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Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
www.keepitsimplescience.com.au
Page 1
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KISS Resources for the NSW Syllabus.
KEEP IT SIMPLE SCIENCE
PhotoMaster Format
®
keep it simple science
Maintaining a Balance
Senior Science Subject
Topic Bio 9.2
Biology HSC Course Topic 1
NSW Syllabus Content reference
Maintaining
a Balance
Topic Outline
4. Excretion
& Water
Balance
1. Enzymes &
Homeostasis
Kidney Structure
& Function
Water Balance in
Insects, Mammals
& Plants
Functions & Characteristics
of Enzymes
Factors which affect
enzyme activity
Concept of
Negative Feedback
2. Temperature
Regulation
INSPECTION COPY
for schools only
Hypothalamus & Temperature
Effector Organs Range of Life
Temperature Regulation in
Ectotherms, Endotherms & Plants
3. Internal
Transport
Blood & Blood Vessels
Substances Transported
Transport in Plants
What is this topic about?
To keep it as simple as possible, (K.I.S.S. Principle) this topic covers:
1. ENZYMES & HOMEOSTASIS
What are enzymes? Functions & characteristics. Factors that affect enzyme
activity... temperature, pH & substrate concentration.
Negative feedback control systems. What is Homeostasis?
2. TEMPERATURE REGULATION IN LIVING THINGS
The hypothalamus & effector organs in mammals.
Temperature regulation in endotherms, exotherms & plants.
3. INTERNAL TRANSPORT SYSTEMS
Blood & blood vessels. What the blood carries. Gas transport.
Transport in plants... xylem & phloem.
4. EXCRETION & WATER BALANCE
Importance of water for homeostasis.
Kidney & nephron structure & function. Water balance in insects &
mammals. Water conservation in plants.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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KISS Resources for the NSW Syllabus.
1. Enzymes & Homeostasis
®
keep it simple science
Metabolism is Chemistry
The Importance of Shape
Everything that happens inside a living thing is
really a matter of cell chemistry... “metabolism”.
For example...
Many of the properties of enzymes are related to
their precise 3-dimensional shape.
The shape of the enzyme fits the “substrate”
molecule(s) as closely as a key fits a lock.
• For your body to grow, cells must divide and add
more membranes, cytoplasm and organelles. This
involves the chemical construction of new DNA
molecules, new phospholipids for membranes and
so on.
Various
Only this
one fits
Enzyme
molecule
• All these chemical reactions require energy.
Energy is delivered by the ATP molecule, itself the
product of a series of chemical reactions in the
mitochondria... cellular respiration.
Different
Substrate
Molecules
All of these reactions are “metabolism”: the sum
total of all the thousands of chemical reactions
going on constantly in all the billions of cells in
your body.
This is why enzymes are “substrate-specific”...
only one particular enzyme can fit each substrate
molecule. Each chemical reaction requires a
different enzyme.
Enzymes
Changes in temperature and pH (acidity) can cause
the shape of the enzyme to change. If it changes its
shape even slightly, it might not fit the substrate
properly any more, so the reaction cannot run as
quickly and efficiently. This is why enzymes are
found to work best at particular “optimum”
temperature and pH values.
Every reaction requires a catalyst... a chemical
which speeds the reaction up and makes it happen,
without being changed in the process.
In living cells there is a catalyst for every different
reaction. Biological catalysts are called enzymes.
Enzymes are protein molecules.
Substrate...
Each has a particular 3-dimensional shape, which
fits its “substrate” perfectly.
Enzymes are highly “specific”. This means
that each enzyme will only catalyse one
particular reaction, and no other.
Enzyme shape
at optimum pH
and
temperature
Enzymes only work effectively in a relatively
narrow range of temperature and pH (acidity).
INSPECTION COPY
for schools only
...no longer
fits enzyme
From Amino Acids to Enzyme, to Metabolic Control
Amino acid molecules
Protein, with precise 3-D shape...
Polypeptide chain
Polymerisation
Enzyme’s
“Active Site”
has a shape
to fit the
substrate(s)
exactly
Shape changes
slightly at
different pH or
temp.
...becomes
an ENZYME
molecule
Twists
& folds
Substrate
molecules are chemically
attracted to
the enzyme’s
active site
ENZYME
Biology 9.2 “Maintaining a Balance” PhotoMaster
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Substrate molecules
brought together and
react with each other
ENZYME
Page 3
Product
released from
enzyme
ENZYME can react
with more substrate
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The pH Scale
®
The acidity or alkalinity of any solution is measured on
a numerical scale known as “pH”.
keep it simple science
increasing
acidity
On the pH scale, anything which is neutral
(neither acid nor alkaline) has a pH = 7.
3
4
6
5
increasing
alkalinity
Neutral
7
8
9
10
11
The inside environment of a cell, and most parts of an organism’s body, is always very close to pH 7...
i.e. neutral. An exception is in the stomach where conditions are strongly acidic. (approx. pH 2)
Enzyme Activity Graphs
You will have done experimental work to measure the “activity” of an enzyme under different conditions of
temperature, pH and the concentration of the substrate chemical.
You may have measured the rate of a chemical
reaction being catalysed by an enzyme, such as:
• the rate of milk clotting by junket tablets.
• the rate of digestion of some starch by amylase
• the rate of decomposition of hydrogen
peroxide by “catalase” enzyme.
A common way to measure the rate of a reaction is
to measure the time taken for a reaction to reach
completion... the shorter the time taken, the faster
the reaction. This why the reciprocal of time taken
(1/time) is used as the measure of rate of reaction.
The Effect of Temperature
When enzyme activity is measured at different temperatures, the results produce a graph as below.
1/time taken for reaction (rate)
Explanations
Experimental
Points
As temperature rises the rate increases because the
molecules move faster and are more likely to collide and
react. All chemical reactions show this response.
However, beyond a certain “optimum” temperature, the
enzyme’s 3-D shape begins to change. The substrate no
longer fits the active site so well, and the reaction slows. If
the temperature was lowered again, the enzyme shape, and
reaction rate could be restored.
INSPECTION COPY
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If the temperature reaches an extreme level, the distortion of
the enzyme’s shape may result in total shut-down of the
reaction. The enzyme may be permanently distorted out of
shape, and its activity cannot be restored. We say the enzyme
has been “denatured”.
Temperature
Optimum Temperature
Not all enzymes will “peak” at the same temperature, or have
exactly the same shape graph. In mammals, most enzymes
will peak at around the animal’s normal body temperature,
and often work only within a narrow range of temperatures.
An enzyme from a plant may show a much broader graph,
indicating that it will work, at least partly, at a wider range of
temperatures.
An enzyme from a thermophilic bacteria from a hot volcanic
spring will show a totally different “peak” temperature,
indicating that its metabolism will perform most efficiently at
temperatures that would kill other organisms.
Biology 9.2 “Maintaining a Balance” PhotoMaster
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Page 4
Reaction Rate
Mammal
Enzyme
Plant
Enzyme
0
Thermophilic
bacteria
enzyme
20
40
60
80
o
Temperature ( C)
100
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The Effect of pH
keep it simple science
When the temperature is kept constant
and the enzyme tested at various pH
levels, the results will produce a graph as
shown.
The digestive enzyme “pepsin” from the stomach shows an
optimum pH about 2 or 3, allowing it to work best in the
acidic environment.
Intra-cellular
enzyme
1/time (rate) Enzyme Activity
The shape of the pH
graph is usually
symmetrical on
either side of the
“peak”.
Pepsin.
(Stomach
enzyme)
Enzyme Activity
®
The explanation for
the shape is as follows:
2
3
4
5
6
pH
7
8
9 10
Generally, all intra-cellular enzymes (i.e.
those from within a cell) will show peak
activity at about pH = 7, very close to
neutrality.
1
2
3
4
5
6
pH
7
8
9 10
11
• at the optimum pH the enzyme’s 3-D shape is ideal for the
substrate, so reaction rate is maximum.
• at any pH higher or lower than optimum, the enzyme’s
shape begins to change. The substrate no longer fits, so
activity is less.
• at extremes of pH, the enzyme can be denatured and shows
no activity at all.
Effect of Substrate Concentration
Generally in any chemical reaction occurring in solution the
rate of the reaction increases if the concentration of the
reacting chemical(s) is increased. The explanation is simply
that if the molecules are more concentrated, then it becomes
more likely that they will collide and react with each other.
When an enzyme is involved, the situation is a little more
complicated:
If, at this point, you were to add more
enzyme then the reaction rate would once
again go up. It would level off again as
the enzyme molecules were once again
swamped and saturated with the
substrate.
Initially the rate of the reaction increases as the substrate
concentration goes up, just as it does with any reaction.
Soon though, the graph begins to flatten out and level off
because the enzyme molecules are “saturated” with
substrate and cannot work any faster.
Reaction Rate
Reaction Rate
Levels out
Extra enzyme
added
Initial Increase
in Rate
INSPECTION COPY
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Substrate Concentration
Substrate Concentration
Biology 9.2 “Maintaining a Balance” PhotoMaster
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Page 5
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
Homeostasis
®
keep it simple science
Metabolism is largely a matter of chemical reactions, and each
reaction is catalysed by an enzyme. Enzymes are very sensitive to temperature and pH.
Therefore, it follows that an organism’s
body and cells must be maintained at
stable temperature and pH levels close to
the optimum for the enzymes.
The process of maintaining a stable,
internal environment is called
“Homeostasis”.
As well as regulation of temperature and
pH, homeostasis involves the regulation of
many other factors such as:
• water and salt balance in body fluids.
• blood sugar levels.
INSPECTION COPY
for schools only
• oxygen and carbon dioxide levels.
Feedback Mechanisms
A “feedback mechanism” is a situation where the result of some action
feeds back into the system to control the next change to the system.
In a “Positive Feedback” system any change
re-reinforces itself by causing more change in
the same direction.
In “Negative Feedback” any change causes the
next change to be in the opposite direction.
A good example is an oven thermostat control:
Heat ignites
more fuel
Turn heater
OFF
O
It never results in
stability.
If temperature
is too high
nh
s
Positive Feedback
always causes a
system to grow
out of control, or
shrink away to
nothing.
ol
Fire grows
larger
co
Heat ignites
more fuel
n
Fire grows
larger
NEGATIVE FEEDBACK ACTION
ve
Produces
more heat
Turn heater
ON
NEGATIVE FEEDBACK ACTION
produces
heat
eat
su
p
small fire
Ove
For example, a fire growing bigger...
Temperature
Sensor
(detector)
Negative Feedback
causes a system to
maintain stability.
If temperature
is too low
The result is that the temperature of the oven
remains fairly stable. It oscillates up and down
a little, but always stays close to the
temperature the oven was set at.
Homeostasis is always “Negative Feedback” control.
This ensures that stable conditions are maintained so that enzymes are operating near optimum.
In animals, it is the Nervous System which is
The key parts of a negative feedback system are:
largely responsible for carrying out the receptor
and control centre functions necessary for many
• a receptor, to measure the conditions.
aspects of homeostasis.
• a control centre, which decides how to respond
and
• effectors, which carry out the commands of the
control centre and make the necessary
adjustments to the system.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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In mammals, which maintain fairly constant body
temperatures, it is the Hypothalamus at the base of
the brain which monitors blood temperature and
sends out command messages for negative
feedback, rather like the oven thermostat system.
Complete Worksheets 1,2 & 3.
Page 6
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KISS Resources for the NSW Syllabus.
2. Temperature Regulation
®
keep it simple science
Temperature Control
in Mammals
In a healthy human the internal “core” temperature of
the body is about 37oC and is maintained within
about 0.5oC at all times. If the body temperature goes
up, or down, by more than about 4oC it is a lifethreatening situation.
