BIO Lesson 2

What is a hypothesis?

A testable explanation for an observation or real-world phenomenon.

What makes a good scientific hypothesis?

It should be plausible, logical, informed by observations, and falsifiable/testable.

What does falsifiable mean?

There must be a possible observation or experiment that could show the hypothesis is wrong.

Can a scientific hypothesis ever be proven with 100% certainty?

No. Scientific evidence can support a hypothesis, but cannot establish it as absolutely proven.

What is a prediction?

An expected result that follows the hypothesis.

What format can be used for a prediction?

If… then…

How are a hypothesis and a prediction different?

A hypothesis explains what might be happening; a prediction states what you expect to observe if the hypothesis is correct.

What are the major steps of the scientific method in order.

Make an observation → hypothesis → prediction → tests → observe/measure -→ analyze data → support/reject/modify hypothesis → communicate

Why is observation important when developing a hypothesis?

Science explains the natural world using observations and measurable data, so observations provide the basis for asking questions and developing hypotheses.

What happens after data are collected?

The data are analyzed to determine whether they support, reject, or require modification of the hypothesis.

What happens if the data do not support a hypothesis?

They hypothesis may be rejected or modified based on the new evidence.

What is a variable?

A factor in an experiment that can change.

What is the dependent variable?

The variable the researcher measures.

What is the independent variable?

The variable the researcher changes/manipulates.

Which variable is considered the cause?

Independent variable

Which variable is considered the effect?

Dependent variable.

What is a control group?

A group in which the independent variable has not been manipulated and which provides a comparison for the treatment group.

What is a treatment group?

The group exposed to the experimental manipulation/independent variable

Why is the control group important?

It provides a baseline for comparison so researchers can determine whether the independent variable caused a change

Ideally, how should the treatment and control groups differ?

They should differ in the independent variable while other relevant conditions are kept as similar as possible.

What is experimental bias?

A systematic influence that can distort the results or interpretation of a study.

What are the three strategies for reducing bias?

Large sample size, random sampling, and blinding the data.

Why is a large sample size useful.

It reduces the influence of unusual individuals and makes results more representative.

Why is random sampling useful?

It helps ensure the sample is more representative and reduces systematic selection bias

Why is blinding useful?

It can reduce the influence of expectations or researcher interpretation on results.

What is a scientific claim?

A statement about how the world works that can be tested using experiments and the scientific process

What makes a claim scientifically testable?

It must make a statement about the world that can be investigated with observations or experiments

Why is scientific literacy important?

It helps you evaluate claims and makes you less likely to accept false claims that could negatively affect your life or health

What should you look for when evaluating whether a claim is scientific?

Evidence/data, how the data were collected, whether the claim is testable/falsifiable, whether the sample is representative, whether bias is present, whether results can be replicated, and whether the conclusion is supported by the data.

Why should you be cautious about scientific claims made on social media?

Social media claims may not have been peer-reviewed or independently checked and can contain bias, an agenda, or insufficient evidence.

Why is replication important.

Repeating research helps determine whether a result is reliable rather than a one-time finding.

What is correlation?

A relationship association between two variables

What is causation?

A situation where change in one variable directly produces a change in another.

Does correlation prove causation?

No.

Why doesn’t correlation prove causation?

The variables may both be influenced by another factor, or the relationship may be coincidental.

What is a third variable?

Another factor that influences both correlated variables may explain their relationship.

What should a scientific conclusion do?

State what the data indicate and whether the hypothesis is supported

What is a scientific fact?

A repeatable observation of an aspect of the natural world

What is a scientific theory?

A group of related hypotheses supported through multiple lines of investigation

Does “theory” in science mean a random guess?

No. A scientific theory is strongly supported by evidence from multiple investigations

What is peer review?

Evaluation of scientific work by other scientists before publication.

Why is peer review important?

It helps identify problems such as insufficient evidence, errors, fraud, or bias before research is published

Why does peer review matter to public trust in science?

It helps increase confidence that published research has been evaluated for problems and supported by appropriate evidence.

What is a descriptive observational study?

A study that reports what is observed or found

What is an analytical observational study?

A study that examines patterns or relationships in observations

What is a major difference between an observational study and an experiment?

In an experiment, researchers manipulate an independent variable; in an observational study, researchers observe without manipulating the variable.

What is a null hypothesis?

A hypothesis that says there is no effect, no difference, or no relationship between the variables. Meant to be rejected. Ex. zebra stripes have no effect on the number of insect bites zebras receive

What is an alternative hypothesis?

It says that there is an effect, difference, or relationship between the variables, Hypothesis supported after the null is rejected.