Topic 2- Homeostasis in Organisms
As a collection of organized biological
systems, a living thing must keep all of its
biological systems stable. To maintain this
internal stability, called
____________________, an organism must
continually monitor and respond to changes
in the environment.
Basic Biochemical Processes
Biochemical processes are the
_________________ processes that occur
within an organism.
Since all organisms need both
___________ and ____________ for their
biochemical processes to occur, two of the
most important processes involve storing
energy in matter and retrieving that energy as
needed. These processes are called
____________________ and
___________________.
The process of storing solar energy as chemical bond energy in organic
molecules, such as ____________________, is called _______________________.
Photosynthetic organisms include:
 ________________
 ________________
 many ____________________ organisms
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Photosynthesis
The energy for life comes primarily from the ___________. However, solar
energy can’t be directly used by living things. Photosynthesis ______________
solar energy into _________________ bond energy, which living things can use.
Photosynthesis requires specialized ____________ molecules to capture
and convert the solar energy. In plants, these green pigment molecules are called
___________________ and stored in oval-shaped organelles called
_____________________.
One of the most common energy-rich organic molecules produced by
photosynthesis is the sugar ____________________. It’s made by combining two
inorganic compounds, _________________________ (CO2) and ____________
(H2O).
Fortunately for us, photosynthesis also produces a valuable ______________
product, __________________.
In sentence form, the reaction of photosynthesis would read:
Six molecules of ________________________ react with 6 molecules of
__________________, in the presence of ___________________, to produce
_____________________ and 6 molecules of ________________.
Written as a chemical equation, photosynthesis is:
_____________
6______ + 6______ _____________ + 6______
The simple sugars produced by photosynthesis can be used in two ways:
 as a source of _____________ for the organism, or
 as a building block of other ________________________like ___________
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Photosynthesis Review
Name_____________________________
1. What is the relationship between pigments and chlorophyll?
2. Write the basic equation for photosynthesis using the names of the starting and final
substances of the process.
3. What role do plant pigments play in the process of photosynthesis?
4.
Identify the structures labeled A, B, C, and D. In which
structure(s) do the light-dependent reactions occur?
5. In which structure(s) does the Calvin cycle take place?
6. Explain the role of NADP+ as an energy carrier in photosynthesis.
7.
In which part of photosynthesis is oxygen produced?
8.
Summarize what happens during the Calvin cycle.
9. How do the events in the Calvin cycle depend on the light-dependent reactions?
10. Describe three factors that affect the rate at which photosynthesis occurs.
Matching Match each term with its description below. Write the letter of the correct term on the line
provided.
a. chlorophyll
d. photosynthesis
b. stroma
e. light-dependent reactions
c. pigment
11. ______________ molecule that absorbs certain wavelengths of light
12.______________ produce oxygen gas and convert ADP to ATP
13. ______________the region outside the thylakoid membranes
15.______________ principal pigment found in plants
16.______________ process by which autotrophs use sunlight to make high-energy sugars
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On the lines provided, write the names of the
reactants and products for photosynthesis that
correspond to the numbers in the diagram.
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17
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17._____________________
18._____________________
19._____________________
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20. _____________________
21. _____________________
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Respiration
The process of breaking down the simple organic molecules made by photosynthesis to
release the stored energy is called _______________________.
______________ organisms carry out this important process.
The energy contained in organic molecules is too much for any organelle to safely
use. Instead, this energy is used to create smaller molecules called ATP (Adenosine
triphosphate). By using ATP like a _________________ battery, an organelle can get just
the amount of energy it needs to carry out its function.
Respiration is basically photosynthesis in reverse. In sentence form,
6 molecules of _____________ react with one molecule of ________________ to
produce energy (in the form of __________), 6 molecules of _____________________
and 6 molecules of ____________________.
Notice that the solar energy used in photosynthesis to make glucose is released as
chemical bond energy in ATP.
Written as a chemical equation, respiration is:
6 ___ + ______________  36 ATP + 6 ______ + 6 _______
Once complex carbohydrates (like _______________) have been broken down
into simpler molecules (like ______________) by digestion, the process still isn’t
complete. The energy-rich molecules are now small enough to travel to all cells of the
body. However, the energy captured in the molecules by photosynthesis is still trapped
as chemical bond energy.
To get the energy back out, the molecules must pass through a series of chemical
reactions controlled by special proteins (_________________). The series of chemical
reactions are called ___________________________________.
There are two types of cellular respiration:
1) Aerobic Respiration
Uses _________________
Releases the most energy (as _________)
Produces ________ and __________ as waste
2) Anaerobic Respiration
Doesn’t need __________________
Releases very little energy
Produces _____________________ as waste (builds up in cells)
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The energy released through respiration is used to attach a single phosphate
group (P) to a molecule of Adenosine Diphosphate (ADP). In this way, the energy
released from simple molecules is stored in amounts much smaller and safer for the cell
organelles to use. This new molecule that the cells use for their energy is called
Adenosine Triphosphate (__________).