Control of body temperature is achieved as shown
in this schematic diagram:
Main Parts of the System
The Receptor and Control Centre is the
Hypothalamus at the base of the brain. Special
cells constantly monitor the temperature of blood
flowing by. If the temperature varies by even a
fraction of a degree, nerve messages are sent to
the effectors.
The Effectors include blood vessels, sweat glands,
endocrine (hormone) glands, muscles and body
hairs.
BODY TEMPERATURE REDUCES,
BLOOD COOLS
p.
em d
t
d
e
oo ur
Bl eas
m
to
Effectors
Nerve
Command
COOLING MECHANISMS
Blood vessels dilate.
Sweat glands activated.
Hair lowered.
Metabolic rate reduced.
INSPECTION COPY
for schools only
Cerebrum
IF BODY TEMPERATURE
IS TOO HIGH
llu
m
Hypothalamus
monitors blood
temperature
Nerve
Command
p.
em d
t
od ure
Blo eas
m
be
to
Effectors
re
Ce
IF BODY TEMPERATURE
IS TOO LOW
WARMING MECHANISMS
Blood vessels constricted.
Muscles begin “shivering”.
Hairs erected (goose bumps).
Metabolic rate increased.
BODY TEMPERATURE INCREASES,
BLOOD WARMS
What the Effectors Do
Blood Vessels
Dilation (widening) of veins,
arteries and capillaries near the
skin allows more blood to flow
out near the skin surface.
This allows more body heat to
escape from the skin, thus
cooling the body.
Body Hairs
Each hair on your body has a
tiny muscle at its base which
can cause the hair to stand up
erect and give you “goose
bumps”. This traps a layer of still
air against the skin and helps
insulate and prevent heat loss.
If the hair follicle muscle is
Constriction (narrowing) of
relaxed the hair lies flat and
blood vessels causes less
allows more heat loss.
blood to flow near skin. Less
heat flows out to the skin to be
lost, so
more body
Sweat Glands
heat is
When activated, the sweat glands secrete perspiration.
retained.
The water evaporates from the skin, carrying away body
heat... this has a powerful cooling effect.
Biology 9.2 “Maintaining a Balance” PhotoMaster
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Page 7
Muscles
Nerve signals can cause the skeletal
muscles to begin “shivering”. This
extra muscle activity generates
more heat to warm the body.
Hormones
are chemicals which control
various body functions.
The hormone thyroxine
(produced by the thyroid gland in
the neck) controls the rate of
metabolism. It is under the
control of the hypothalamus, via
another hormone from the
pituitary gland.
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
The Temperature Range of Life
®
Homeostasis allows an organism to maintain its cells at a temperature close to
the optimum for its enzymes. This allows its metabolism to run efficiently,
despite changes in the temperature of the surrounding environment.
However, homeostasis has its limits, and no organism can remain active and thriving under
the full range of temperatures of the biosphere of the Earth. Different organisms have
adapted to survive in extreme cold, or in extreme heat, but never both.
keep it simple science
Extreme Heat
There are thermophilic bacteria (members of the
Archaea) which live and thrive in volcanic hot
springs at temperatures up to 120oC.
In terrestrial environments such as hot deserts, the
temperature can often reach 40oC and sometimes
as high as 60oC. Many plants and animals are
adapted to survive these extremes, but few remain
active in this heat. Generally in deserts the animals
seek shelter and become inactive, while plants
shut down their metabolism and merely survive.
Cold Water Environments
Even when ice forms on the surface, water
environments rarely fall below +4oC, and are
remarkably stable in temperature. Life-forms do
not need to cope with change, although mammals
or birds need serious insulation to stay warm. It is
the terrestrial environment that is more of a
challenge.
Extreme Cold
There are many organisms which can survive
extreme cold, but few that remain active. Certain
types of algae and photosynthetic bacteria are
found to live within the snow and ice near the poles
and are still metabolically active at temperatures as
low as -10oC.
Generally however, plants and animals cannot tolerate
their body temperature going below 0oC, since ice
crystals forming in cells can destroy membranes and
kill cells. Also, the chemical reactions of metabolism
run so slowly at low temperature, that life functions
are not possible.
Of course, many animals do live and survive in the
cold because they can produce their own body heat
(mammals and birds) and are equipped with body
insulation and homeostatic mechanisms to maintain
their core temperature despite the cold environment.
Perhaps the world champions are the Emperor
Penguins which maintain core body temperatures
around +33oC throughout the Antarctic winter in air
temperatures as low as -50oC.
Temperature Control in Ectotherms
Ectotherms are the “cold-blooded” animals, such as reptiles, amphibians, insects, fish, worms, etc.
“Cold-blooded” is a misleading term and is best avoided, since these animals are NOT always cold,
but rather they rely on the outside environment for their body heat...
they do not generate heat internally like a mammal or bird.
Ectotherms have a variety of adaptations, many of
them behavioural, to regulate their body
temperature and keep it within the range in which
they can be active; generally 10-30oC.
For example, the BlueTongue Lizard will lie in
a sunny spot with its
body flattened and
turned side-on to the
INSPECTION
Sun on a cool morning.
This way it absorbs
for schools
heat more quickly to
get its body
temperature high
enough to become
“Bluey” sun-baking
active.
As the day becomes hotter, the lizard will turn
facing the Sun to absorb less heat, and seek shade
to avoid over-heating.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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In prolonged periods of cold weather, such as
winter in the Australian Alps, ectotherms cannot
remain active.
Animals such as the Copperhead
Snake and the Corroboree Frog
seek shelter underground and
become dormant throughout the
winter.
COPY
only
In a process similar to the
hibernation of bears, the animal’s
heartbeat and breathing slow down,
their metabolism almost stops and
their body temperature chills to
only just above freezing.
As long as they are more than about 50
centimetres underground, the ground will not
freeze even though buried in snow for several
months. If they haven’t burrowed deeply enough
they will freeze to death!
Page 8
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Temperature Control in Endotherms
Endotherms are the animals which produce their own internal body heat
and maintain a constant body temperature... the birds and mammals.
All endotherms rely heavily on having body
insulation... fur, feathers or blubber (fat). Humans
rely mostly on technology to provide heaters,
jackets, wetsuits, gloves, etc, to protect our fragile
bodies from extreme
temperatures.
What do endothermic animals in
the wild do?
Firstly, they have all the
responses for homeostasis
described earlier... dilation or
constriction of blood vessels,
shivering and sweating etc. As
well as these, they may have
extra adaptations to help
regulate their temperature.
In hot environments such as the Australian
deserts, mammals such as the Red Kangaroo or
the Bilby, have many adaptations to help them
cool their bodies:
Large ears, with many blood
vessels, increases the surface
area for heat loss.
They seek shade in the heat of
the day.
Panting evaporates water from
the mouth and throat, and
cools the blood.
INSPECTION COPY
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In the desert, big ears are cool!
They may lick their forearms.
The evaporation of saliva cools
their body the same as
sweating.
In the cold, endotherms go for thick fur coats (Wallaroo) or layers of fat (Australian Fur Seal).
Penguins, such as the Fairy Penguins along Australia’s southern coast, have a special
“blood shunt” in their legs. In warm conditions the shunt is closed and blood flows normally
to the feet. Since the feet are about the only part of their body not well insulated, in cold water
they could lose a lot of body heat. So in cold water the flow of blood from body toward
the feet is “shunted” via a special vein with a valve in it, back into the body.
The feet receive virtually no blood, and this conserves body heat.
Responses of Plants to Temperature Change
Plants cannot respond to temperature change by moving away or hiding.
To cope with temperature extremes they must have structural or physiological adaptations.
To cope with seasonal cold weather, many plants
(especially in the northern hemisphere) are
deciduous... they shed their leaves and basically
shut down their metabolism for the winter, rather
like an animal hibernating. Their leaves cannot be
protected from freezing, so the strategy is to lose
the vulnerable parts, survive until next spring, then
grow new leaves.
Coping with heat is another story.
If there is plenty of water
available, such as in a
tropical jungle, then the
plants cool themselves by
allowing maximum
evaporative cooling. The
leaves open their many
stomates and allow
transpiration to occur. The
evaporation has a cooling
effect, in the same way that
sweating cools an animal.
Biology 9.2 “Maintaining a Balance” PhotoMaster
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When it is hot and DRY, they have a problem.
Desert plants tend to have very small leaves and
thick, “stocky” shaped stems. This reduces the
surface area being hit by heat radiation from the
Sun, and helps prevent over-heating. The cacti
plant group have taken the strategy to the limit...
their leaves are spines, and stems are “fat” and
rounded. They are also light coloured to reflect a
lot of the radiant heat away. They have very few
stomates.
The sclerophyll plants of
Narrow,
Australia (e.g. gum trees) also
drooping
have small narrow leaves to
gum tree
reduce heat absorption from
leaves
the Sun. Their other “trick” is to
allow the leaves to droop. This
allows them to catch light for
photosynthesis in the cooler
morning when the Sun is low,
but avoid absorbing heat when
the Sun is overhead at midday.
They have few stomates, and
close them in dry times.
Page 9
Complete Worksheets 4 & 5.
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
®
keep it simple science
3. Internal Transport Systems
Internal Transport in Mammals
As with most animals, for internal transport mammals rely on their Circulatory System...
the blood, heart and blood vessels; veins, arteries and capillaries. A basic knowledge of
how the system operates was covered in Preliminary Topic 2.
Blood
You will
have
examined
blood
under a
microscope
and seen
something
like this:
RED BLOOD
CELLS
INSPECTION COPY
for schools only
You need to be able to sketch diagrams
of blood cells, and have an idea
of their relative sizes.
Sketch of Blood Cells
Size
7 mm
Red
Cells
Blood is made of a liquid (“plasma”) with
millions of special blood cells carried in it.
There are about 600 red
cells to 1 white cell
Most
white cells
are much
larger than
red cells
no
nucleus
Shaped like a
donut with the
hole closed over
large, irregular nucleus
There are 2 general categories of these cells:
Red Blood Cells contain the red pigment haemoglobin, which carries oxygen.
This is covered in more detail later in this topic.
White Blood Cells come in a huge variety of types, but all are involved with
defence against disease. This is covered in a later topic.
Blood Vessels
As the blood flows around the body it is always carried inside tubes, or vessels:
Arteries
carry blood from the heart out to the
body tissues. The walls of an artery are relatively
thick and muscular to withstand the high pressure in
the blood when the heart pumps.
Veins carry blood back from the
body tissues
to the heart. The blood here is under lower
pressure and the walls of a vein are relatively thin.
With little pressure to push blood forward, it is the
contraction of the surrounding muscles which
helps push the blood along.
Some veins contain valves to prevent back-flow of
the blood.
Thick, muscular walls
Artery walls are very elastic, and when a pulse of
high pressure blood passes through, they expand
outwards and then contract again, helping to push
the blood along. This rhythmic expanding and
contracting is what you can feel as your “pulse”
wherever an artery is close to the skin, such as in
your wrist or throat.
VEIN Cross-Section
blood
flow
Relatively thin walls are
often squashed by
surrounding muscles.
Side view of VEIN
showing a valve.
Blood can flow one way,
but not back the other.
Capillaries are the tiny blood vessels which form a network throughout the tissues so that every
living cell is close to the blood supply. The walls of a capillary are only 1 cell thick, so diffusion of
substances from blood to cells (or cells to blood) is easily achieved.
The inside of a capillary is so small that red blood cells often travel through it in single file.
Biology 9.2 “Maintaining a Balance” PhotoMaster
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KISS Resources for the NSW Syllabus.
