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Biology & the Scientific Method
Transcript of Biology & the Scientific Method
The scientific method Levels of Biological Study Biosphere all parts of the planet inhabited by living things Ecosystem all of the living and nonliving things in an area Organism an individual living thing Cells life's basic unit of structure and function DNA & Genes chemical responsible for inheritance units of inherited information Diversity of Earth's Species a distinct form of life 1.5 million identified
1 million are insects Classifying Life Three Domains sorting organisms into groups
fewer organisms in each group as categories get more specific Canis familiaris Canis Canidae Carnivora Mammalia Chordata Animalia Eukarya most specific least specific broadest category of classification Unicellular Prokaryotic Multicellular Eukaryotic composed of one cell cell that lacks a nucleus composed of many cells cell with a nucleus archaebacteria are extremophiles, living in harsh environments such as hot springs Reading a dichotomous key
"di-" means 2 each group has 2 options
must match one description or the other a number means jump to that group a name means that is the name of the object/organism descriptions are numbered in pairs with an "a" and "b" option Cellular
of Life Ten Themes of Biology Biological
Systems Form &
& Life Regulation Adaptation
& Evolution Biology
& Society Scientific
Inquiry a combination of parts forming a more complex organization The components of a system work together to perform complex processes a plant's reproductive system consists of many parts all of the organs in the digestive system must function together to digest food an
organisms rather than organs all living things are composed of cells
multicellular organisms have specialized cells
cells form groups that enable the organism to perform its life processes many cells form tissue specialized cells perform specific jobs in the organism many tissues form organs many organs form an organ system many organ systems work together to form an organism each part of an organism is constructed to perform a particular function The ears of a jackrabbit serve 2 functions:
capture sound for enhanced hearing
blood vessels allow heat to escape in hot weather "Like begets like."
organisms produce offspring that resemble themselves
information is passed via genes Plants interact with the environment by performing photosynthesis.
They utilize water, carbon dioxide, and light to produce oxygen and sugar. Stimulus & Response Living things respond to stimuli
an organism reacts to elements of its surroundings, including:
change of seasons elements such as carbon are exchanged between organisms as they interact with their environment Energy flows through an ecosystem in a regular pattern all energy comes from the sun it is passed from organism to organism in a food chain produces the food for the rest of the ecosystem eats (consumes) the food made by the producers organisms have mechanisms to regulate their internal conditions Homeostasis "steady state"
ability of living things to keep their internal environment stable
humans sweat to regulate ccool body temperature
shiver to warm up
dogs pant when hot process of change an inherited trait that increases the ability of an organism to survive due to natural selection Natural selection process by which beneficial adaptations are passed on
better adapted organisms produce more offspring
poorly adapted organisms produce fewer offspring
can produce different results in different populaitons a population is a group of organisms of the same species living in an area addresses:
how biology and its discoveries impact humans
how humans impact the natural world issues include:
improving crops Biology follows a set of rules
using obervations or experiments to find the answers
more in Chapter 2 Discovery Science Hypothesis-Based Science What happens next? What is science?
from Latin word "to know"
a way of knowing
answers questions about the natural world
key feature is inquiry--asking questions and seeking answers Observations
Data use of the senses to gather information recorded observations Quantitative
deals with numbers
a number is a quantity
often obtained by taking measurements Qualitative
can't be stated as a number
ex: color, the way someone acts, hardness, appearance should be:
recorded at consistent intervals (1 hour, 2 days)
reliable Data is often recorded in tables. This makes finding patterns and supporting conclusions easier. Inferences & Generalizations logical conclusion based on observations observation inference one two Someone is at the door. Mom saw me sneaking out. I'm going to get grounded. The doorbell rang. (cc) image by anemoneprojectors on Flickr putting together many specific observations to reach a general conclusion Examples:
girls stop growing earlier than boys
it is dark at midnight **Important!**
Generalizations describe patterns. There will be exceptions! What is discovery science? describes natural phenomena or structures through careful note taking and observation
experiments not possible
sometimes accidental Jane Goodall's research on chimpanzees was based primarily on observations. Penicillin was discovered by accident when mold grew on a bacterial culture. Fleming observed the bacteria didn't grow near the mold. Usually referred to as the scientific method.
Ordered process to answer questions posed by discovery science.
Order of steps may vary, but certain rules must be followed. Conducting a Controlled Experiment Title Problem Hypothesis Prediction Should describe the problem or experiment
often the last thing written in a lab report Examples:
The Effect of Soap on Plant Growth
Comparing Fish Food Brands The question the experiment is trying to answer
generated as a result of observations Examples:
Does soap kill plants?
What type of food do goldfish prefer? an educated guess explains what you think the experiment will show Examples:
Plants exposed to soap will die.
Fish prefer Miller brand flakes. an "if...then..." statement that explains what will happen if the hypothesis is correct.
IF: state the variable you will change to test the hypothesis
THEN: state what you think will happen. Examples:
If I water plants with soapy water, then the plants will die.
If I feed the fish different foods, then they will eat more of the Miller brand flakes. Materials Procedure Data Conclusion Sources of Error list EVERY item needed for the experiment
another scientist must be able to replicate your experiment
list the number or amount of each material Number steps and write them in complete sentences.
Write every step of the experiment.
Include control: the group you will compare your experimental group to.
Explain how measurements will be taken as well as how often.
Include any safety precautions. Assume your audience knows nothing.
Enough detail for another scientist to replicate experiment. Water one group of plants with plain water.
Change only one variable! Measure plants in cm every 5 days.
Count the number of flakes consumed in 2 minutes. Wear safety goggles.
Wash hands after handling soap solutions. Usually reported in the form of a chart or graph. Graph title:
brief and descriptive
includes both variables X axis Y axis Independent variable:
scientist controls this
even spacing along axis Dependent variable:
usually what is measured
"depends" on the independent variable
scale proceeds in even intervals (5, 10, 15; 0.5, 1.0, 1.5, etc.) Variable:
condition that varies in an experiment Axis labels include variable and units Key each group has a different color or symbol interprets the data The data will either SUPPORT or CONTRADICT the hypothesis. (Never use "prove.")
provide evidence from the experiment to support the conclusion
should also discuss possible sources of error must be
falsifiable able to be tested able to be proven false anything that could affect the outcome of the experiment
"I measured wrong" is not acceptable. Examples:
one of the plants was sick
one of the plants received more light than the others Communicate
Evidence Models Theories Limitations
of Science Technology application of science for a purpose Natural explanations for natural phenomena Science does not address: morality personal
preference supernatural a representation of how we understand a process or idea Can be:
Helps to understand difficult concepts. Scientific discoveries must be communicated to other scientists to be scrutinized. Ways to communicate:
Internet Other scientists must be able to:
evaluate your data for errors
repeat your experiment
obtain similar results
This is why communication is critical! Science values skepticism! well-tested explanation based on a large volume of data Don't confuse this with the everyday meaning of theory! a scientific theory has been tested over and over again
data has not contradicted it!
BUT it could still be invalidated by a new finding!
OR new data could cause scientists to refine the theory cell theory gravity atomic theory DNA Divided into four kingdoms Plantae Animalia Fungi Protista At what organizational levels can biology be studied? How are living things similar and different?