ADP
+
ATP
P
In organisms with membrane-bound organelles (like a nucleus, golgi, ER, etc), the
_____________________ is the site where respiration occurs. As you can probably
imagine, cells that are very active would require a lot of energy. Any cell that requires a
lot of energy would need to have many mitochondria in it. What type of tissue would be
made of cells with lots of mitochondria inside? (Hint: It moves a lot.)
___________________
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Synthesis
Another important biochemical process involves making complex organic molecules
from simple ones. This is called ______________________.
_____________________ is commonly used as a building block for making larger
molecules to store __________ energy. The molecules can be simply connected to form
long chains of simple sugars, or rearranged for long-term storage.
_________________- Long chains of simple sugars
_________________- Food reserve (long-term)
Synthesis is also used to build __________________ and nucleic acid.
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Organic compounds
Small
diagram
Large
diagram
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Enzymes
A _________________ is any substance that can affect the rate of a chemical
reaction without ever getting used up. Enzymes are protein catalysts.
Examples of Biochemical Reactions Requiring Enzymes
 ________________________
 ________________________
 ________________________
 ________________________
Enzyme activity is critically dependent on shape. Just like a lock must have a
certain-shaped key to work properly, an enzyme’s shape must match the compound
they’re meant to work on. Any enzyme whose shape is altered will no longer work.
Factors That can Alter an Enzyme’s Ability to Work)
1) _______________________
Enzymes can lose their ______________ when exposed to high
temperatures or acids and bases.
2) _______________________
High ______________________ cause more collisions
between molecules
3) _____________
Enzymes which work in different places will be adapted to
work best at the pH normally found in that place. An enzyme
which works well in the acidic environment of the stomach
wouldn’t work as well in the basic environment of the small
intestine.
4.
Concentration
The rate of reaction is dependent on the concentration of both the
substrate, and the enzyme
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Hydrolysis
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Homeostasis
Using __________________ as an example, you can see why maintaining a
___________ internal environment is so important for living things. If things are too far
out of whack (so to speak), bad things start happening. Warm weather can help you to
do things, but a high fever can cause an __________________ to lose its shape and stop
working.
Since your internal and ___________ environment are continually changing, your
body has to monitor these changes continually and make adjustments as needed.
Maintaining a stable ____________ environment is called __________________ and the
way living things monitor the changes and respond is called _____________________.
Examples:
Try as we may, it’s nearly impossible to maintain a perfectly stable internal
condition. Things are always changing. For this reason, the best we can hope to achieve
is a “_________________________________________”. When something changes, our
bodies take corrective action to reverse the change. When the change becomes too
great, we reverse the action. In the form of a graph, this process would look something
like these examples:
Body Temperature and Dynamic Equilibrium
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Blood Glucose Level and Dynamic Equilibrium
Feedback Mechanisms
The way an organism’s systems detect, and respond to, changes to restore
homeostasis is called a feedback mechanism. These mechanisms can either increase the
change (___________________ feedback) or squash the change
(__________________________ feedback).
Positive Feedback
When a pregnant woman feels a “need” to push during childbirth, this is a
result of a positive feedback system. As the baby pushes against the base of
the uterus, the mother’s body feels a greater need to contract the muscles
around the uterus. The baby gets squeezed harder against the base, the
contractions get stronger, etc, until the baby is born.
Negative Feedback
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This is the most common type of feedback mechanism, designed to
____________things from getting out of control. Below are a couple of
examples in humans and one from your house!
HOME
HUMAN
HUMAN
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Disruptions of Homeostasis (Disease)
Pathogens
Disease-causing organisms (See below)
Common Pathogens:
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Cancer
Some cells may lose the ability to control how quickly they grow or
how they develop. The result is often a mass of defective cells called
a ________________.
Fortunately, most cancerous cells are recognized as “foreign”
because of abnormal proteins in their cell membranes. The body’s
immune system then attempts to destroy them. Most of the time it
works. Sometimes it doesn’t.
The Immune System
When our other defenses don’t work and we become invaded by pathogens or
our cells stop working correctly, our immune system swings into action.
Pathogens, foreign substances, or cancer cells can be identified by proteins
embedded in their surfaces or cell membranes called ______________________.
When foreign (“not self”) antigens are detected, the immune system creates
__________________________ to engulf and destroy the attacker and/or antibodies to
attack or flag them for attack by more white blood cells. Kind of like “popping smoke”
over an enemy’s position, showing attack planes where to attack.
Nice thing, your immune system “learns”. Once an effective antibody’s been
made, some of the white blood cells that made it stick around. Just waiting for the day
when the pathogen may return. That way, they can start making the right kind of
antibody again, right away this time.
