Transcript 1-1 What is Science?

1-1 What is Science?
• OBJECTIVES:
– Explain what the goal of science is
– Explain what a hypothesis is
What Science Is and Is Not
• The goal of science is to investigate and
understand the natural world, to explain events
in the natural world, and to use those
explanations to make useful predictions
• Science:
– Deals only with the natural world
– Collects and organizes information carefully
– Proposes explanations that can be tested by
examining evidence
Thinking Like a Scientist
• Scientists begin by making observations
about events or processes
• The information gathered through
observations is called data
• Data can be quantitative (numbers) or
qualitative (descriptions)
• Scientists use data to make inferences logical interpretations based on prior
knowledge or experience
Explaining & Interpreting Evidence
• Hypothesis: A scientific explanation for a
set of observations
• Hypotheses must be able to be tested with
controlled experiments or by gathering
more data
Science as a Way of Knowing
• Science is not unchanging knowledge – it is
an ongoing process
• Scientific understanding is always changing
due to new tools, techniques, and discoveries
• The focus of biologists is on living systems
that range in size from the invisibly small to
the size of the entire planet
Science & Human Values
• An understanding of science and the
scientific approach is is essential in order to
make decisions about many current issues
–
–
–
–
–
Smoking & lung disease
Cancer
AIDS
Heart Disease
Environmental concerns
1-1 Section Assessment
1. What does science study?
2. What does it mean to describe a scientist
as skeptical? Why is skepticism
considered a valuable quality in a
scientist?
3. What is the main difference between
qualitative and quantitative observations?
1-1 Section Assessment
4. What is a scientific hypothesis? In what two
ways can a hypothesis be tested?
5. Is a scientific hypothesis accepted if there is no
way to demonstrate that the hypothesis is
wrong? Explain your answer.
6. Suppose a community proposes a law to require
the wearing of seatbelts in all moving vehicles.
How could scientific research have an impact on
the decision?
1-2: How Scientists Work
• OBJECTIVES:
– Describe how scientists test hypotheses
– Explain how a scientific theory develops
Designing an Experiment
• Asking Questions
• Forming a hypothesis
• Setting up a controlled experiment
–
–
–
–
Use only one variable
Control (keep unchanged) all others
Manipulated variable is changed
Responding variable is observed
• Recording & analyzing results
• Drawing conclusions
* Francesco Redi (1668)
• Tested the hypothesis of spontaneous generation
(life could arise from nonliving matter)
• Uncovered jars with meat (variable)
• Covered jars with meat (control)
• Maggots only formed in the uncovered jars –
spontaneous generation did not occur
Publishing & Repeating Investigations
• Publishing data is important so other can repeat
the same experiments
• Needham (1700’s) – used gravy and showed that
microorganisms could arise spontaneously under
the right conditions
• Spallanzani reviewed Needham’s work and saw
that it was flawed - no spontaneous generation
• Pasteur also showed that life can only come from
other living things
When Experiments are not Possible
• Field studies can be used for wild creatures
• Testing on humans?
• Try to identify and control as many
variables as possible
How a Theory Develops
• A theory develops when a hypothesis
becomes well-supported (Ex: Theory of
Biogenesis)
• In science, a theory is a well-tested
explanation that unifies a broad range of
observations
• Theories can be revised or replaced if new
evidence is discovered
1-2 Section Assessment
1. Why is Redi’s experiment on spontaneous
generation considered a controlled
experiment?
2. How does a scientific theory compare with
a scientific hypothesis?
3. How do scientists today usually
communicate their results and
conclusions?
1-2 Section Assessment
• 4. How did the design of Pasteur’s flask
help him successfully refute the hypothesis
of spontaneous generation?
• 5. Evaluate the impact of Pasteur’s research
on both scientific thought and society.
What was the effect of Pasteur’s
investigations on scientists’ ideas and
peoples lives?
1-3: Studying Life
• OBJECTIVES:
– What are the characteristics of living things?
– How can life be studied at different levels?
• Biology - The study of life -or- the science
that seeks to understand the living world
Characteristics of Living Things
•
•
•
•
•
Made of cells (enclosed collections of living matter)
Reproduction (sexual = 2 parents, asexual = 1)
Based on a genetic code (DNA)
Growth and development
Need for materials and energy (metabolism- chem.
reactions that build or break down materials)
• Response to the environment (stimulus)
• Maintaining internal balance (Homeostasis- keeping
internal conditions constant)
• Evolution (groups of organisms change over time)
Characteristics of Life
Characteristics of Life
Branches of Biology
•
•
•
•
•
•
•
Molecules - Groups of atoms
Cells - Smallest functional unit of life
Groups of cells - tissues, organs, organ systems
Organism - Individual living thing
Population - Groups of organisms of one type
Community - All populations in an area
Ecosystem - Community & nonliving
surroundings
• Biosphere - Contains all ecosystems
Biology in Everyday Life
•
•
•
•
Appreciation of life
Food and health
Environmental threats
Quality of life
1-3 Section Assessment
1. Describe five characteristics of living
things
2. What topics might biologists study at the
community level of organization?
3. Compare sexual reproduction and asexual
reproduction.
4. What biological process includes chemical
reactions that break down materials?
1-3 Section Assessment
5. What is homeostasis? Give an example of
how it is maintained?
6. Suppose you feel hungry, so you reach for a
peach you see in a fruit bowl. Explain how
both external and internal stimuli are
involved in your action.
1-4: Tools & Procedures
• OBJECTIVES:
– What measurement system do most scientists
use?
– How are light microscopes and electron
microscopes similar? How are they different?
A Common Measurement System
• Scientists use the metric system which is
based on units of 10
• SI is a revised version of the metric system
• Units used include meters (m), kilograms
(kg), liters (L), and Celsius degrees (oC)
Analyzing Biological Data
• Tables and graphs make patterns in data
easier to recognize and understand
• Computers can be used to organize and
collect data
Microscopes
• Two issues – magnification and sharpness
• Light microscopes
– Magnify up to 1000 times
– Compound uses two lenses
• Electron Microscopes
– Use electrons instead of light
– 1000 times more detailed than light microscope
– SEM vs. TEM
Laboratory Techniques
• Cell Cultures
– A single cell is placed in a nutrient solution
– The cell produces a group of cells called a cell
culture
– Can be used for tests
• Cell Fractionation
– Used to separate one part of the cell from the rest of
the cell
– Can study one part of the cell
– Uses a centrifuge to spin the material
Working Safely in Biology
• Read and understand all procedures before
you start an activity
• Follow the teacher’s directions exactly
1-4 Section Assessment
1. Why do scientists use a common system
of measurement?
2. What is different in the way light
microscopes and electron microscopes
produce images?
3. What types of objects can be studied with
a light microscope? What types can be
studied with an electron microscope?
1-4 Section Assessment
4. Describe the technique and purpose of cell
fractionation.
5. It has been said that many great discoveries
lie in wait for the tool needed to make them.
What does this statement mean to you? If
possible, include an example in your
answer.