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Course: High school biology > Unit 1
Lesson 1: Biology and the scientific method- Biology overview
- Preparing to study biology
- What is life?
- The scientific method
- The scientific method
- Data to justify experimental claims examples
- Scientific method and data analysis
- Introduction to experimental design
- Controlled experiments
- Biology and the scientific method review
- Experimental design and bias
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Biology and the scientific method review
Key terms
| Term | Meaning |
|---|---|
| Biology | The study of living things |
| Observation | Noticing and describing events in an orderly way |
| Hypothesis | A scientific explanation that can be tested through experimentation or observation |
| Controlled experiment | An experiment in which only one variable is changed |
| Independent variable | The variable that is deliberately changed in an experiment |
| Dependent variable | The variable this is observed and changes in response to the independent variable |
| Control group | Baseline group that does not have changes in the independent variable |
| Scientific theory | A well-tested and widely accepted explanation for a phenomenon |
| Research bias | Process during which the researcher influences the results, either knowingly or unknowingly |
| Placebo | A substance that has no therapeutic effect, often used as a control in experiments |
| Double-blind study | Study in which neither the participants nor the researchers know who is receiving a particular treatment |
The nature of biology
Biology is the branch of science concerned with the study of living things, or organisms. Biologists have identified traits common to all the living organisms that we know. Although nonliving things may show some of these properties, in order for something to be considered living, it must meet all of them.
Properties of life
- Organization: Living things are highly organized (meaning they contain specialized, coordinated parts) and are made up of one or more cells.
- Metabolism: Living things must use energy and consume nutrients to carry out the chemical reactions that sustain life. The sum total of the biochemical reactions occurring in an organism is called its metabolism.
- Homeostasis: Living organisms regulate their internal environment to maintain the relatively narrow range of conditions needed for cell function.
- Growth: Living organisms undergo regulated growth. Individual cells become larger in size, and multicellular organisms accumulate many cells through cell division.
- Reproduction: Living organisms can reproduce themselves to create new organisms.
- Response: Living organisms respond to stimuli or changes in their environment.
- Evolution: Populations of living organisms can undergo evolution, meaning that the genetic makeup of a population may change over time.
Scientific methodology
The scientific method involves making observations and asking questions.
Scientists form hypotheses based on these observations and then develop controlled experiments to collecting and analyze data. Using this data, they are able to draw conclusions and form questions for new scientific research.
Scientific method example: Failure to toast
Data from many experiments are used to create a better understanding of how the world works and develop scientific theories.
Experimental design
Experimentation is the heart of science. Scientists ask questions, gather evidence, share ideas, and analyze data.
In designing an experiment, the specific question (or questions) that the experiment is meant to answer must first be clearly identified. The independent variable and dependent variable must also be identified, since the goal of a designed experiment is to understand how one variable affects another.
A simple experiment should have only one independent variable. All other factors that could have an effect on the outcome of the experiment must be controlled or held constant. In addition, one group in the experiment should be a control group, a designated group used as a comparative reference point. This group will not have a manipulated independent variable.
Reducing errors and bias
It is important to design an experiment that leads to the most accurate results possible.
Scientists generally aim to be objective, but they are people and have their own likes, dislikes, and personal biases. Because of this, scientific data may be interpreted in different ways by different scientists.
Some ways to avoid this include:
- Having a large sample size in the experiment: This helps to account for any small differences among the test subjects that may provide unexpected results.
- Repeating experimental trials multiple times: Errors may result from slight differences in test subjects, or mistakes in methodology or data collection. Repeating trials helps reduce those effects.
- Including all data points: Sometimes it is tempting to throw away data points that are inconsistent with the proposed hypothesis. However, this makes for an inaccurate study! All data points need to be included, whether they support the hypothesis or not.
- Using placebos, when appropriate: Placebos prevent the test subjects from knowing whether they received a real therapeutic substance. This helps researchers determine whether a substance has a true effect.
- Implementing double-blind studies, when appropriate: Double-blind studies prevent researchers from knowing the status of a particular participant. This helps eliminate observer bias.
