Name: _____________________________ Class: __________________ Date: _________________
Human Systems and Homeostasis
Chapter Test B
Answer Key
Multiple Choice
1. c
2. a
3. d
4. d
5. d
6. b
7. c
8. b
9. a
10. a
11. b
12. c
13. d
14. d
15. c
Short Answer
16. Acid is released.
17. The upper loop is a negative feedback loop.
The pH is the set point. Food entering
triggers the release of gastrin, which leads to
the release of more acid, which leads to a
lower pH. Then the loop restores
homeostasis because the lower pH inhibits
the release of gastrin and acid. As a result,
the pH level rises again.
18. the lower pH of the stomach
19. The lower loop shows a positive feedback
loop, because the release of pepsin leads to
the release of more pepsin, moving
conditions away from a set point.
20. A higher pH would stop the production of
pepsin. That would occur after the gastrin
was inhibited. If no more food entered the
system, the gastrin release would stop and
the pH would stay at a higher level.
21. The ship will be driven off course and
damaged by the storm at first. The crew
would have to make adjustments to keep the
ship on course and repair it. A virus can
multiply so quickly that the body cannot
maintain homeostasis at first, but then the
control systems will trigger an immune
response, which will kill the virus.
22. the brain
23. the captain
24. Possible answers: the course toward its
destination, the depth of the water in which
it can sail, the angle of the turn it can make
safely
25. a negative feedback loop
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
1
Human Systems and Homeostasis
Name: _____________________________ Class: __________________ Date: _________________
Human Systems and Homeostasis
Chapter Test B
MULTIPLE CHOICE
Choose the letter of the best answer. (15 credits)
_____ 1. Through the process of
thermoregulation, the body
maintains a stable
a. glucose level.
b. sense of balance.
c. internal temperature.
d. control center.
_____ 3. Why must organ systems
interact as a community?
a. Each organ has to
oversee the functioning
of other organs.
b. Organ tissues are not
specialized, so they work
together.
c. No organ can function
without positive
feedback.
d. Each organ alone cannot
perform all the necessary
tasks.
_____ 2. What do the different
shapes of the cells shown in
Figure 24.1 reflect?
_____ 4. Information from the body’s
sensors goes first to a(n)
a. internal receptor.
b. specific target.
c. impulse hormone.
d. control center.
_____ 5. Which type of tissue lines
the stomach and the lungs?
a. nervous
b. connective
c. muscle
d. epithelial
FIG. 24.1
a. They have different
functions.
b. They lack basic cell
parts.
c. They are becoming stem
cells.
d. They are going through
apoptosis.
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
2
Human Systems and Homeostasis
Name: _____________________________ Class: __________________ Date: _________________
Chapter Test B, continued
_____ 6. Which of the following
statements describes how
you would classify Figure
24.2 as a negative feedback
loop?
_____ 8. What happens to cells
during determination?
a. They become stem cells
and divide into zygotes.
b. They lose the potential to
develop into any type of
cell.
c. They develop specific
structures and organelles.
d. They gain the ability to
build entire organisms.
_____ 9. The development of a
whiplike tail on a sperm cell
during differentiation is the
result of
a. specific genes turning on
and off in a pattern.
b. genetic information
creating whole
organisms.
c. involuntary movements
of muscle.
d. programmed cell death
allowing new growth.
FIG. 24.2
a. The sensors notice an
increase away from a set
point.
b. The control center
counteracts change from
a set point.
c. Nerves and hormones
carry messages to target
organs.
d. A target organ receives
and responds to a
message.
_____ 10. Homeostasis regulates the
internal environment by
a. maintaining conditions
within narrow ranges.
b. speeding up all chemical
reactions.
c. producing a constant
flow of enzymes.
d. altering the ranges that
sustain life.
_____ 7. Which of the following
phrases describes an organ?
a. a collection of interacting
sensors
b. similar cells that function
as one
c. different tissues working
together
d. parts of a communication
system
_____ 11. When cells do not continue
to develop into specialized
cells, they undergo
a. homeostasis.
b. apoptosis.
c. differentiation.
d. determination.
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
3
Human Systems and Homeostasis
Name: _____________________________ Class: __________________ Date: _________________
Chapter Test B, continued
_____ 12. How does a positive
feedback loop respond to
changing conditions?
a. It counteracts a variation
from a set point.
b. It changes a set point to
match current conditions.
c. It increases a change
away from a set point.
d. It reduces any change
that overwhelms a set
point.
_____ 14. Which of the following is
an example of sensors
working during
homeostasis?
a. acidic blood pH
disrupting cell
metabolism
b. blood volume decreasing
from lack of water
c. the pancreas failing to
release insulin
d. energy demands
triggering a release of
glucose
_____ 15. What two organ systems
provide communication in
thermoregulation?
a. circulatory and
integumentary
b. integumentary and
muscular
c. nervous and endocrine
d. respiratory and nervous
_____ 13. When you hold your breath,
sensors in the blood vessels
detect lower oxygen levels.
The brain stem receives the
information and sends
messages through the
nervous and endocrine
systems to the muscles of
the diaphragm, forcing you
to breathe. Which part of
this feedback loop would be
considered the control
center?
a. the endocrine system
b. muscles of the diaphragm
c. oxygen in the blood
d. the brain stem
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
4
Human Systems and Homeostasis
Name: _____________________________ Class: __________________ Date: _________________
Chapter Test B, continued
Short Answer Use the diagram below to answer items 16–20. (5 credits)
Digestion Feedback Loops
FIG. 24.3
16. Digestion of food is a complex process that includes many feedback loops. In
the simplified diagram of digestion that is shown in Figure 24.3, food enters
the stomach, and a hormone called gastrin carries a message to a target. What
happens first when the message reaches its target?
_______________________________________________________________
17. What type of feedback loop is shown in the upper loop? Explain how the loop
does or does not maintain homeostasis.
_______________________________________________________________
_______________________________________________________________
18. The digestive enzyme, pepsin, helps to break down protein in the stomach. In
Figure 24.3, what causes the release of the digestive enzyme pepsin?
_______________________________________________________________
19. How can you tell which type of feedback loop is shown in the lower loop?
_______________________________________________________________
20. What would have to happen to stop the production of pepsin?
_______________________________________________________________
_______________________________________________________________
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
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Human Systems and Homeostasis
Name: _____________________________ Class: __________________ Date: _________________
Chapter Test B, continued
Use the diagram below to answer items 21–25. (5 credits)
FIG. 24.4
21. If a sailing ship represents the human body, how is a sudden storm at sea like a
virus? Use the word homeostasis in your answer.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
22. What is the major control center of the human body?
_______________________________________________________________
23. Who acts as the control center of the ship?
_______________________________________________________________
24. Name a set point that the ship must maintain.
_______________________________________________________________
25. If the wind changes direction, and the ship veers off course, what type of
feedback loop results in the ship returning to its course?
_______________________________________________________________
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
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Human Systems and Homeostasis