Substances Carried in the Blood
®
keep it simple science
Prac Work: CO2 and Acidity
Oxygen O2 is carried in the red
blood cells by haemoglobin.
You will have carried out an
experiment to see the effect of
dissolved CO2 on the pH of water.
Carbon Dioxide CO2
is partly carried by the haemoglobin
in red blood cells, but most of it is
carried in the blood plasma, in the
form of bicarbonate ions (HCO3-)
You might have chemically produced
some CO2 and bubbled it through
water. Using a pH meter, or Universal
Indicator, you will have measured any
change in the pH of the water.
Water is carried as the liquid
solvent of blood plasma.
Salts, Sugars &
Amino Acids
You would have found that the pH
went down... i.e. the water became
more acidic.
These are nutrients absorbed from
the Digestive System. They are
generally water soluble and are
carried dissolved in the blood plasma.
Lipids (Fats)
absorbed from the digestive system are “packaged” in a
protein coat which makes the fat molecule miscible in
water. This means that, while not fully dissolved, the
molecules can be dispersed in water and carried without
joining together into droplets of fat and separating from
the water.
Explanation and Chemistry
Carbon dioxide reacts with water to
form carbonic acid
CO2 + H2O
Carbonic acid is a weak acid which
partly ionises
H+
H2CO3
In this form they are carried dispersed in the blood
plasma.
Nitrogenous Wastes
such as urea, are water soluble and carried dissolved in
the blood plasma.
H2CO3
Hydrogen ion
makes water more acidic
+
HCO3-
Bicarbonate ion.
This is how CO2 is
carried in the blood.
INSPECTION COPY
for schools only
The Need to Remove Carbon Dioxide
Carbon dioxide doesn’t just dissolve in water, it reacts to form a weak acid.
CO2 + H2O
H2CO3
H+
carbonic
acid
It’s the hydrogen ions that create
problems. Hydrogen ions are acids and
can lower the pH of a cell or the blood.
At the concentrations produced by a
typical cell, the hydrogen ions could easily
lower the pH of the cytoplasm by 0.5 pH
unit or more. This might not sound like
much, but it could be life-threatening.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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+
HCO3-
hydrogen bicarbonate
ion
ion
Remember that enzymes are very
sensitive to pH changes and quickly
change shape and lose their catalytic
activity. This would be disastrous for cell
metabolism.
To avoid this problem, CO2 is carried
away in the blood as rapidly as it is
produced in the cells.
Page 11
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
Changes to the Blood as it Circulates
Nutrients &
Nitrogenous Wastes
As the blood flows through capillaries in the
digestive system it picks up sugars, amino acids,
salts, water, vitamins, etc that have been
absorbed from the gut. (However, lipids are first
absorbed into the lymphatic “drains” and enter
the blood much later)
This blood from the gut is collected in a vein
which takes it directly to the liver. Here some of
the nutrients may be absorbed from the blood for
storage or chemical processing (e.g. glucose is
extracted from the blood and polymerised to
form glycogen for storage in the liver). Also in the
liver, large amounts of the waste chemical urea
is added to the blood to be carried away for
excretion.
Later, as blood flows through capillaries in body
tissues such as muscle or bone, nutrients are
absorbed from the blood into the cells which
need energy (glucose) and new chemical building
blocks (amino acids, lipids).
Sooner or later, every bit of blood flows through
the kidneys which extract the urea and excess
salts and water for excretion as urine.
Respiratory Gases O2 & CO2
Gas exchange and transport is essential for
delivering oxygen to cells and removing CO2.
CO2
O2
Oxygen
Air
Lungs
Carbon
dioxide
Blood
Air
Blood
Heart
CHANGES IN OXYGEN AND
CARBON DIOXIDE
AS THE BLOOD CIRCULATES
Arteries
keep it simple science
As the blood circulates around the body its chemical composition
undergoes a number of changes...
Veins
®
INSPECTION COPY
for schools only
Blood flow
in Lungs
Oxygen
Blood
Arteries
Heart
Some Nutrients
into storage
Wastes
into
blood
Veins
CHANGES IN NUTRIENTS, WATER & WASTES
AS THE BLOOD CIRCULATES
Body tissues
Liver
Digested
Nutrients
move
into blood
Gut
Kidneys
Wastes and
excess water & salts leave blood.
Excreted in urine.
Blood flow
in Body tissues
Nutrients move from blood into cells
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Carbon
dioxide
Cells
O2
CO2
Cells
Blood
As blood passes through capillaries in body
tissues, oxygen is released from the haemoglobin
molecules and diffuses along the concentration
gradient into the body cells. There is always a
concentration gradient favouring this because the
cells are constantly using up oxygen for cellular
respiration.
Meanwhile, the concentration of carbon dioxide is
high because of its constant production by cellular
respiration, so it diffuses from the cells into the
blood.
When the blood gets to the lungs the opposite
occurs. Inside the alveoli (air sacs of the lungs) the
air has a very high concentration of oxygen and is
very low in CO2. Therefore, oxygen diffuses into the
blood, while carbon dioxide diffuses from the blood
into the air.
Page 12
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KISS Resources for the NSW Syllabus.
The Importance of Haemoglobin
®
keep it simple science
The high concentration of dissolved CO2
lowers the pH of the blood slightly. This
causes the haemoglobin proteins to
change shape slightly and release the
oxygen molecules.
Blood is red because of the many red
cells, and red cells are red because
they are packed with the red-coloured,
iron-containing protein haemoglobin.
In the lungs, where the oxygen
concentration is very high, some
oxygen dissolves in the moisture lining the alveoli then
diffuses into the blood and dissolves in the plasma..
HbO2
Oxygen is not very soluble in water, however, and if that’s all
there was to the story, then our blood could never carry
enough oxygen to supply our cells.
Haemoglobin molecules have a great attraction for oxygen
molecules and quickly “grab” any O2 molecules available.
Because of this, our blood can carry thousands of times more
oxygen than would be possible by simply dissolving oxygen in
the blood plasma.
Hb
+
O2
abbreviation for
Haemoglobin
HbO2
“Oxyhaemoglobin”
When the oxygenated blood gets to the body tissues the
reverse happens.
Hb
+
O2
The oxygen diffuses into the cells, and the
freed haemoglobin molecules can pick up
some of the CO2 molecules and carry them
back to the lungs.
Adaptive Advantage
Haemoglobin increases the oxygencarrying ability of blood enormously. Its
use in some ancient creature’s primitive
circulation system gave that animal a huge
advantage to survive. With more oxygen, it
could move faster, grow faster and larger
and breed more successfully.
Many animal types descended from that
ancient success. Haemoglobin is a great
adaptation.
INSPECTION COPY
for schools only
Oxygen Saturation & Its Measurement
The concentration of O2 and CO2 in the
blood is of great interest to doctors
monitoring a patient, or an athlete in
training, or even to a pilot or mountainclimber at high altitude.
The most important measurement is
“percentage oxygen saturation”
(%SpO2). A reading of 100 would
mean that 100% of all haemoglobin in
an artery is totally saturated with
oxygen. Readings between 95-100%
indicate good health, fitness and
adequate oxygen supplies.
Lower readings (e.g. 80%) could
indicate:
• respiratory or circulatory problems
in a patient.
• lack of fitness, or excessive exertion
in an athlete.
• need for supplementary oxygen for
a pilot or climber.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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In years gone by, %SpO2 was measured by
taking blood samples and carrying out
complex chemical testing. With modern
technology, however, the readings are done
instantly and non-invasively by a small,
portable instrument clipped onto the end of a
finger, ear lobe or foot.
The “Oximeter” works by sending red light
and infra-red beams through the flesh. The
amount of each light absorbed by the
haemoglobin gives a direct measurement of
%SpO2, because haemoglobin with, or
without,
Foot-clamp Oximeter measures
oxygen
%SpO2 in a young patient
absorbs
these light
beams
differently.
Page 13
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
®
Products of Blood Donation
keep it simple science The Australian Red Cross Blood Service collects about a million blood donations per
year. Most of this blood is used for people who need regular treatment with
blood products for conditions such as leukemia. Only a very small amount is kept as whole blood for
emergency transfusions. Most donated blood is separated into about 20 different fractions or products,
so each donation can treat many different patients.
The main blood products are:
Red Cell Concentrate
Plasma
which contains about twice as
many red cells as normal, is used to
boost the oxygen-carrying capacity
of patients with
anaemia or after blood loss, such
as might happen in a motor
accident.
is the liquid part of the blood
and is often given in emergency
to boost the volume of blood
following severe blood loss.
Cryoprecipitate
is a fraction collected from
plasma and contains blood-clotting
factors. It is used to treat
severe bleeding.
Platelet Concentrate
is given to patients who need extra
blood-clotting capability, such as
leukemia sufferers, or following
severe blood loss.
Factor VIII and Monofix
are extracts from plasma used to
treat people who have haemophilia... an
inherited, incurable disorder in which
the blood will not clot properly.
These blood products allow patients
to lead a relatively normal life.
White Cell Concentrate
is given to patients needing a boost
to their immune system, perhaps
following a severe infection.
Artificial Blood?
The Need for Artificial Blood
Fresh blood cannot be stored for long, and
many parts of the world lack the necessary
storage facilities.
Many blood products can set off immuneresponses in long-term patients, even after
correct blood-typing. (Similar to “rejection”
of a transplanted organ)
Donated blood can carry diseases, such as
hepatitis or HIV.
Many of these problems could be solved by
the use of an artificial blood which is easy
to store and can be made disease-free.
INSPECTION COPY
for schools only
Haemoglobin-Based Oxygen Carriers
is one of the areas of current research.
Haemoglobin extracted from animal blood can
be purified and treated so that it is disease-free
and cannot cause any allergic or “rejection”
responses in patients.
The products can be stored for years at room
temperature, and promise to be highly effective
at carrying oxygen and releasing it into the
tissues.
Currently undergoing clinical trials, but not yet
approved for medical use. Recent trials failed.
Perfluorocarbon-Based Substitutes
Another area of research aims to develop a truly artificial blood substitute. The most promising base
chemicals are the “perfluorocarbon” compounds. These can carry up to 5 times more oxygen than
blood and can be stored indefinitely at room temperature.
They can be made totally sterile and disease-free.
At least 5 different products are being tested and trialled (USA),
but none are yet approved for medical use. Trials in 2008 produced very negative results.
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Page 14
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
®
keep it simple science
Transport Systems in Plants
Hollow, dead cells, joined
end to-end forming a tube
Xylem Tubes Carry Water
Xylem tubes are dead, hollow cells, joined endto-end forming a continuous tube from root to
leaf. The xylem tubes transport water (and
dissolved minerals) generally upwards from
roots to leaves.
INSPECTION COPY
for schools only
Cell walls
re-inforced
with rings
and spirals
of lignin
Photo at left: Scanning Electron Microscope (SEM)
image of plant stem showing hollow xylem tubes.
Creative Commons Attribution-Share Alike 3.0 unported licence.
Image by McKDandy at en.wikipedia.
How do xylem tubes lift water upwards against the force of gravity?
“Transpiration” is the
evaporation of water from the
leaves. When the stomates are
open, water can constantly
evaporate, creating a tension, or
“pull” in the remaining water in the
leaves.
Water molecules are quite strongly
attracted to each other and tend to
cling tightly together. This force is
called “cohesion” and is the reason
that water tends to form droplets...
little blobs of water that cling
together.
So, when water evaporates from
leaves and creates a “pull” force,
each water molecule pulls on those
behind it because of the cohesion.
Each molecule pulls others upward
and so the entire column of water in
a xylem tube moves upwards to
replace the water lost by
transpiration. So water is pulled
upwards by a combination of
transpiration and cohesion. This
flow is called the “transpiration
stream”.
