UNIT 5: Structure and Function of Organisms, Part 2
Page 198
Using the materials provided by
your teacher, design a filter to model how
kidneys filter waste from the blood. The “blood”
to be cleaned is muddy water.
In your science notebook, draw
and label the filter and describe the efficiency of
the filter.
Keep a small amount of muddy water to use as a control for comparisons.
Participate in a gallery walk to observe
filters created by
other groups. S
e 100
Sheets 200 Pages Wide Ruled
9 3/4 x 7 1/2 in. 24.7 x 19.0 cm
1. Compare the water before and after filtering through each one of the filters.
Which one cleaned the water most efficiently? Student answers will vary.
Accept all appropriate answers.
2. Which of the filters is most like the kidneys?
Why? Student answers will
Accept all appropriate answers
The function of the kidneys is much more complex than your model. There is a
delicate chemical balance that must be maintained in the body. The kidneys are
in that they measure amounts of chemicals your body needs, such
as sodium, phosphorus, and potassium, and they make sure there is the correct
amount in the blood for your body to function.
Facilitation Questions
What was the shape and structure of the most effective filter? Answers will
vary, but a funnel shape that has several layers of filter paper is likely the most
The kidney is the main organ of the excretory system.
How are the filtering units,
called nephrons, like the filtering models made by
you? Both filter the “blood”
How are they different? The nephrons filter wastes out of the blood, while our
models filtered the dirt materials out of the water.
Lesson 1: Physical and Chemical Changes in Digestion
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