Communicating findings
In order for research to be accepted, it must be shared within the scientific community. Scientists often collaborate in groups and communicate research with other groups. This communication must follow specific guidelines to make sure that the communication is appropriate.
Publishing research findings in peer-reviewed scientific journals allows scientists to share ideas, and provides other scientists with the opportunity to evaluate and test the data analysis provided.
Things to remember
- A hypothesis is not necessarily the right explanation. Instead, it is a possible explanation that can be tested to see if it is likely correct, or if a new hypothesis needs to be made.
- Not all explanations can be considered a hypothesis. A hypothesis must be testable and falsifiable in order to be valid. For example, “The universe is beautiful" is not a good hypothesis, because there is no experiment that could test this statement and show it to be false.
- In most cases, the scientific method is an iterative process. In other words, it's a cycle rather than a straight line. The result of one experiment often becomes feedback that raises questions for more experimentation.
- Scientists use the word "theory" in a very different way than non-scientists. When many people say "I have a theory," they really mean "I have a guess." Scientific theories, on the other hand, are well-tested and highly reliable scientific explanations of natural phenomena. They unify many repeated observations and data collected from lots of experiments.
Want to join the conversation?
In the explanation for the term "placebo", what does it mean when it says it is 'used as a control'? Does it mean it is used as a treatment for the control group?(7 votes)
When for example you give someone a pill that has no therapeutic effect, that is, it has no direct physiological effect on their body unlike real medications but the patient still thinks it does, the pill can still have a psychological effect on them since they expect a positive effect on their body which itself may trigger the intended effect.
This phenomenon is called the placebo effect and needs to be taken into account when conducting certain experiments like testing the efficacy of new medications.
So when designing those experiments you intend to administer placebos (effectless substance apart from the placebo effect) to your control group to, so to speak, subtract the placebo effect from the results and only obtain data on the physiological effect of the drug.(28 votes)
if I want to know who would win in a fight: Batman or superman how would I experiment that? Do i pump one of my dogs with super powers and give the other kryptonite? please help I need to know by monday(9 votes)- Well that's tricky since superman has superpowers while batman uses gadgets so it would be hard to make it a controlled experiment the best bet would be to make a clone of a baby and give either baby the skills, memories, powers, gadgets, and knowledge that the superheroes have and send them off into battle as soon as you do this.(15 votes)
are y'all going to high school?(6 votes)
yess. 9th grade baby!(7 votes)
- Why do electronics hurt people eyes?(2 votes)
- Blue light is also another reason and glare from the screen but this can be avoided not fully but still partially by wearing anti-glare glasses or if your device has blue light filtering.(8 votes)
The meaning of the key term 'Dependent Variable' has a typo.
"The variable this is observed and changes in response to the independent variable" shouldn't 'this' be 'that'?(5 votes)
If being able to reproduce is one of the factors of life, wouldnt that make infertile people slightly less alive than the rest of the population?(1 vote)- No, because they are apart of a species that can reproduce.(9 votes)
I have a question. Why is death not considered a property of living things?(2 votes)
the reason why death is not a property of a living thing because some organisms don't die , for example an Amoeba and Bacteria don't die yet they are classified as living things. So in short death is not considered a property of living thing because some organisms that are classified as living don't die. And death is also considered what happens when all of the living things properties shut down.(6 votes)
- "*Repeating experimental trials multiple times:* Errors may result from slight differences in test subjects, or mistakes in methodology or data collection. Repeating trials helps reduce those effects."
If there is a problem in the methodology, how does repeating experiments multiple times (I assume using the same methodology) correct the error if the error in its self is specific to the methodology?(3 votes)
Not the error in the chosen method, but in the procedure. there might be human error or computer error, that's why repeating is good.(4 votes)
- there is a typo in key terms (dependent variable), it says, the variable this is observed and changes in response to the independent variable, instead of that is it says this is(3 votes)
there's no typo; that's correct. the dependent variable is what changes because of the independent variable in an experiment. the independent variable is what the experimenter(?) changes for different experiment groups, and the dependent variable is the outcome of those changes.(3 votes)
How would implementing the placebo effect help reduce bias in an experiment?(4 votes)