Cohesion & Adhesion
Another factor which helps the process is called
“capillarity” or the “capillary effect”. This is the
way that water can “climb up” the walls of a
container forming a meniscus in a test tube, for
example. This happens because water molecules
are not only attracted to each other (“cohesion”)
but also to some other substances such as glass
or the inside of a xylem tube. This attraction is
called “adhesion”.
In very narrow tubes (“capillaries”) the water will
climb upwards against gravity because of
adhesion, and drag more molecules along by
cohesion. This happens in xylem and helps lift
water upwards.
The “veins” in a leaf contain both the xylem &
phloem tubes. Veins also act as “ribs” to help
keep leaves in shape.
Active & Passive Transport
Note that the flow of water in the xylem costs the
plant nothing in energy terms... it is “passive”
transport.
In contrast, the other transport system in plants
is an “active transport” system... the plant must
constantly supply energy to make it happen.
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Page 15
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KISS Resources for the NSW Syllabus.
®
keep it simple science
Phloem Tubes Carry Food Nutrients
While the xylem tubes are formed from dead cells, the phloem are
living cells joined end-to-end. The ends of each cell are perforated (“sieve plates”)
so each cell is open into the next and they form a continuous tube.
The transportation of nutrients through the
Phloem Tubes is called “Translocation”.
Sugars are
actively
transported in
the flow of
cytoplasm within
the cells.
INSPECTION COPY
for schools only
Sieve plate between cells.
PHLOEM CELL
alive and filled with cytoplasm.
Flow of cytoplasm carries sugars
through each cell.
Translocation Works 2-Ways
While the xylem is a one-way flow system, the
phloem system can carry food (especially
sugars) in either direction.
“Companion cell”
has many
mitochondria to
provide ATP to the
phloem cell
If a lot of photosynthesis is occurring, the
phloem will carry sugar to storage sites in
roots or stem.
If photosynthesis is not possible for an
extended time, then the phloem will
carry sugars back from the storage
sites to feed the leaf cells, or supply
a growing flower or fruit.
After this page,
complete worksheets
6, 7, 8, 9 & 10.
What Makes the “Sap” Flow?
The flow of nutrients through the phloem is
caused by pressure differences between the
“Source” tissues and the “Destination”.
Sugar is carried into cells
by active transport,
requiring energy. Water
flows in due to osmosis,
raising the pressure.
SOURCE
Higher
Pressure
PH
The pressure difference is osmosic pressure,
generated by active transport of sugars causing
water to flow into, or out of cells.
LO
Translocation...
how it works
EM
TU
ca
S
slo
BE
n
Tra
tio
Sugar solution
flows due to
pressure
differential
n
Sugar is removed by
active transport, requiring
energy. Water flows out of
cells due to osmosis,
lowering the pressure.
DESTINATION
Lower Pressure
The “veins” in a leaf are bundles of tubes with both xylem AND
phloem. There are also many strong fibres which add strength and
help keep the leaf in shape so it gathers light without “drooping”.
Biology 9.2 “Maintaining a Balance” PhotoMaster
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Page 16
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
®
keep it simple science
4. Excretion & Water Balance
The Importance of Water
Life cannot exist without water. All living cells are at least 75% water.
The functions of water in living things include:
Water is the Solvent of Life
All the chemical reactions of metabolism
take place in water solution, and the
transport of materials in cytoplasm, blood
or phloem takes place mainly in water
solution.
Water Regulates
Temperature
Water has a very high specific heat
capacity. This means it can absorb (or
lose) relatively large quantities of energy
with minimal temperature change. This
helps stabilise the temperature of all
living things.
Water also has a very high heat of
vaporisation. This means that when it
evaporates it absorbs huge amounts of
heat. This is why evaporation of
perspiration from the skin has such a
cooling effect.
Water Supports &
Cushions Cells & Organs
Many plants and animals rely on water for
body support. Non-woody plants pump
their cell vacuoles full of water to make
cells “tight” and keep stems and leaves
upright. Animals such as worms rely on
the hydraulic pressure of water in their
tissues to support their body and maintain
its shape.
In vertebrate animals the water solutions
in the tissues helps to cushion organs
against bumps and impacts. (e.g.
cerebrospinal fluid around the brain)
Water is Involved
in Life Chemistry
Water is a reactant or product of many
metabolic reactions. The reactions of
photosynthesis and cellular respiration are
just two of the many examples.
Homeostasis of Water & Salts
It’s not just the water that is important, but its
concentration, and the concentration of
substances dissolved in it, such as salts.
If the concentrations are not kept at the
correct levels, then osmosis may cause
problems. Cells could lose water and
dehydrate, or gain too much water and be
damaged or even burst open by increasing
pressure within.
Major Internal Organs
in a Human
INSPECTION COPY
for schools only
Lungs
Heart
THE CONCENTRATION OF WATER &
DISSOLVED SALTS MUST BE MAINTAINED
Liver
Stomach
Kidney
THIS IS ANOTHER EXAMPLE OF
HOMEOSTASIS
Ureter
IN MOST ANIMALS
WATER BALANCE IS REGULATED
BY THE KIDNEYS
Bladder
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Page 17
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
Kidneys Also Excrete Metabolic Wastes
®
keep it simple science
INSPECTION COPY for schools only
Metabolic Wastes
The many chemical reactions of metabolism
sometimes produce chemicals which are toxic to
cells, often because the chemical, when dissolved
in water, can change the pH and reduce enzyme
activity.
Therefore, it is essential that these wastes are
removed (“excreted”) as soon as possible. The
major wastes are:
Nitrogenous wastes (contain nitrogen)
These wastes are produced mainly from the
metabolism of proteins.
There are 3 main compounds that can be
produced:
Ammonia in most aquatic animals.
Uric acid in birds, reptiles & insects.
Carbon dioxide
is produced by cellular respiration. As covered
previously, it will lower the pH (it’s acidic). It is
carried in the blood and excreted by the lungs.
Urea in mammals and amphibians.
Excretion & Water Balance in Fish
Fish produce the waste ammonia which is very alkaline and toxic. Luckily it is very soluble in water.
Since they live surrounded by water, fish simply excrete ammonia from their gills by simple diffusion.
Their kidneys are used not so much for excretion, but for maintaining their water balance.
Freshwater fish and saltwater fish have opposite problems with water balance.
SALTWATER FISH
Constantly
drink to
replace
water
(but get
salt, too)
FRESHWATER FISH
Water loss from tissues by osmosis
(mainly through gills)
Gills excrete Ammonia,
Carbon Dioxide and
excess salt
Kidneys produce
small amounts of
urine to
save water
Tissues gain water by osmosis
(mainly through gills)
Do not drink
Gills excrete Ammonia &
Carbon Dioxide, and
actively absorb salts
Kidneys produce a lot
of dilute urine to
remove water
from body
Excretion in Terrestrial Environments
The fish can get away with production of
highly toxic ammonia. They can rely on
constant diffusion of ammonia from the
blood in their gills into the water
environment which surrounds them.
Consequently, in land-living animals
nitrogenous wastes are produced not as
ammonia, but the less toxic compounds
urea (mammals) or uric acid (birds,
reptiles, insects).
In terrestrial environments, waste gases
can do exactly the same; that’s how
carbon dioxide is excreted... by simple
diffusion from the blood to the air in the
lungs.
Excretion is via the kidneys. The simple
processes of diffusion and osmosis are
not adequate to achieve this.
However, nitrogenous wastes are not
gaseous and need to be excreted in water
solution.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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For simple diffusion to achieve excretion it
would require huge amounts of water to be
excreted too, and no terrestrial animal can
afford to lose so much water, especially in a
desert.
Page 18
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
How the Kidneys Work in Mammals
®
keep it simple science
Each kidney contains about 1 million nephrons. Each nephron is a
complicated tangle of blood vessels and renal tubules (= small
tubes). What happens in a nephron is:
Artery
carries blood
into kidney.
Vein
carries blood
out of kidney.
Filtration
removes some of the water and many small dissolved molecules
(including the waste urea) from the blood into the renal tubules. This
occurs because the walls of the glomerulus are “leaky” and the
blood is under high pressure.
Reabsorption
then occurs to move useful substances back into the blood.
This is achieved by:
Active Transport of sugar, amino acids & salts from the renal
tubules back into the blood. This requires energy to be used to
transport these chemicals across the cell membranes, against a
concentration gradient.
Osmosis then occurs, which causes water to flow from the
tubules back into the blood. This is Passive Transport and costs
the body no energy.
Bladder
stores urine.
Ureter
carries
urine to
bladder.
Urethra
drains urine from bladder.
Renal Tubules
Glomerulus
a coiled blood vessel
Kidney
removes
wastes from
blood and
adjusts
water
& salt balance.
THE NEPHRON
of the KIDNEY
(simplified)
Blood in
from artery.
This blood
contains urea
Filtration
occurs
here
Bowman’s Capsule
a “receiving cup” to
collect the filtrate
liquid from the
blood
Reabsorption
occurs
here
Urine
flows to
collecting
duct
Blood Capillary
Network
shown in
simplified form.
Blood out
to vein
This blood has had wastes removed, and
water balance adjusted for Homeostasis.
Filtration is the process in which some
water and many dissolved substances
(including sugar, salts & urea, BUT NOT any
cells or blood proteins) leave the blood and
flow into the renal tubules.
then via
Ureter to
Bladder,
for
excretion.
INSPECTION COPY
for schools only
Reabsorption is the process in which
any useful substances (such as sugars &
amino acids) are absorbed back into the
blood. Water & salts are also reabsorbed, but
in varying quantities... the body is adjusting
water balance for Homeostasis
Urea is not reabsorbed back into the blood.
Urea and some water continue along the tubule. This liquid is URINE.
Urine flows into the Ureter and is carried to the Bladder for storage.
When the bladder becomes full, the urine is excreted via the Urethra.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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Page 19
Inspection Copy for Schools only.
KISS Resources for the NSW Syllabus.
The Kidneys & Homeostasis
®
keep it simple science The kidneys are not just used for excretion. As well, the kidneys can adjust the “water balance”
of the body by allowing more, or less, urine to be produced. In this way the kidneys are a vital
part of homeostasis.
Once again, the Hypothalamus is involved, but the control mechanism is by hormones... chemicals which are released
into the blood and exert a control function on some “target organ”. In this case the hormone is called “Anti-Diuretic
Hormone” (ADH) and the target organ is the kidney, specifically the nephron tubules.
BODY RETAINS MORE
WATER, excretes less urine.
Urine is more concentrated
ADH causes more
reabsorption of water
from kidney tubules
Note the typical pattern of a
negative feedback system
c
lan
a
b
alt u r e d
S
/
s
ter e a
Wa m
Cerebrum
n
ala
b
t
d
al r e
r/S a s u
e
t
e
Wa m
BODY PASSES MORE
WATER, excretes more urine.
Urine is more dilute.
Ce
re
ll
be
WATER LEVEL IN
BODY TOO HIGH
um
ce
HYPOTHALAMUS
&
PITUITARY GLAND
Less ADH causes less
reabsorption of water
from kidney tubules.
to Pituitary Gland
WATER LEVEL IN
BODY TOO LOW
e
Nerve Command
to Pituitary Gland
Nerve Command
Pituitary Gland
releases more ADH
(Also nerve signals to brain
cause “thirsty” feeling so
you will want to drink)
Pituitary Gland
releases less ADH
(Also nerve signals to brain
cause feeling that you do
NOT want to drink)
Kidney Structure & Nephrons
Practical Work
You may have dissected a kidney in your
laboratory work in class.