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Vaccinations
Remember that your immune system can “learn”? Well, it can also be “taught”.
Antigens on the surface of live pathogens can also be found on __________ or
_______________________ ones, as well.
Doctors have found that they can teach the immune system how to prepare for
future attack by injecting dead or weak versions of pathogens into the body. The
immune system swings into action. White blood cells start making
_____________________ until they make them with the right shape. Sometimes, these
white blood cells remain for good. Other times, the body requires a “booster” as a
reminder.
Damage to the Immune System
Factors which can weaken the immune system:
 _______________
 _______________
 _______________
 _______________
Unwanted Immune Responses
___________________
Rapid, excessive immune response
Production of histamines to produce:
-mucus
-sneezing
-itching
-rash
-swelling
Inability to recognize “_____________” cells
Attacks on _____________________ organs
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Disease Research
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Worksheet








Photosynthesis
Name___________________
The light reactions can only take place in the ____________________________
Dark reactions also called the Calvin Cycle take place ______________________
The reactants in the light reactions are _______________________________
The reactants in the dark reactions are ________________________________
The product in the light reactions is ________________________________
The product in the dark reaction is ____________________________________
If light intensity increases the rate of photosynthesis _______________________
If the light intensity decreases the rate of photosynthesis _____________________
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 Chloroplast contain several types of ____________________________.
 Chlorophyll is a _____________________ or color.
 When light shines on a pigment, it absorbs all of the _______________ except for
the one you see.
 Leaves look green because _________________ light is not absorbed.
 Red light has the most ________________________
 Purple light has the least ________________________
 Chlorophyll a and b are the 2 primary ____________________.
 Paper chromatography is a method of ___________________ the types of
chlorophyll in a leaf
 A green plant placed in green light will not perform
_________________________.
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Topic 2 Test review (Homeostasis)
1. Vaccines immunize the human body by stimulating the
(1) poisoning of viruses
(3) formation of toxins
(2) ingestion of bacteria
(4) formation of antibodies
2. In which process do some organisms use carbon dioxide and produce oxygen?
(1) circulation
(3) digestion
(2) respiration
(4) photosynthesis
3. Which phrase best describes cellular respiration, a process that occurs
continuously in the cells of organisms?
(1) removal of oxygen from the cells of an organism
(2) conversion of light energy into the chemical bond energy of organic molecules
(3) transport of materials within cells and throughout the bodies of multicellular
organisms
(4) changing of stored chemical energy in food molecules to a form usable by organisms
4. The diagram shows the interaction between blood sugar levels and pancreatic activity.
This process is an example of
(1) a feedback mechanism maintaining homeostasis
(2) an immune system responding to prevent disease
(3) the digestion of sugar by insulin
(4) the hormonal regulation of gamete production
5. Which phrase best describes cellular respiration, a process that occurs
continuously in the cells of organisms?
(1) removal of oxygen from the cells of an organism
(2) conversion of light energy into the chemical bond energy of organic molecules
(3) transport of materials within cells and throughout the bodies of multicellular
organisms
(4) changing of stored chemical energy in food molecules to a form usable by organisms
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6. Blood proteins that protect against disease are known as
(1) toxins
(3) antibiotics
(2) amino acids
(4) antibodies
7. The effect of temperature on the relative rate of action of an enzymeis represented
in the graph below.
The optimum (best) temperature for the action of this enzyme is approximately
(1) 15°C
(3) 37°C
(2) 22°C
(4) 50°C
8. Which activity would not be carried out by an organism in order to maintain a stable
internal environment?
(1) removal of metabolic waste products
(3) production of offspring
(2) transport of organic food molecules
(4) regulation of life processes
9. Which word equation represents the process of photosynthesis?
(1) glucose  alcohol + carbon dioxide
(2) carbon dioxide + water  glucose + oxygen
(3) chlorophyll + water  glucose + alcohol
(4) glucose + oxygen  carbon dioxide + water
10. The process during which energy is released from digested foods is called
(1) cellular respiration
(3) photosynthesis
(2) chemical digestion
(4) excretion
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11. Which equation illustrates a process of nutrition carried out within the leaf above?
(1) B + C  A + D
(3) B + D A + C
(2) A + C  A + B + C
(4) A + B + D  B + C
12. The process represented in this diagram is
(1) respiration
(3) photosynthesis
(2) coordination
(4) immunity
13. What term would most appropriately be represented by the
"X"?
