Answers to Formative Assessment 28.2

1. +
Formative Assessment
28.2

2. +
1. A system to maintain
homeostasis must have at least 4
parts that function together. Name
these and parts and briefly explain
what each one does.
 Senors – gather information
 Control centers – analyze & compares the information to the
desired values
 Communication systems – send messages from the control
center to regulate the change
 Targets – receive & respond to the messages

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2. What is the main difference
between the way negative feedback
and positive feedback mechanisms
regulate changes in the body?
 Negative feedback loops counteract change to return to a set
point.
 Positive feedback loops accelerate change away from a set
point

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3. When a newborn baby nurses,
the mother’s body is stimulated to
produce milk. What would happen
to the mil supply if the mother chose
to bottle feed rather than breast
feed? Why?
 Nursing a baby creates a positive feedback loop causing the
mother’s body to lactate. Bottle feeding eliminates the stimulus.

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4. Suppose you go on a long hike in
hot weather. Describe a possible
negative feedback loop that would
keep your body from overheating.
 Sensors detect rise in body temperature
 Increase in blood flow to skin (vasodilation)
 Sweat glands activated to cause sweating
 Increase in heart & breathing rates

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5. Reptiles regulate their body
temperature by changing their
environment. A snake, for instance, must
lie in sunlight to warm its body.
Mammals, on the other hand, can
regulate their internal environment to
gain or lose heat. How might this ability
give mammals an advantage over
reptiles?
 Mammals can live in a wider range of habitats & tolerate rapid
changes in external conditions