DISSECTED
KIDNEY
You need to be able to relate the gross
structure of the kidney to the structure
and functioning of the nephrons.
Renal Cortex
Dark red in colour due
to the many blood
capillaries of the
nephrons
Medulla
Lighter in colour...
less blood vessels.
Here many
collecting ducts
carry urine to the
ureter.
This diagram may help you understand
your kidney dissection a little better.
Artery & Vein
INSPECTION COPY for schools only
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Ureter carries
urine to bladder
Page 20
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KISS Resources for the NSW Syllabus.
Water & Salt Balance Hormones
®
keep it simple science
The hypothalamus monitors the blood flowing through it for the “osmotic balance” of water
and dissolved salt. If the body is even slightly dehydrated, more ADH is released by the
pituitary gland and circulates in the blood stream.
The effect of ADH is to alter the permeability of the membranes lining the tubules of the
kidney nephrons. Increased ADH levels make the membranes more permeable to water,
so more water is reabsorbed back into the blood. This means that less urine is
produced.
If the body is over-hydrated, the production of ADH is reduced. This causes the tubules
to become less permeable to water so less is reabsorbed into the blood. The result is
more urine being produced.
ADH is the hormone controlling the water levels, but this is only part of the “osmotic
balance” story... the salt levels can be controlled too... see below.
INSPECTION COPY
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Control of Salt Levels by Aldosterone
Sitting on top of the kidneys
are the “Adrenal Glands”
which produce a variety of
hormones. One of the adrenal
hormones is Aldosterone
which controls reabsorption
of salt from the nephron
tubules.
Adrenal
Gland
If salt levels are too low, special cells in
the adrenal glands increase the
production of aldosterone into the
bloodstream. This causes the cells lining
the nephron tubules to actively transport
more sodium ions back into the blood.
Chloride ions follow the sodium, and so
more salt is reabsorbed.
If salt levels are too high, the adrenal
glands produce less aldosterone so less
salt is reabsorbed, and the excess salt is
excreted in the urine.
Between ADH and aldosterone the body
maintains a constant “osmotic balance” of
water and dissolved salt... Homeostasis.
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Addison’s Disease & HRT
Addison’s Disease occurs when a
person’s adrenal glands do not produce
enough aldosterone. Their nephrons
constantly fail to reabsorb salt and so the
“osmotic balance” of the body is
chronically out of order.
This leads to a variety of problems and
malfunctions throughout the body
involving the heart, intestines and liver,
and may cause psychological disorders
as well.
This is a disease that can be sucessfuly
treated by “Hormone Replacement
Therapy” (HRT).
A person with Addison’s Disease can be
treated with appropriate doses of steroid
hormones (usually cortisone) and
although they cannot be totally cured,
they can lead a normal, symptom-free life
on HRT.
Page 21
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Renal Dialysis
If a person’s kidneys cease functioning properly he/she can no longer remove toxic
wastes such as urea from the blood, nor maintain homeostasis of “water balance”.
In the case of complete kidney failure, this condition
can be fatal within about 3 days without treatment.
Dialyser cartridge
Over the past 40 years or so, many people have
been successfully treated by receiving a kidney
transplant. However, they may have to wait months
or years to find a suitable organ donor.
Meanwhile, they need to be treated by Renal
Dialysis... the use of medical technology to remove
wastes from the blood artificially. In
effect, a renal dialysis machine is an
“artificial kidney”.
Dialyser Cartridge
Blood in
The key component of a modern dialysis machine is
a disposable dialyser cartridge.
The patient’s blood flows through the cartridge from
one end to the other inside thin “dialysis tubes”.
These tubes are made from a plastic which is semi-permeable.
Dialyser cartridge
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The tubes are surrounded
by a “dialysing fluid”
which flows through the
cartridge in the opposite
direction.
Dialysing
fluid out
Blood flows
through
dialysis
tubes
Dialysing
fluid in
The dialysing fluid
Blood out
contains water, salts,
sugars, minerals etc
exactly as in healthy blood plasma. Since
there is no concentration gradient for these chemicals they do not diffuse in or out of
the blood. However, the wastes such as urea are in higher concentration in the blood,
and so they diffuse from the blood into the dialysis liquid, which is later disposed of.
Comparison of Renal Dialysis with Natural Kidney Function
Differences
Similarities
•Both processes remove
urea and other wastes from
the blood.
• Kidney function involves the 2 steps of filtration
and reabsorption; dialysis involves only 1 step of
diffusion of wastes from blood.
•Both rely on movement of
dissolved substances
through semi-permeable
membranes.
• In a kidney, movement across membranes is
achieved by both active transport and by passive
osmosis and diffusion; dialysis involves only
passive diffusion.
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Water Balance in Australian Animals
keep it simple science
The different conditions of each environment
dictate what an animal must do to to achieve
homeostasis of its “water balance”. In each
environment there are different problems to be
overcome, and the animal’s body organs must
respond appropriately. Exactly how homeostasis is
achieved will be reflected in the urine the animal
produces.
Urine Production
in Different Environments
Comparison:
Marine Fish
problem: constant loss of water by osmosis.
urine: small amount, to conserve water.
Urine does not contain wastes, since ammonia is
excreted from the gills.
Freshwater Fish
problem: constant gain of water by osmosis.
urine: large volume, to remove water.
Urine does not contain wastes, since ammonia is
excreted from the gills.
Water Conservation &
Excretion in Insects
All insects are small, and most are adapted for
flight. This means they cannot afford to carry large
amounts of water in their bodies just for the
purpose of excreting urine. Their excretory system
must be able to remove nitrogenous wastes, while
losing only a minimum of water.
Firstly, their nitrogenous wastes are processed
chemically into the form of uric acid, which has a
low solubility in water. This means that, when their
urine is separated from the blood (filtration) and
then concentrated by reabsorption of water, the
uric acid precipitates as a solid.
After further reabsorption of water, the insect’s
urine is a semi-solid paste, which is passed into
the rectum and excreted with their solid digestive
wastes.
The Malpighian Tubes are the
insect equivalent of kidneys
Intestine
Terrestrial Mammal
problem: must excrete wastes in urine, but cannot
afford to lose too much water, especially in dry
Australian ecosystems.
urine: generally small volume, to conserve water.
Urine is relatively highly concentrated in wastes
such as urea.
ANUS
MOUTH
MALPIGHIAN TUBES extend through insect’s
body, collecting and concentrating urine.
Urine is emptied into the gut for excretion.
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Water Conservation & Excretion in Australian Mammals
They achieve this by:
Many Australian environments are
desert or semi-arid and water
conservation is vital for survival.
Some adaptations for temperature
control, while conserving water,
were covered earlier in this topic.
Many Australian mammals have
excretory systems that also
contribute to water conservation,
while managing to efficiently
remove their nitrogenous waste, urea.
The desert-living Red Kangaroo, the
Spinifex Hopping Mouse, and even the
Koala (which rarely drinks) all have the
ability to produce very small amounts of
highly concentrated urine.
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• having longer tubules in
their kidney nephrons,
which allows for more
reabsorption of water back
into the blood, thus less
urine is produced.
• the cells lining the
tubules are able to
actively transport urea from blood into
the urine. So, not only is urea not
reabsorbed from the “filtrate” liquid, but is
actively “pumped” from the blood.
The result is less water and more urea in
their urine.
Page 23
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Enantiostasis
Enantiostasis is a special case of homeostasis.
It refers to the maintenence of metabolic and physiological functions, (i.e. homeostasis)
despite significant variations in the surrounding environment.
keep it simple science
An important example is an estuary,
where river meets sea. Organisms are
able to maintain their water and salt
balance, despite wild fluctuations in
the water and salt concentrations
around them, every time the tides
change.
Examples of how they do this are:
Crabs & yabbies burrow into the mud, where the salt
concentrations are more stable.
Oysters close their shell, to avoid extreme conditions they
cannot cope with.
Estuary fish, like bream, switch their excretory systems
from water conservers when it’s salty, to water excreters
when it’s fresh.
Water Conservation in Australian Plants
The characteristics of Australia’s sclerophyll plants
were dealt with in the Preliminary Course topic
“Evolution of Australian Biota”.
In summary, the sclerophyll plants include the gum
trees, banksias and acacias (wattles) and all show
numerous adaptations to conserve water in our arid
climate, such as:
• Small, narrow, drooping leaves with thick, waxy
cuticles.
• In dry times, gum trees shed many of their leaves
so that there are less surfaces for evaporation.
• Species such as Spinifex grass limit evaporation
by having fine hairs all over their leaves. This traps
a layer of air near the leaf so that wind cannot
increase evaporation rates.
• Generally, all Australian sclerophylls have fewer
stomates on their leaves to limit the water loss from
transpiration.
GUM
LEAVES
Small & narrow to
reduce Surface Area
for less evaporation
How Plants Cope With Salt
Many of the Australian coastal estuaries are home
to Mangrove trees which have a number of
adaptations to cope with the salt water that covers
their roots with every high tide.
To maintain
their
“osmotic
balance”
they must
both
conserve
water and
deal with
high levels
of salt.
Mangroves in
coastal NSW
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One of the
most
common
species is
the “Grey
Mangrove”,
Avicennia
marina, which has all the following adaptations:
• Leaves with a thick, waxy cuticle and fine hairs
on the undersurface, all to minimise water loss.
• Salt glands in the leaves which excrete a
concentrated salt brine onto the leaf surface. The
salt gets washed away when it rains.
Thick, waxy
cuticle
minimises
evaporation
Droop downwards to avoid the heat of
midday for less evaporation
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• Salt is deposited in older leaves, so when they
drop off they carry a load of excess salt away.
• Special tissues within their roots which allows
water to pass through, but reduces the passage of
salt. This helps to reduce the salt intake.
Page 24
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Complete Worksheets 11,12,13 & 14.
KISS Resources for the NSW Syllabus.
®
keep it simple science
Worksheet 1
Enzymes & Homeostasis
Fill in the blank spaces.
The total of all the chemical reactions in an
organism’s body is called a)........................................
Each reaction requires a catalyst, which is a
chemical which b).................................... the reaction,
without being c)............................................... itself.
Biological catalysts are called d).................................
These have the following properties:
They are molecules of e)................................., which
are polymers of f)...................... .........................
Each one has its own unique g).................................,
which perfectly fits the molecule(s) of the reaction.
These molecules are referred to as the
h)..................................... Because each enzyme only
fits its own particular h)..............................., they are
said to be i)....................................................
Enzymes will only work effectively in a narrow
range of j).................................. and k)....................
This is because their l).................................. changes
so that they no longer fit their substrate.
The pH scale is a numerical measurement of
m)........................ and n)........................................
Things that are neutral have a pH= o)............. Acids
have pH values p).................... 7, while alkalis
(bases) have pH q)..........................
Worksheet 2
Name....................................
The pH inside living cells, and in most parts of an
organism’s body is about r).............., but an
exception is the s)............................... which is quite
strongly t).....................................
Homeostasis is the process of keeping an
organism’s internal environment u)...........................
The factors that need to be maintained include
v).................................. and w)................ as well as
x)............................. and salt balance,
y).......................................... levels and oxygen and
carbon dioxide levels.
Homeostasis involves z)........................ feedback.
The 3 parts of any feedback system are the
aa)..........................., which measures or monitors
conditions, the ab)........................................ which
decides how to respond and issues commands,
and the ac).................................... which carry out
the commands.
In animals generally it is the
ad).......................................... system which is
largely responsible for monitoring and control. In
mammals, homeostasis of body temperature is
controlled by the ae)........................................... at
the base of the af).................................
Enzyme Activity Graphs Name....................................
1. Sketch the shape of a graph of
Enzyme Activity against Temperature.