(1) ATP
(3) antibodies
(2) chlorophyll
(4) glucose
14. What is present within the mitochondrion that allows the reaction to occur?
(1) enzymes
(3) bacteria
(2) chlorophyll
(4) carbon dioxide
15. Uncontrolled cell division is known as
(1) meiosis
(2) cancer
(3) antibody production
(4) sexual reproduction
Lyme Disease
Since 1980, the number of reported cases of Lyme disease in New York State has
been increasing. The carrier of Lyme disease is the black-legged tick, Ixodes scapularis.
The disease is spread from infected animals to ticks that bite these animals. Humans
bitten by these ticks may then become infected.
The symptoms of Lyme disease do not always occur immediately after a tick bite.
An individual may develop a skin rash several days to weeks after being bitten by a tick.
Flu-like symptoms, such as headaches, muscle aches, joint pain, and fever, may also
develop. Generally, these symptoms clear up even if the individual does not
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seek medical help. In some cases, there may be no symptoms other than a sudden onset
of arthritis. However, in a small number of cases, if the infection is not treated, it may
lead to chronic arthritis, disorders of the heart and nervous system, or in a few cases,
death. A blood test can help to confirm a diagnosis, and
antibiotics are effective in treating the infection.
People may take preventive action by frequently checking themselves and their
pets for ticks, tucking their pant legs into socks when walking through woods or high
grass, wearing light-colored clothing to aid in spotting a tick, and using insect repellent.
16. Describe how Lyme disease is spread.
17. State one way people might protect themselves from Lyme disease.
18 & 19 State two symptoms that may occur if a person has Lyme disease.
20. State one danger of ignoring any symptoms that may develop after a tick bite.
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Enzyme Review Sheet
______________________
Name
1. The diagram below illustrates a biochemical
process that occurs in organisms.
The substance labeled “catalyst” is also known as
(1) a hormone (3) an antibody
(2) an enzyme (4) an inorganic compound
An investigation was performed to
determine the effects of enzyme X on
three different disaccharides (double
sugars) at 37°C. Three test tubes were
set up as shown in the diagram below.
At the end of 5 minutes, the solution in each test tube was tested for the presence of
disaccharides (double sugars)
and monosaccharides (simple
sugars). The results of these
tests are shown in the table
below.
2. What can be concluded about the activity of enzyme X from the data table?
__________________________________________________________________
_____
__________________________________________________________________
_____
3. A characteristic of hormones and enzymes that allows them to work effectively with
other organic molecules is their (1) specific shape (2) small size (3) concentration of
carbon and hydrogen atoms
(4) high-energy bonds
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4. The effect of pH on a certain enzyme is shown in the
graph below.
At what pH would the enzyme be most effective?
(1) above 10 (2) between 5 and 7
(3) between 8 and 10 (4) below 5
Base your answers to
questions 5 through 7 on the
diagram below that represents
a human enzyme and four
types of molecules present in
a solution in a flask.
5. Which molecule would most likely react with the enzyme?
____________________
6. Explain your answer to question 5.
_______________________________________
__________________________________________________________________
_____
7. State what would most likely happen to the rate of reaction if the temperature of the
solution in the flask were increased gradually from 10°C to 30°C.
__________________________________________________________________
____
8. A colony of bacteria growing on a culture medium is successfully synthesizing an
organic compound. Which procedure would be least likely to have an effect on this
synthesis?
(1) adding more subunits of the organic compound to the medium
(2) lowering the pH of the medium
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(3) raising the temperature of the colony from 20°C to 30°C
(4) increasing the number of hormone molecules in the colony
9.
An enzyme and four different molecules are shown in the diagram below.
The enzyme would most likely affect
reactions involving
(1) molecule A, only (2) molecule C, only
(3) molecules B and D (4) molecules A
and C
Use the diagram on the next page and your
knowledge of biology to assist you in answering
questions 10 and 11 which follow.
10. Pepsin works best in which type of
environment?
(1) acidic, only (2) basic, only (3) neutral
(4) sometimes acidic, sometimes basic
11. Neither enzyme works at a pH of (1) 1 (2) 5 (3) 3 (4) 13
The diagram below represents a beaker containing a solution
of various molecules involved
in digestion.
12. Which structures represent products of digestion?
(1) A and D (2) B and E (3) B and C (4) D and E
13. An incomplete graph is shown below.
What label could appropriately be used to replace letter Z
on the axis?
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__________________________________________________________________
14. Enzymes have an optimum
temperature at which they
work best. Temperatures
above and below this optimum
will decrease enzyme activity.
Which graph best illustrates
the effect of temperature on enzyme activity?
15-17. Enzyme molecules are affected by changes in conditions within organisms. Explain
how a prolonged, excessively high body temperature during an illness could be fatal to
humans. Your answer must include:
• the role of enzymes in a human
• the effect of this high body temperature on enzyme activity
• the reason this high body temperature can result in death
18. Define the term denatured.
19. Define the term active site.
20. Define the term substrate.
21-24. Correctly complete the following chart.
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