Science
SCI.III.2.4
Grade: 8th
Strand III:
Using Scientific Knowledge in Life Science
Standard 2:
Organization of Living Things - All students will use classification
systems to describe groups of living things, investigate and
explain how living things obtain and use energy; and analyze how
parts of living things are adapted to carry out specific functions.
Benchmark 4: Explain how living things maintain a stable internal environment.
Constructing and Reflecting:
SCI.I.1.1– Ask questions that can be investigated empirically.
SCI.I.1.2– Design and construct scientific investigations.
SCI.II.1.1– Justify plans or explanations on a theoretical or empirical basis.
Vocabulary
Context
Related systems/cells/chemicals:
• Excretory system
• Endocrine system
• Circulatory system
• Nervous system
• Hormones
• Immune response
• White blood cell
• Bacteria
• Virus
• Bacteriophage
• Host cells
Mechanisms for maintaining internal stability:
• Body temperature
• Water levels
• Hormone levels
• Diets
• Disease control
Factors/mechanisms under control:
• Temperature
• Disease/infection
• Homeostasis
• Negative feedback system
• Assimilation
Knowledge and Skills
Resources
An organism’s external environment may be
•
changed by weather, global warming,
earthquakes, floods, etc., but an organism’s
internal environment is stable. An organism’s
stability is maintained by feedback within the
different systems.
Students will:
• Describe how an organism’s internal
environment responds to change
• Explain why an organism’s internal
environment is stable
• Explain homeostasis
Describe the immune system’s response •
to invading organisms.
• Analyze how an internal stable environment
is maintained by feedback within the different •
related systems.
SCoPE Unit – Organisms; Health and
Disease
In this unit students examine how organisms strive to
maintain a stable environment, focusing in
particular on the organisms' response to
attacks by vectors of disease. They examine
the effects and life cycles of organisms that
cause human disease. Students also
describe how technology is used in the
prevention, diagnosis, and treatment of
diseases.
Michigan Teachers Network –
http://mtn.merit.edu/mcf/SCI.III.2.HS.4.html
Homeostasis.
http://www.britannica.com/eb/article?eu=11819
5
•
Homeostasis with feedback loop.
http://bioserve.latrobe.edu.au/vcebiol/cat1/aos2
/u3aos21.html
•
•
•
•
•
•
•
•
•
•
•
Epidemiologists
Endocrinologists
Veterinarians
Family Doctors
Nurses
Lab technicians
Research labs
Colleges and Universities
Videos
Posters
Tours of hospitals or universities
Instruction
•
•
Working in groups, students will maintain a
constant temperature of a beaker filled with
hot water. Using two beakers of water, one
large and one small, a thermometer and cold
water, and a heat source, maintain the large
beaker of water at approximately 90oC.
Describe the process that the group used to
maintain the constant temperature.
Corresponds to standard I.1.5
The teacher will explain the Homeostasis
Feedback Loop Model. Each student will be
given a human homeostatic condition (e.g.,
temperature, sugar level, breathing, etc.).
The student will draw and label a diagram of
a feedback loop for the assigned condition.
Each student will present an oral explanation
of the steps in his or her feedback loop
diagram.
(Rubric available on MI-CLiMB)
Assessment
•
Draw and label a pictorial diagram of a
feedback loop for a given human homeostatic
condition (e.g. temperature, sugar level,
breathing, etc.) Explanation of the steps is
encouraged.
Criteria
Apprent Basic
Meets
Exceeds
Accuracy of
diagram
Draws
and
labels a
diagram
with more
than two
errors.
Draws
and
labels a
diagram
with one
or two
errors.
Draws
and
labels a
diagram
of a feedback loop
that will
function.
Draws and
labels a
diagram
with an
explanation of
each
stage.
Correctness of
order
Connects
the
events
with more
than one
error.
Connects
the
events
with one
error.
Connects
the
events in
a
complete
and
accurate
manner.
Connects
the events
in a
complete
and
accurate
manner
with
additional
information.
Teacher Notes:
Focus Question: What steps must be taken to maintain a stable system?
Investigate and explain how living things obtain and use energy.
The relationship between life and energy is complex. While the generalization that living things need
energy to survive is satisfactory at one level of understanding, it fails to convey the crucial role energy
plays in all aspects of life, from the molecular to the population level. At the elementary level students
can compare and contrast food, energy and environmental needs of selected organisms, such as
beans, corn or aquarium life.
In the middle and high school, the focus is more specific on the concept that plants make and store
food. Scientists speak of the flow of energy through the environment. Almost all life on the earth is
sustained by energy from the sun. This energy is transformed and moved from location to location,
but doesn't disappear. Plants capture the sun's energy and use it to produce energy rich organic
molecules that we call food. The food molecules then serve as energy sources for plants and
ultimately animals.
In animals, organic food molecules are chemically broken down and carried through the circulatory
system to cells, cytoplasm, and eventually to mitochondria. This is, most often the site of final energy
release through the process known as cellular respiration.
The chemical process of photosynthesis occurs at the cellular level and is capable of converting light
energy into molecular energy. Animals are dependent on plants for this first important step in the flow
of energy. In plants, light energy is captured by chloroplasts or chlorophyll and is converted to
chemical energy through the making of organic food molecules when water and carbon dioxide are
chemically combined to make sugar and oxygen. These sugars (organic compounds) formed in
photosynthesis are used for the plant's metabolic processes and maybe ultimately be used as food
for animals. The chemical process of respiration is also cellular. Cellular respiration releases stored
molecular energy so the energy can be used for other life processes. Both plants and animals respire.
The acquisition and use of energy by living things is a very abstract idea for students at all levels.
Students tend to develop a vague and very broad definition of energy that is inconsistent with the
scientific definition. This imprecise definition interferes with the acquisitions of the biological
understanding of energy and its importance in a living system.