3. Sketch a graph of Enzyme activity against pH.
4. Explain why the graph
shows a “peak” of
optimum activity
at a certain pH.
5. Why does activity decline at pH values higher or lower
than the optimum?
6. Sketch a graph of enzyme activity against substrate
concentration.
2. Explain the shape of the graph;
7. Explain
a) at temperatures below the “optimum a) why the graph rises
b) at temperatures above the optimum.
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b) why the graph
levels off
Page 25
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KISS Resources for the NSW Syllabus.
Worksheet 3
Test Questions
®
keep it simple science
Multiple Choice
1.
Which of the following is NOT true about enzymes?
Enzymes:A. are catalysts which speed up chemical reactions.
B. are carbohydrate molecules of a special shape.
C. only work within a narrow range of temperature.
D. only works for one substrate... “specific”.
3.
At point D on this graph, you
could describe the enzyme
as:
A. saturated with substrate.
B. optimum shape.
C. decomposed.
D. denatured.
Name....................................
6.
The effect on enzyme activity of increasing the
substrate concentration is best described as:
A. Activity rises to an “optimum”, then declines.
B. Activity always continues to rise.
C. Activity declines as concentration increases.
D. Activity rises, then levels off.
Longer Response Questions
Mark values given are suggestions only, and are to give
you an idea of how detailed an answer is appropriate.
Answer on reverse if insufficient space.
7. (4 marks)
Discuss the importance of shape to the
characteristics of an enzyme, with specific
reference to:
a) why each enzyme will usually only catalyse only
one reaction.
D
Temperature
Enzyme Q
Enzyme P
Enzyme Activity
4.
This graph
compares the
performance
of 2 enzymes
at different pH
levels.
Rate of reaction
The graph shows the rate of an enzyme-catalysed
reaction.
Questions 2 and 3 refer to it.
B
2. Which part of this graph
(A,B,C or D) corresponds to
C
the enzyme having the best
3-dimentional shape to fit its
substrate?
A
section 1
b) why enzymes only work within fairly narrow
ranges of temperature and pH.
8. (8 marks)
The following data was collected in an experiment
in which the time taken for a chemical reaction
catalyzed by an enzyme, was measured at different
temperatures.
o
Temp ( C) Time taken for reaction (min.)
5
4.0
10
2.0
15
1.0
20
0.2
25
2.5
30
10
a) Tabulate this data appropriately, adding a third
column for “Reaction Rate” and calculating values
for this.
1 2 3 4 5 6 7 8 9 10
pH
b) Construct a graph of Temperature v Rate.
It would be reasonable to conclude that:
A. “P” is a stomach enzyme, “Q” is intra-cellular.
B. “P” is from a plant cell, “Q” is from a mammal
cell.
C. “Q” performs better than “P” under all
conditions.
o
D. Both would have optimum activity at about 40 C.
c) Is it likely that this is a human enzyme? Explain.
5.
Which of the following is least likely to be
controlled by a negative feedback system?
A. Body temperature
B. Blood sugar levels
C. Rate of digestion
D. Water & salt
INSPECTION COPY
levels.
b) What is the link between the necessity for
homeostasis and enzymes?
9. (5 marks)
a) What is meant by “Homeostasis”
c) Using a simple example, explain the concept of
“negative feedback” as a way to maintain stability
of any system.
for schools only
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Worksheet 4
Temperature Regulation
Fill in the blank spaces.
Temperature regulation in mammals is
controlled by the a)..................................... at
the base of the brain. If body temperature is
too high it sends commands to the
b)..................................... organs to cool the
body. Cooling mechanisms include
c)............................ of blood vessels to allow
d)................... (more/less) blood to flow near
skin. Also, the e)............................ glands
may be activated, allowing f).........................
to flow. As it g).............................. from the
skin, it carries heat away. Metabolic rate
may be reduced, to reduce heat production.
This is achieved by h).......................... which
are control chemicals. An example is
Thyroxine, produced by the
i)....................................... gland.
If the body is too cool, then the
hypothalamus commands various warming
mechanisms. Blood vessels can be
j).................................... to reduce blood flow
to k)......................
Body hairs are
l).............................. to trap a layer of still air,
which acts to m).................................. better.
Nerve commands to muscles can cause
them to n)............................. which produces
extra heat. The metabolic rate can be raised
by hormones as well.
Animals which rely on the environment to
supply their body heat are called
o)........................................ Examples are
p)............................, amphibians, fish etc. In
terrestrial environments they often seek or
avoid the heat of the q)................ in order to
regulate temperature. An Australian
example is the r)............................, which
often s)......................... in the morning to
warm up, and t)..................................... when
too hot. In cold winters, ectotherms cannot
get any heat from the environment and
many, such as the u).....................................
survive by v)................................. for the
winter.
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Name....................................
Animals which can regulate their body
temperature are called w)..............................
Examples are the x)......................... and
y).................. They use all the homeostasis
techniques, plus rely on body insulation
with fur, z).................... or aa).....................
In extreme environments endotherms may
have extra adaptations. In Australian
deserts many animals have large
ab).................... to radiate heat away. They
don’t have sweat glands because they
can’t afford to ac)..........................................
but may lick their ad)............................... or
pant to achieve some evaporative cooling.
In cold environments, thick fur or blubber
gives ae)...................................... to retain
body heat. The penguins have a special
adaptation in the blood vessels to their
legs. In cold water, the blood flow to the
feet is af).................. ......................................
so that less heat is lost through the
uninsulated feet.
Plants also have many adaptations to cope
with temperature extremes. In cold
climates many plants are
ag).............................. which means they
ah)............................................ in winter.
In hot climates with plenty of water, plants
open their ai)............................ allowing
evaporation to cool them. In dry climates,
plants cannot afford the water loss, so
they stay cool without losing water. For
example, cacti have aj).......................shaped leaves to reduce the surface area
absorbing heat from direct sunlight. They
are often ak)...........................-coloured to
reflect heat radiation.
The Australian al)...................................
plants mostly have am)..................................
(shape) leaves to reduce surface area, and
often allow the leaves to an).........................
(orientation) to avoid the Sun’s heat at
midday.
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®
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Worksheet 5
Test Questions
Multiple Choice
1.
The “control centre” for homeostasis
involving the nerve system is the:
A. Hypothalamus
B. Cerebrum
C. Cerebellum
D. Pituitary gland
2.
Which of the following is a response by an
effector organ which would be appropriate
when the body is too warm?
A. Muscles begin shivering.
B. Blood vessels dilated.
C. Body hairs erected, forming “goose
bumps”.
D. Metabolic rate increased by a hormone.
3.
Which statement is correct?
A. Ectotherms such as fish, generate their
own body heat.
B. Endotherms such as birds, rely on their
surroundings to supply their body heat.
C. Ectotherms such as mammals,
generate their own body heat.
D. Ectotherms such as reptiles, rely on
the surroundings to supply body heat.
4.
A typical response of an ectotherm to
over-heating is:
A. sweating
B. sun-baking
C. seeking shade D. shivering
section 2
Longer Response Questions
6. (8 marks)
a) Discribe the role of the hypothalamus in the
regulation of body temperature in a mammal.
b) Give an outline of how the blood vessels
function as “effectors” in the regulation of body
temperature.
c) List 3 other effectors (apart from blood vessels)
involved in temperature regulation.
7. (6 marks)
a) Explain the difference between an ectotherm and
an endotherm.
b) Using a named Australian example, outline how
an ectotherm regulates its body temperature.
c) Using a named Australian example, outline 2
adaptations of desert-living endotherm to keep
their bodies cool.
5.
An important adaptation in Australian
mammals to help keep cool in a desert
environment is:
A. a lot of sweat glands in the skin.
B. a “stocky”, thick-set shape to minimise
heat absorption.
C. large ears to acts as heat radiators.
D. thick fat layers to prevent heat getting
into their body.
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Name....................................
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8. (3 marks)
Describe some adaptations of sclerophyll plants
which help them minimise absorption of heat from
the Sun.
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keep it simple science
Worksheet 6
Transport in Animals
Fill in the blank spaces.
Blood is made up mainly of a liquid called
a).......................... and many blood cells.
The most numerous blood cells are the
b)........................... which contain the protein
c)............................. responsible for carrying
d).............................. gas. Most of the carbon
dioxide in blood is carried in the form of
e).................................... ions. These are
made when carbon dioxide reacts with
f)................. forming g)........................ acid.
Most other substances carried in blood are
dissolved in the h)................................. This
includes nutrients such as i).........................
and j)................................., water and salts,
and the nitrogenous waste k).........................
Lipids (fats) are first wrapped in a coating
of l)............................ so they can be
dispersed without separating.
There are 3 types of blood vessels: the
m)................................... have thick muscular
walls to withstand the high n)......................
of the blood being pumped from the
o)..................................
Worksheet 7
Name....................................
p)................................ have thinner walls, and
have q)................... along their length to
prevent blood r)..................... ............................
Capillaries have walls which are
s).................................. thick and form a network throughout the body’s t).........................
As the blood flows around the intestines it
picks up u)..................................... It then
flows straight to the v)................................,
where some nutrients are removed for
w)....................... & ............................, and
wastes such as x)..........................are added.
These wastes are later removed from the
blood by the y).................................. and
excreted with any excess z)........................ &
...................... as urine.
Meanwhile, when blood flows through the
capillaries of the lungs, aa)...........................
gas is absorbed into the blood and
ab).............................. gas is released from
blood into air. When blood flows through
the body tissues, nutrients move from
ac)........................ to ad).................................
as does ae)............................... gas, while
af)..................................... gas moves the
other way.
Blood Chemistry
Name....................................
Answer the following questions.
1. Write 2 chemical equations to
summarise how carbon dioxide reacts
with water.
3. With reference to one of the equations in
Q1, explain why it is essential to quickly
remove CO2 from body tissues.
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4. With reference to one of the equations in
Q1, explain how the oxygen release from
blood cells to body tissues is facilitated.
2. Name the chemical form in which most
CO2 is carried in the blood.
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Name....................................
Worksheet 8
Haemoglobin & Blood Products
Fill in the blank spaces.
Oxygen is carried by the a)...............coloured, b).....................-containing protein
called c)....................................... It has a
great affinity for oxygen molecules, and
each molecule can absorb d).............
(number) oxygen molecules, in which form
it is called e)..............- ....................................
Most blood donated to the “Blood Bank” is
separated into different fractions for
different uses. Some of the main blood
products are:
n)..................... Cell Concentrate, to boost
O2-carrying capacity.
White Cell Concentrate, to boost
o)..............................
In the body tissues, the presence of
f).................................... gas lowers the pH
slightly, which causes haemoglobin to
change shape slightly and g).........................
the oxygen, which then h).............................
into the cells.
p).......................... Concentrate, to help
blood clotting.
The “%SpO2” is a measure of the
i)........................................... in a person’s
blood. Good health, fitness and adequate
oxygen supply are indicated by readings
above j)..............% This can be easily
measured by a k).........................................
which sends beams of l)..................... &
...................... through a finger or ear-lobe.
Oxygen saturation is measured according
to how much of each type of light is
m)....................................... by the blood.
Research is going on into developing
artificial blood. This is needed because
fresh blood cannot be s)......................... for
long, and can cause t).................................
in some patients, There is also a danger
that donated blood might carry
u)...............................
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Worksheet 9
q)....................., which is the liquid part of
the blood, used in emergency to increase
r).........................................
Two of the areas of research for artificial
blood are: v).......................... -Based
w)..................... Carriers, made from animal
blood, and completely artificial substitutes
based on the chemicals called
x)......................................................
Transport in Plants
Fill in the blank spaces.
