of the hill and the south side of the hill. Specifically predict that the trees on the north side are older.

The Scientific Process: Experiment

Scientists usually test hypotheses and predictions with unbiased, controlled experiments Controlled experiments test ONLY ONE variable at a

time The experiment may support or refute the hypothesis No matter the outcome, a tested hypothesis has value

in science because it helps researchers advance scientific knowledge

The Scientific Process: Concept Map

How Scientists Work: Setting Up a Controlled Experiment

Whenever possible, a hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged,

or controlled This type of experiment is called a controlled

experiment Manipulated variable (independent) Responding variable (dependent)

A control group should always be specified – this is the group to which you will compare your experimental group

How Scientists Work: Drawing a Conclusion

Scientists use the data from an experiment to evaluate the hypothesis and draw a solid conclusion They use evidence to determine whether or

not a hypothesis was supported or refuted

How a Theory Develops

As evidence from numerous investigations builds up, a particular hypothesis may become so well supported that scientists consider it a theory

In science, the word theory applies to a well-tested explanation that unifies a broad range of observations in the natural world

Scientific Laws & Theories

Scientific laws describe what nature does under certain conditions, and will predict what will happen as long as those conditions are met Often mathematically defined

Scientific theories explain how nature works Are generally non-mathematical

Scientific Laws & Theories

Commonalities between a scientific law and theory:

1. BOTH are based on tested hypotheses

2. BOTH are supported by a large body of empirical data

3. BOTH help unify a particular field

4. BOTH are widely accepted by the vast majority of scientists within a discipline

5. BOTH could be shown wrong at some time if there are data to suggest so

Data Analysis: Qualitative & Quantitative

Critical Thinking: Connecting Concepts Why is the statement “all life is made of

cells” an example of a theory. Explain.

When first proposed, the idea that all life is made of cells changed the way scientists thought about what defines an organism. Not only did it encompass all accumulated evidence, but it also provided a framework for new investigations.

Interactive Review: Scientific Thinking





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