Body Works

Activity 14B: Breakdown

October 1, 2014

Activity 14B: BreakdownOctober 1, 2014

Getting Started: Which would dissolve faster, complete uncut rib-eye steak or a rib-eye steak that has been cut into pieces? Explain your reasoning.

Introduction: Read and summarize pg B-19 in one sentence.

Breakdown

You already know the organs in the digestive system. But what exactly do they do? One important function of the digestive system is to break down food into smaller pieces. Only then can the nutrients in the food be absorbed by your body…

Why is it important to chew your food?

14B

Challenge: Rewrite the challenge question in your own words.

Key Words: Chemical Breakdown, control, digestive system, function, mechanical breakdown, organ, qualitative/quantitative data, surface area, variable

Procedure: Have you read and do you understand the procedure part A on pg. B-20? Write one sentence that describes what you will be doing.

Results: The Model

Elements of the digestive processStudent Sheet 14.1 Human Digestive System

Analysis: DiscussionQuestions

Reflection: How can understanding how your liver works help you make decisions about your health?

Elements of the Digestive Process

• How did you decide when the chemical breakdown was over? Did you observe or record how long it took before the tablet piece completely dissolved?

Testing the Model

• What are your observations? What did you see, hear, smell?

• Based on your observations, why your think it is important to chew your food?

Key Words: Chemical Breakdown, control, digestive system, function, mechanical breakdown, organ, qualitative/quantitative data, surface area, variable

Procedure: Have you read and do you understand the procedure part B on pg. B-21? Write one sentence that describes what you will be doing.

Results: Pre-Lab and pre-lab discussion

Conduct ExperimentWork on Bar-GraphStudent Sheet 14.1 Human Digestive SystemCandy Time

Analysis: Complete Conclusion

Experimental Design Elements

Independent and Dependent Variables

Hypothesis

Controlled Variables

Independent and Dependent Variables

• Independent Variables (IV)– IV means “I” control– It’s the part of the experiment you are testing.

• Dependent Variables (DV)– DV depends on the IV– It is the thing you are measuring

Example

• IV - food people eat– Dr. Goldberger decided to test if food was causing

people to get sick so he gave some people fruits and vegetables and others corn, fatback, and syrup.

• DV – whether or not people get pellagra– Dr. Goldberger checked the people to see who got

Pellagra and who did not.

What is the independent variable?

• Asked another way: What are we testing?

What is the dependent variable?

• Asked another way: What are we measuring?

Hypothesis

• Educated guess or prediction• Always stated:– If IV then DV– This means you plug in the independent variable

where it says IV and plug in the dependent variable where it says DV and rewrite your hypothesis.

Example

• Using the Dr. Goldberger example.– IV = different types of food– DV = if they got pellagra

• Write a hypothesis that follows the format:If IV then DV

If different types of food then if they get Pellagra

If people eat food with vitamins then they will not get pellagra.

Controlled Variables or Constant Variables

• Different then control or control group.• These are things that could change every time

you did the experiment if you didn’t control them.– Take Dr. Goldberger’s experiment. • We assume the patients all ate exactly the same diet

maybe they didn’t. • Or if some exercised while others did not.• Or if some were able to shower and wash while others

were not.

These are all things that could effect the experiment so they have to be done exactly the same for each person.

• What are some of the variables we need to keep the same in this experiment? How will we control them?

Pre-Lab Discussion

• Question we are trying to answer– How does the size of your food affect the speed at

which chemical breakdown occurs?

OR

– Does the amount you chew your food affect your ability to digest it chemically?

Candy Time

• Some of you will get a piece of candy that is whole (complete). The rest of you will get candy that has been broken down into smaller parts.

• Time how long it takes you to finish your candy.

• Record what your body was doing on student sheet 14.1 and how that helped in digestion.

Conclusion

• Restate your hypothesis and explain whether it was correct or incorrect. Use data you collected to support your answer.

• Restate the problem statement and answer it using data you have collected.

Amt of vinegar

(mL)

Time to dissolve (sec)

1 2 3 4 5 6 7 Total

0

2.5

5

10

Analysis Question 2

• What part of digestion was modeled by breaking the tablet?

• What part of digestions was modeled by adding the vinegar?

Analysis question 4

• How does the size of your food affect the speed at which chemical breakdown occurs?

Analysis Question 5

• Besides preventing choking, why is it important to chew your food?