Transport in plants is carried out by 2
separate systems. The a)...........................
tubes carry water and dissolved minerals
from the b)..................... to c)........................
These tubes are d).............................. (dead
or living) cells. The transport is
e)................................. (active or passive)
and the movement of water is called
f)................................................. Basically
the process works because, as water
g)..................................... from the leaves,
this “pulls” water up from above
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Name....................................
because water molecules are
h)............................. and cling together.
Meanwhile, the i).....................................
vessels carry out j).......................................
(name of process) which moves
k)................................................ around the
plant to wherever it is needed.
The cells are l)..................................... (dead or
living) and the transport is
m).........................................(active/passive)
requiring the plant to
n)......................................................... in order
to make the process happen.
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KISS Resources for the NSW Syllabus.
Worksheet 10
keep it simple science Test Questions
Multiple Choice
®
1.
A blood vessel with relatively thin muscle layer and
equipped with one-way valves is most likely a:
A. Vein
B. Arteriole
C. Artery
D. Capillary
2.
As blood flows through a capillary in an active
muscle, you would expect changes in the
substances carried in the blood, as follows:
A.
B.
C.
D.
Increase in CO2, decrease in O2 and sugars.
Decrease in CO2 and sugars, increase in O2
Inrease in CO2 and sugars, decrease in O2
Decrease in CO2 and O2, decrease in sugars
3.
Which line correctly identifies the way in which
most of the oxygen and carbon dioxide gases are
carried in the blood?
Oxygen
A. dissolved in plasma,
B. in haemoglobin,
C. in white cells,
D. in haemoglobin,
Carbon Dioxide
in haemoglobin
dissolved bicarbonate ion
in haemoglobin
dissolved carbonic acid
4.
The “Oximeter” is able to measure percentage
oxygen saturation of the blood because, depending
on the amount of oxygen present:
A.
B.
C.
D.
the blood pH changes
the ratio of red and white cells changes
the blood flows at a different rate
haemoglobin absorbs light differently
5.
Which statement about plant transport systems is
correct?
section 3
Name....................................
Longer Response Questions
6. (5 marks)
Describe the structural difference(s) of veins and
arteries, and relate these differences to the
functions of these blood vessels.
INSPECTION COPY
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7. (9 marks)
a) Contrast the way(s) that the gases oxygen and
carbon dioxide are carried in the blood.
b) These gases are described as the “respiratory
gases” because of their involvement in cellular
respiration. Summarise this process with a
chemical equation.
c) How is the release of oxygen from the
bloodstream facilitated by the high concentration
of carbon dioxide in the body tissues?
8. (4 marks)
Identify 2 of the “blood products” extracted from
donate blood, and describe the uses of these
products.
9. (6 marks)
Construct a table to contrast the processes of
Transpiration and Translocation in plants. Your
answer should cover:
• the name and nature of the vessels involved.
• the substance(s) transported.
• the basic nature of the processes.
A. Xylem use active transport for Transpiration.
B. Xylem cells are alive and do Translocation.
C. Phloem uses active transport to move
nutrients.
D. Phloem tubes carry out Transpiration
by passive means.
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Worksheet 11
Excretion & Water Balance
Fill in the blanks.
Water is vital to all living things because:
1. It is the a)......................... of life, and
most substances in a cell are b)..................
in water.
2. Water is involved in many
c)........................ reactions, such as
photosynthesis or d)................................
3. Water has very high “heat
e)......................................” and “heat of
f)....................................” so it is vital to
temperature control.
4. Water g)............................ and cushions
cells and organs. For example, plants rely
on water in cell h)........................... to keep
leaves and stems upright.
Name....................................
Maintaining the correct balance of both
water and dissolved i).......................... is
another aspect of j)...................................
In vertebrate animals, the control of water
balance is done by the k)...........................,
which also are responsible for excretion of
l)............................. wastes.
Different animals produce different wastes:
the fish produce mainly m)...........................
while birds and insects produce
n)........................... and mammals produce
o).........................
In fish, the kidneys are used mainly for
p)........................ because excretion of the
ammonia takes place from their
q)................................
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Worksheet 12
Water Balance in Plants & Animals
Name....................................
Fill in the blanks
Insects process their nitrogenous wastes
into the chemical a).........................................
which has very low solubility. This allows
them to excrete “urine” which is almost
entirely b)...........................
A good example is the way that estuarine
animals can maintain
j)...................................... balance despite
the fluctuations in salt concentrations as
the k)......................... change.
Many Australian mammals excrete very
c)........................ (small/large) amounts of
d)....................... (dilute/concentrated) urine.
They achieve this by having increased
ability to reabsorb e)...............................
from the nephron tubules, and can
f)................................. (actively/passively)
pump urea from g)............................. into the
h)...................................
Mangrove plants deal with salt by special
root tissue to l).............................. its entry,
or by m).................................. salt onto their
leaves, or by n).......................... salt in older
leaves which are later shed.
When an organism can maintain
homeostasis despite significant variations
in the environment, this is called
i)..........................................
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Many Australian plants are well-adapted to
conserve water by such features as leaves
which are o)...................................... (shape
& size) and are covered with a thick, waxy
p)........................... They often have fewer
q)......................... on their leaves, or may
be covered with r)..................... to trap a
layer of air.
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Worksheet 13
Kidney Function
Fill in the blanks.
Each kidney contains about 1 million units
called a)............................ There is a coiled
blood vessel, the b).......................................
which is inside the c)..............................
capsule. Here the process of
d)............................ takes place, where
water and many dissolved substances
leave the blood and flow throught the
e)..........................................
The second process is f)..............................
in which any useful substances (most of
the water, plus g)....................... and
...........................) are absorbed back into
the h)........................... by a combination of
active transport and i).................................
Some water plus the j).................... are not
reabsorbed but pass into a
k)................................. duct, and down the
l).......................... to the bladder to await
excretion.
The kidneys also have a role in
m)...................................... by adjusting the
amounts of water and n)..............................
that are reabsorbed into the blood.
This function is controlled by the
o)..................................... which monitors
“water balance” and controls the release
of the hormone p).......................... from the
q)................................... gland.
This hormone increases the permeability
of membranes in the r)...............................
so that s)............... (more/less) water will
be absorbed, and t).............................
(more/less) urine formed.
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Name....................................
So, an increase in ADH secretion leads to
greater u)...........................................
(excretion/retention) of water, while a
decrease in ADH results in
v)................................ (more/less) urine
production.
Another hormone called
w).......................................... is produced by
the x).......................................... glands
controls the reabsorption of
y).................................. Some people do
not produce enough of this hormone and
so have a chronic salt-balance problem
called z)................................. Disease. This
disease is treated by
aa)......................................... Therapy (HRT).
If a person’s kidneys fail, they can have
their blood “cleaned” of wastes by the
process of “Renal ab)...................................
This is similar to kidney function in that
both involve movement of dissolved
chemicals through ac).................................
membranes. It is different from kidney
function in that it involves only ad)............
(number) process, which involves
ae)...................................... (active/passive)
diffusion. Kidney function has
af)............................ (number) steps, and
involves both ag).......................................
(active/passive) transport and osmosis.
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Worksheet 14
Test Questions
Multiple Choice
1.
A freshwater fish:
A.
B.
C.
D.
produces a large volume of dilute urine.
produces a small volume of concentrated urine.
excretes urea in large amounts via the kidneys.
excretes water from its gills and must
drink to replace it.
2.
In the mammalian kidney nephrons the formation
of urine occurs in 2 stages. Which line describes
correctly the location of each process?
A.
B.
C.
D.
Filtration
Glomerulus
Renal tubules
Glomerulus
Bowman’s capsule
Reabsorption
Bowman’s capsule
Ureter
Renal tubules
Collecting duct
Name....................................
section 4
6. (4 marks)
Outline the processes of Filtration and
Reabsorption in the nephron of a mammalian
kidney. Identify where each process occurs and the
main events occurring.
7. (6 marks)
Compare and contrast the role of the hormones
“ADH” and “Aldosterone” in the maintenence of
mammal homeostasis. Your answer should include
• source of each hormone
• precise effect on the target organ
• how this contributes to Homeostasis
3.
An increase in the level of the hormone “ADH”
would cause the kidney nephrons to:
A.
B.
C.
D.
reabsorb
reabsorb
reabsorb
reabsorb
less salt.
more water.
more salt.
less water.
8. (5 marks)
a) Outline the process of excretion of nitrogenous
wastes in insects, explaining how it contributes to
conservation of water in their bodies.
4.
Insects conserve water by excreting their
nitrogenous wastes in the form of:
A. a semi-solid paste of uric acid.
B. a small volume of urine, highly concentrated
in urea.
C. a large amount of ammonia-containing urine.
D. pellets of solid urea.
b) Using a named example of an Australian
mammal, explain how the excretion of nitrogenous
wastes is achieved with minimum water loss.
Longer Response Questions
Use reverse if insufficient space.
5. (4 marks)
Discuss briefly the importance of water in living
organisms, identifying 4 functions of water.
INSPECTION COPY
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9. (8 marks)
a) What is “Enantiostasis”? Give an example of an
environment where this process is vital and outline
some of the strategies for achieving enantiostasis
in the named environment.
b) Identify strategies for conservating water in 2
named Australian plants.
c) Describe 2 strategies used by mangrove trees to
maintain water balance in a saline environment.
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Worksheet 3
2.a) reaction rate (=activity)
increases as temp. goes up
because molecules are more
likely to collide and react with
each other.
Temp
2. B
3. D
4. A
5. C
6. D
7.
a) Enzymes are protein molecules and each has a a
particular 3-dimensional shape which fits its
substrate like a key fits a lock. Usually each
enzyme will only “fit” one particular substrate, so it
will only catalyse one reaction.
b) Any change in temperature or pH can change
the shape of an enzyme, by causing the protein
chain to alter the way it is folded and twisted. As
its shape changes, its ability to “fit” the substrate
will change too. Thus each enzyme only works
fully within relatively narrow ranges of temperature
and pH.
8.
a) Table should be ruled and have clear headings.
The values in the 3rd column should be:
-1
Reaction Rate (min ) Reaction Rate v Temp. Graph
0.25
0.5
1.0
5.0
0.4
0.1
5
1. graph
Activity
Worksheet 2
1. B
4
a) metabolism
b) speeds up
c) used up / consumed
d)enzymes
e) protein
f) amino acids
g) 3-dimensional shape
h) substrate(s)
i) specific
j) & k) temperature & pH
l) shape
m) & n) acidity & alkalinity
o) 7
p) below
q) above 7
r) 7 / neutral
s) stomach
t) acidic
u) stable / at the same level
v) temperature
w) pH
x) water
y) blood sugar
z) negative
aa) receptor
ab) control centre
ac) effectors
ad) nervous
ae) hypothalamus
af) brain
Reaction Rate (1/min)
Worksheet 1
3. graph
c) No.
0
5
10
15
20
25
30
The graph shows
o
that at human
Temperature ( C)
body temp. (37C)
the enzyme’s activity is almost zero. This enzyme
would NOT function in a human body.
4. At the optimum pH the shape
of the enzyme is a perfect “lock
& key” shape to fit the
substrate, so activity is at a
maximum.
pH
5. At pH’s either side of optimum the shape of the
enzyme changes so that the “fit” with the substrate
is no longer perfect, so activity declines.
Activity
6. graph
7. a) As the
concentration of
substrate molecules
increases, it becomes
more likely that they will
Substrate concentration
collide with an enzyme
and undergo the
reaction. So reaction rate increases.
b) However, once all the available enzyme
molecules are being used, (they are “saturated”
with substrate) increasing the concentration
cannot increase reaction rate any further, so the
graph levels off.
