Biology Review

unit 1 Concept 0

-Scientific method: Is a step-by-step process used by scientists to investigate questions, gather evidence, and draw conclusions based on experiments and observations.

-The 6 steps are:

Observation: Identifying a problem or question based on initial research.
Question: Gathering existing information related to the question.
Hypothesis: Formulating a testable prediction or educated guess.
Experiment: Conducting tests to collect data and examine the hypothesis.
Data: Evaluating the data collected to determine if it supports the hypothesis.
Conclusion: Drawing final insights and deciding on the next steps based on the analysis.

Hypothesis: Predictions that can be tested by recording more observations or experiments.

Often heard as: “if…,then..(because…)” but it doesn’t have to be in this format.
“if” - the manipulated variable(IV)
“Then” - the responding variable (DV)
“Because”- optional explanation

Results can either support to refute the hypothesis
(never say, “the hypothesis is correct”

Always start with a null hypothesis
whats a null hypothesis? A null hypothesis is a statement of "no effect" or "no difference" that researchers aim to disprove in statistical testing. It's the default assumption that researchers start with.
it provides a basline that scientists can test against, helping them determine if their results are significant or due to chance.
Example: Null Hypothesis: H0: There is no difference in the salary of factory workers based on gender
Always start with a null hypothesis
the null hypothesis (H₀) is a hypothesis which the researcher attempts to disprove, reject or nullify; by attempting to reject the null, researchers can support their experimental hypothesis and draw meaningful conclusions.
The hypothesis that there is no difference between two groups of data, and the experimental observations are due to chance.

Other examples are:

H0: There will be no difference in headache relief between individuals who take Tylenol and those who do not OR Tylenol will have no effect on headache relief.

After the null, list the alternative hypotheses
start with H₁ and then continue listing (H₂,H₃ etc.) as many as are necessary for the experiment
- Examples of alternative hypotheses:
- H₁: Tylenol will allow for relief when consumed by patients with headaches
- H₂: Tylenol will worsen symptoms when consumed by patients with headaches.
Experimental Design
Control:
Negative: Group Not exposed to any treatment Or exposed to a treatment known to have No effect —> Helps ensure there is No effect when there should be no effect.
Positive: Group not exposed to the IV but IS exposed to a treatment known to HAVE an expected effect ——> Ensures the experimental setup can produce a known effect; provides a reference point for what a known effect looks like.

Example: Negative Control

A researcher wants to test the effect of caffeine on heart rate —→
A researcher will give negative control group a treatment that is known to have no effect on heart rate.—→
Water is known to have no effect effect on heart rate with consumption.——>
If water affects heart rate in the negative control group then there must be another variable affect heart rate or the water is contaminated.

Example: Postive Control

A researcher wants to test the effect of a new antibiotic on a strain of bacteria. ——>
How would the researcher Know the new antibiotic (experimental group) is actually-effective?——>
use an established antibiotic that is known to work (positive control group)—→
if the experimental groups fail, but the positive control is successful, it is likely that the tested antibiotics are ineffective.

Variables:

Independent: The one factor that is changed between groups; what is being manipulated graphed on the x-axis

Dependent: Factor that is measured and affected by the IV; graphed on the y-axis.

Constant: factors kept consistent for all groups to ensure only the IV affects the outcome; aka controlled variables.

Note