EOC Practice
Page 10
1. People sweat to help maintain body
temperature. What type of feedback
happens when sweating regulates body
temperature.
c.
Negative feedback because sweating
decreases body temperature.
Note: Homeostasis—in a system feedback
is when one factor causes another to
increase (positive) or decrease
(negative)
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2.
D.
Plants use nitrogen to make
proteins. What is present in the
soil that makes nitrogen directly
available to plants?
Bacteria
Note: basic elements N, O, C are
recylced through an ecosystem. N
from the air is taken by bacteria
where is it available as nitrogen in
the soil (like fertilizer).
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3. How could M and K be more certain
the results of their experiment are
more reliable?
B. Repeat the same experiment in the
same way.
Note: To check reliabilty it is
important that everything tested
remains the same. Repeat the
experiment. If you changed
anything else, you would be testing
something else.
4. Write a conclusion for this controlled
experiment
Question: What is the effect of acidity of
potato juice on the volume of foam
produced when hydrogen peroxide is
added to potato juice?
In your conclusion be sure to
 answer the experimental question (circle)
 Include supporting data from the
table(Sq)
 explain how these data support your
conc.(UL)
 Provide a scientific explanation for the
trend in the data (shade)
answer the experimental question
If you increase the pH of the potato
juice from 6 to 7 then to 8 the
amount of foam produced increases
with each step. However at pH 9 the
amount of foam produced decreases
to less than that of pH 7.
Include supporting data from the table
At pH 6 an average of 24 ml of foam
was produced while pH 7 and pH 8
produced 35 and 42 respectively.
However, at pH 9, the volume of
foam produced dropped to 30 ml.
explain how these data support your
conclusion
The data show that as the pH of the
solution increases from 6,7,8 the
volume of Foam also increases from
24,35,42. However, when the pH is
increased to 9 only 30 ml of foam
were produced.
Provide a scientific explanation for the
trend in the data
The enzyme that releases oxygen
from hydrogen peroxide is helped by
higher pH. However, pH 9 is too high
and this level inhibits the function of
the enzyme.
 At 9, the pH is too high and this level
damages the potato so that enzyme
cannot be released
 A high pH of 9 interacts with the
hydrogen perioxide and prevents the
release of oxygen.

5 What did Mike and Kelsey do to make the
results of their experiment valid?

B. Calculated the average volume of foam
for each acidity.
Note: Validity in an experiment has a
similar meaning to accuracy. If I wanted
to accurately determine how fast you
could run a mile my accuracy would
increase the more times you ran it.
Eventually, an average would be a more
valid measure that if you only ever ran it
once.
What is the effect of the temperature of potato
juice on the time for bubbling to stop after
hydrogen peroxide is added.
Procedure:
1.
Place 10ml of potato juice in 6 test tubes
2.
Set two test tubes aside and place 4 in a
water bath in a 250ml beaker.
3.
Place the water bath on a hot plate and
beginning heating. Place a C
thermometer in the water bath
4.
Label 6 graduated cylinders 2 at 20
degrees 1 at 40 degrees, 1 at 60
degrees. 1 at 80 degrees and 1 at 100
degrees.




5. pour 5ml of H2O2 into a room
temperature potato juice and record how
many seconds bubbles continue to be
formed. Record.
6. when the temperature of the water
bath reaches 40 remove one test tube of
potato juice, add 5ml of H2O2 and record
the time of bubbles.
7. Repeat step six for 60, 80, and 100
degrees.
8. Repeat using the second room
temperature test tube of potato juice.
Controlled variables


1. Controlled for temperature: one
test had no increase in heat.
2. Controlled for time one test tube
had no heat but was tested after the
same amount of time as the longest.
variables


Manipulated (independent):
temperature of potato juice
Responding (dependent): time it
took bubbles to stop.
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7. The green pepper plant has proteins
that control the process of making
glucose. How does the plant obtain
these proteins?
A.
The plant makes the proteins using
the instructions in DNA
8.
Becky and Juan want to increase the
mass of food produced in the school
garden. Which of the following
questions could lead to a possible
solution to this problem?
c. Which plants product the most
protein
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9.
C.
What is the role of cellular
respiration in plants?
To produce ATP
Becky and Juan used a greenhouse
as a model of a garden ecosystem
to predict effects of amount of
sunlight on green pepper
production in a garden ecosystem
Describe two way the greenhouse
model may lead to unreliable
predictions about the effects of
amount of sunlight on green pepper
production in a garden ecosystem.
10.
One way
A greenhouse is kept at a constant
temperature while the outdoor
temperature varies a great deal. The
warm temperature could make the
pepper grow faster.
A greenhouse can be kept at a
constant humidity while it varies
greatly outdoors. A higher constant
humidity could increase pepper
growth faster than outside.

D.
11. What caused the increase in
the average beak size of the finch
population after the 1977 drought?
Finches with bigger beaks were able
to survive and reproduce.
12.
Scientists must be careful that their
activities in an ecosystem do not
introduce any new organisms into
that ecosystem. What might be an
effect on the finch population
Daphne major if a new bid species
were brought to the island.
C. The finch population would decline
due to competition.
13.Before the drought. Daphne Major had
720 finches living on 80 acres of land.
What was the population density of
finches on Daphne Major?
720 ÷ 80= 9 finches per acre
14.Why are the offspring of flowering plants
genetically different from the parent
plants?
A.Sexual reproduction produces offspring
with new combinations of genes
15.What part of the cell produces ATP for
the blueberry plant to grow?
A. Mitochondria
Blueberries contain sugars like glucose.
What is the source of carbon for the glucose
in blueberries?
B. Carbon Dioxide in the air
17.Jose and Tasha want to improve the soil in the
garden by increasing the population of worms in
the soil. Describe how to begin solving this
problem.
Research the problem
a.Under what environmental conditions do worms
grow the best
b.What do worms eat—what diseases do they get
c. Are the different types of worms?

Explore idea
Raise trial populations of worms in different
soils that contain different nutrients. Keep
a record of their numbers.
Visit different gardens and locations—
sample worm poplation and worm size.
Figure out what worms like and need. Try
sample enriched environments.




What is Reliability?
The idea behind reliability is that any significant
results must be more than a one-off finding and be
inherently repeatable.
Other researchers must be able to perform exactly the
same experiment, under the same conditions and generate
the same results. This will reinforce the findings and ensure
that the wider scientific community will accept
the hypothesis.
Without this replication of statistically significant results,
the experiment and research have not fulfilled all of the

Read more: Validity and Reliability - How to Know if the
Research is Correct?