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2
1
b) graph
3
(These values
are calulated as
1/time taken)
Activity
b) Above the optimum the shape of the enzyme
protein begins to change and be distorted. The
substrate(s) no longer fit the enzyme perfectly, and
activity declines rapidly.
9.
a) Homeostasis is the process of maintaining a
stable, internal environment, for such things as
temperature, pH, water balance, etc.
b) Homeostasis is vital so that the optimum
conditions (of temp., pH etc) for enzymes to
function efficiently are maintained. Efficient
enzyme activity is essential so that the reactions of
metabolism occur at a rate appropriate for life
functions.
c) example: thermostat control of an oven
A temperature sensor constantly monitors the
temp. If oven is too cool, the control mechanism
sends an electrical signal to turn the heating
element on. (effector)
If the oven is too hot, a signal is sent to turn the
heating element off, so the oven will cool down.
By always taking action in the opposite direction
(negative feedback) a relatively stable temperature
is maintained.
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Worksheet 4
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a) hypothalamus
b) effector
c) dilation
d) more
e) sweat
f) perspiration
g) evaporates
h) hormones
i) thyroid
j) constricted
k) the skin
l) raised / erected
m) insulate
n) shiver
o) ectotherms
p) reptiles
q) Sun
r) Blue-tongue lizard
s) sunbakes
t) seeks shade
u) copperhead snake / corroboree frog
v) becoming dormant w) endotherms
x) & y) mammals & birds
z) feathers
aa) blubber (fat)
ab) ears
ac) lose water
ad) fore arms
ae) insulation
af) shunted back into the body
ag) deciduous
ah) shed their leaves
ai) stomates
aj) needle / spine
ak) light
al) sclerophyll
am) narrow
an) droop downwards
Worksheet 5
1. A
2. B
3. D
4. C
5. C
6.
a) The hypothalamus is both the receptor and
control centre for regulation of temperature.
Blood flowing through the hypothalamus is
constantly monitored by heat-sensitive cells. If
body temperature is even slightly high or low, the
hypothalamus sends nerve messages to various
effector organs to either warm or cool the body
back to its correct temperature.
7.
c) Desert-living endotherms, such as the Bilby,
cannot afford the water loss involved with
sweating to cool off. Instead, they have large ears
to radiate heat away. They seek shade in the heat
of the day and are active only in the evenings and
early morning. Instead of sweating, they “pant” so
that evaporation from the mouth and throat has a
cooling effect.
8.
Sclerophyll plants have
• small, narrow leaves to reduce surface area
exposed to Sun.
• shiny leaf cuticle to reflect some radiant heat
• leaves which “droop” downwards. This allows for
absorption of light for photosynthesis in the cool
of the morning, but avoids heat absorption in the
heat of midday.
Worksheet 6
a) plasma
b) red
c) haemoglobin
d) oxygen
e) bicarbonate
f) water
g) carbonic
h) plasma
i) sugars
j) amino acids
k) urea
l) protein
m) arteries
n) pressure
o) heart
p) Veins
q) valves
r) flowing backwards
s) one cell
t) tissues
u) digested nutrients v) liver
w) processing & storage
x) urea
y) kidneys
z) water & salts
aa) oxygen
ab) carbon dioxide
ac) blood
ad) cells
ae) oxygen
af) carbon dioxide
b) Veins and arteries can be constricted (narrowed)
to reduce the blood flow to the skin. This reduces
the amount of heat lost through the skin, thereby
helping to warm the body. The opposite process of
dilating (widening) the blood vessels allows more
blood flow to the skin. This allows more heat to be
lost from the skin, thereby cooling the body.
Worksheet 7
c) Three other effector organs:
Sweat glands (perspiration), skeletal muscles
(shivering), thyroid gland (hormone thyroxine),
body hair muscles (goose bumps).
2. CO2 is mostly carried as bicarbonate ion.
7.
a) Endotherms are animals which generate their
own body heat.
Ectotherms rely on their environment to supply
their body heat; they do not generate internal body
heat.
b) Ectotherms such are the Blue-Tongue Lizard
often use instinctive behaviours to regulate
temperature. When too cold, it will sunbake,
flattening its body to increase the surface area
exposed to the Sun. When too hot, it will seek
shade and avoid the heat of the Sun.
Biology 9.2 “Maintaining a Balance” PhotoMaster
copyright © 2014 KEEP IT SIMPLE SCIENCE
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1. CO2 reacts with water to form carbonic acid
CO2 + H2O
H2CO3
Carbonic is a weak acid which partly ionises
H2CO3
H+ + HCO3-
3. The equations show that carbon dioxide reacts
with water forming an acid. If allowed to
accumulate, this would lower the pH, which could
seriously affect the activity of enzymes and disrupt
metabolism.
4. As shown in the equations above, the presence
of carbon dioxide lowers the pH. In tissue
capillaries, the slightly lowered pH alters the shape
of the haemoglobin molecules slightly. This
causes them to release the oxygen molecules they
are carrying, which then diffuse into the cells.
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Worksheet 8
®
9.
keep it simple science
a) red
b) iron
c) haemoglobin
d) 4
e) oxyhaemoglobin
f) carbon dioxide
g) release
h) diffuse
i) percent oxygen saturation
j) 95%
k) Oximeter
l) red light & infra-red light
m) absorbed
n) Red
o) immunity
p) Platelet
q) Plasma
r) blood volume
s) stored
t) immune-responses
u) diseases
v) Haemoglobin
w) Oxygen
x) Perfluorocarbons
Worksheet 9
a) xylem
c) leaves
e) passive
g) evaporates
i) phloem
k) nutrients / sugars
m) active
b) roots
d) dead
f) transpiration
h) cohesive
j) translocation
l) alive
n) use energy
Transpiration
Vessels
involved
Xylem
(dead cells)
Substances
transported
Water &
minerals
Processes
involved
Passive
transport
2. A
3. B
4. D
5. C
6.
Arteries have thick, muscular walls. This allows
them to withstand the high pressure blood they
carry as the heart pumps. Being elastic, the walls
can expand outwards under pressure, then
contract and help squeeze the blood on its way.
Veins have thinner walls since the blood they carry
back to the heart is at low pressure. Veins are
equipped with valves to prevent back-flow. The thin
walls of a vein allow them to be compressed by
neighbouring muscles, which helps squeeze the
blood forward.
7.
a) Oxygen is carried attached to the haemoglobin
molecules in the red blood cells.
Most carbon dioxide is carried in solution in the
blood plasma as bicarbonate ion, HCO3-.
b) C6H12O6 + 6O2
6CO2 + 6H2O + ATP
c) The high concentration of dissolved CO2 causes
the pH to be slightly lower (because CO2 reacts
with water forming carbonic acid). This change in
pH causes a change in the shape of the
haemoglobin molecule, which causes it to release
oxygen, which can then diffuse into the
surrounding body cells.
8.
Red Cell Concentrate contains about 2x as many
red cells as normal blood. It is used to treat people
with severe anaemia, or following severe blood
loss.
Platelet Concentrate is given to patients who need
extra blood-clotting capability, such as leukemia
sufferers.
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Phloem
(living cells)
Nutrients,
especially
sugars
Active
transport
Worksheet 11
a) solvent
c) chemical
e) capacity
g) supports
i) salts
k) kidneys
m) ammonia
o) urea
q) gills
b) dissolved
d) metabolic / chemical
f) vaporisation
h) vacuoles
j) homeostasis
l) nitrogenous
n) uric acid
p) water balance
Worksheet 10
1. A
Translocation
Worksheet 12
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a) uric acid
b) solid / dry
c) small
d) concentrated
e) water
f) actively
g) blood
h) tubules / urine
i) enantiostasis
j) water & salt
k) tides
l) limit
m) secreting / excreting
n) storing / accumulating
o) small & narrow
p) cuticle
q) stomates
r) hairs
Worksheet 13
a) nephrons
b) glomerulus
c) Bowman’s
d) filtration
e) renal tubules
f) reabsorption
g) sugars / salts / amino acids
h) bloodstream
i) osmosis
j) urea
k) collecting
l) ureter
m) homeostasis
n) salt
o) hypothalamus
p) ADH
q) pituitary
r) renal tubules
s) more
t) less
u) retention
v) more
w) aldosterone
x) adrenal
y) salt
z) Addison’s
aa) Hormone Replacement
ab) Dialysis
ac) semi-permeable
ad) one
ae) passive
af) two
ag) active
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Worksheet 14
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1. A
2. C
3. B
4. A
5.
Water is the solvent of life
All the chemical reactions of metabolism take place
in water solution, and the transport of materials
takes place in water solution.
Water is involved in life chemistry
Water is a reactant or product of many metabolic
reactions.
Water is vital in temperature regulation
Water has a very high specific heat capacity. This
helps stabilize the temperature of all living things.
Evaporation of sweat is an important cooling
mechanism in mammals.
Water supports and cushions cells and organs
Water solutions in the tissues helps to cushion
organs against bumps and impacts.
(eg cerebrospinal fluid around the brain)
6.
Filtration occurs in the glomerulus. Some of the
water of the blood plasma and its dissolved
sugars, minerals, urea etc seep out of the blood
vessel, like water through a filter paper. Blood cells
and proteins cannot leak out.
This “filtrate” flows along the renal tubules where
reabsorption occurs. Useful nutients (sugars,
amino acids) are actively transported back into the
bloodstream. Most of the water in the filtrate flows
back to the blood by osmosis. A portion of the
water with dissolved urea flows on to be excreted
as urine.
7.
ADH is secreted by the pituitary gland (under
control of the hypothalamus) It alters the
permeability of the renal tubules to water.
Increased ADH allows greater water reabsorption,
and less urine production.
Aldosterone is secreted by the adrenal glands. It
stimulates the cells lining the renal tubules to
actively transport more sodium ions back into the
blood from the renal fitrate. This retains more salt
in the body to adjust “osmotic balance”.
8.
b) The Spinifex Hopping Mouse is a desert-dweller
which produces very small amounts of very
concentrated urine. This is achieved because:
• the nephron tubules are very long, allowing for
more reabsorption of water, and less volume of
urine.
• the cells lining the tubules are able to actively
transport urea from the blood into the urine. This
allows the urine to be even more highly
concentrated than in other mammals.
9.
a) Enantiostasis is a special case of homeostasis,
in which an organism maintains a stable internal
environment despite significant changes in the
environment around it. An example of a habitat
where this is important is a tidal estuary, where the
tides cause the salinity of the environment to
fluctuate.
To maintain their “osmotic balance” while their
evironment changes from virtual fresh water, to
salty and back again, requires estuarine organisms
to cope by strategies such as:
• burrowing into the mud where the salinity is
more constant. (eg crabs & yabbies)
• adjusting the functioning of their kidneys from
water excreters to water conservers as the tides
change. (eg fish)
b) Spinifex Grass has fine hairs all over its leaves.
This traps a layer of still air near the leaf, reducing
the evaporative effect of the wind.
Gum trees, such as the River Red Gum, has leaves
with very few stomates, and a thick, waxy cuticle
to minimize water losses.
c) Mangroves:
• secrete salty brine onto the leaf surface. This
washes away when it rains.
• accumulate salt in older leaves which are then
shed, carrying away a load of excess salt.
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8.
a) The insect equivalent of kidneys are the
“malphigian tubes” which run all though the body
and collect and concentrate nitrogenous wastes in
the form of uric acid. Since this is basically
insoluble, the “urine” can be concentrated to a
semi-solid paste by reabsorbing virtually all the
water, before passing the wastes into the rectum
for excretion with the digestive wastes. This means
there is virually no loss of water during excretion.
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