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AP Biology

Throughout this course you will study core scientific principles, theories, and processes that govern living organisms and biological systems

The course is broken down into science practices (skills) and content

Go to page 4 of your unit 1 packet

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AP Biology Science Practices

The Science Practices are skills that you are expected to develop and apply throughout the course

The Science Practices include:

Concept explanation
Analyze visual representations
Determine scientific questions and methods
Represent and describe data
Perform statistical tests and data analysis
Develop and justify scientific arguments using evidence

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AP Biology Big Ideas

AP biology content is broken down into four Big Ideas

Big Idea 1: Evolution- the process of evolution drives the diversity and unity of life

Big Idea 2: Energetics- Biological systems use energy and molecular building blocks to grow, reproduce, and maintain dynamic homeostasis.

Big Idea 3: Information storage and transmission- living systems store, retrieve, transmit, and respond to information essential to life processes.

Big Idea 4: Systems interactions- Biological systems interact, and these systems and their interactions exhibit complex properties.

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AP Biology Big Ideas

The Big Ideas serve as the foundation of the course and are further broken down into:

Enduring understandings: long-term takeaways of each concept

Learning objectives: define what a student needs to be able to do with the content knowledge to progress toward the enduring understandings

Essential knowledge: describe the knowledge required to perform the learning objective

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AP Biology Units

This course will cover 8 units:

Unit 1: Chemistry of Life (Big Ideas 2-4)
Unit 2: Cell Structure and Function (Big Ideas 1,2,4)
Unit 3: Cellular Energetics (Big Ideas 2,4)
Unit 4: Cell Communication & Cell Cycle (Big Ideas 2,3)
Unit 5: Heredity (Big Ideas 1,3,4)
Unit 6: Gene Expression and Regulation (Big Idea 3)
Unit 7: Natural Selection (Big Ideas 1,4)
Unit 8 Ecology (Big Ideas 1-4)

Note: Big Ideas in each unit overlap & build on each other

Meaning—what you learn in each unit cannot be forgotten because it is important for other units too!

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Scientific Method

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

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Scientific Method

Observation

Question

Hypothesis

Experiment

Data

Conclusion

Make an

Ask a

Propose a

Design an

Collect

Draw a

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Forming Hypotheses

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

Often heard as: “If … , then … (because…)” but does not need to be in this format

“If”- the manipulated variable
“Then”- the responding variable
“Because” - optional explanation

Results can either support or refute the hypothesis

Do Not SAY, “The hypothesis is correct”

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Hypotheses

Always start with a null hypothesis

Provides a baseline that scientists can test against, helping them determine if their results are significant or due to chance
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

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Hypotheses

Example null hypothesis statements:

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

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Hypotheses

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

Example 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

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Practice problem 1

Determine a suitable null and alternative hypothesis for the question below:

Are teenagers better at geometry than adults?

H₀:

H₁:

Age has no effect on the ability to do geometry

If teenagers and adults are given geometry problems to solve, then adults will solve more problems than teenagers (because they are older and have more experience doing problems)

OR Adults may be able to solve geometry problems better than teenagers

Notice- the “if..then..” format was removed, but it still works as a hypothesis

Once the hypothesis is developed, observation is a key part of the scientific method.

Observe this lit object and write down details that you observe.

Contrast direct observation vs. inference. clip

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Practice or HW

Work on practice problems 2-4 on page 7 of your notes packet.

See Mr. Conrad with questions.

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Experimental Design

Groups

Control

Experimental

Negative

Positive

Variables

Independent

Dependent

Constant

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Experimental Design

Used for comparison to the experimental group; help to validate statistical analysis and increase confidence in conclusions drawn from the experimental results

Receives the experimental treatment (IV) being tested to observe its impact on the outcome (DV)

Groups

Control

Experimental

At least 3 trials needed per group

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Experimental Design

Group NOT exposed to any treatment OR exposed to a treatment known to have NO effect

Group not exposed to the IV but IS exposed to a treatment known to HAVE an expected effect

Control

Negative

Positive

Helps to ensure there is NO effect when there should be NO effect

Ensures the experimental setup can produce a known effect; provides a reference point for what a known effect looks like

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Example Negative Control

A researcher wants to test the effect of caffeine on heart rate

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 on heart rate with consumption

If the water affects heart rate in the negative control group then there must be another variable affecting heart rate or the water is contaminated

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Example Positive 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.

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Experimental Design

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

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

Variables

Independent

Dependent

Constant

Factors kept consistent for all groups to ensure only the IV affects the outcome; aka controlled variables

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Think, Pair, Share

Why is it important to ONLY change the independent variable?

To ensure that any observed changes in the DV are directly caused by the manipulation of the IV

What is a bias? How can a bias affect an experiment?

A bias is a prejudice in favor of or against something. Many researchers are trying to prove something by their experiments, and that in itself is a bias. This can affect an experiment because researchers can interpret or design an experiment around their bias. This is why there are blind, and even double-blind studies to help eliminate bias in experiments.

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Concept Check

Read the problem below and identify the independent and dependent variables:

You are washing cars to earn money. For each car you wash, you earn $10.

Independent variable: the amount of cars you wash
Dependent variable: the amount of money you receive

The amount of money you receive DEPENDS on the number of cars you wash

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Practice

Read the problem below and identify the independent and dependent variables:

You are interested in how stress affects heart rate in humans. You place humans under different levels of physical stress and measure their heart rate

Independent variable: physical stress exposure
Dependent variable: heart rates

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Practice

Work on practice problems 3-5 packet p. 10

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Practice

You want to design an experiment to determine if a new drug has an impact on lowering blood pressure. Test subjects with high blood pressure are given a new medication in pill form. The percentage of patients whose blood pressure decreased is measured. What are good positive and negative controls?

Negative control: placebo pill (or substance that has no effect)
Positive control: Test subjects are given a drug that is known to reduce blood pressure.

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Practice

You believe that when someone drinks a soda, their heart rate will increase. You set up an experiment, using various sodas, and various amounts of consumption and then measure the heart rate of the individuals. What are good positive and negative controls?

Negative control: water
Positive control: energy drink

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Practice

Work on practice problems 3-4 p. 11