Maintaining a balance

9.2 Maintaining a Balance
• Most organisms are active in a limited
temperature range
• Plants and animals transport dissolved
nutrients and gases in a fluid medium
• Plants and animals regulate the
concentration of gases, water and
waste products of metabolism in cells
and in interstitial fluid

Identify the pH as a way of describing the acidity of
a substance

 pH is a the amount of hydrogen ions
measured in a substance (solution)
 pH of 7 is neutral e.g. water, 0-6 is
acidic .e.g. lemon juice, 8-14 is basic .e.g.
sodium bicarbonate

Explain why the maintenance of a constant internal
environment is important for optimal metabolic
efficiency

 Cells work best under their optimum conditions-
right pH, temperature and the best
concentration.
 Enzymes control all metabolic processes in the
body
 Enzymes work in an environment where they’re
optimum temperatures and pH conditions are
met. At temperatures and pH values other than
the optimum, the enzymes fail to work as
efficiently as they should or not at all.

Describe homeostasis as the process by which
organisms maintain a relatively stable internal
environment

 In order to maintain maximum efficiency of an
enzyme, the body must maintain a stable/
constant internal environment. This is known as
homeostasis.
 Homeostasis is the process by which the internal
environment is kept within normal limits
regardless, of the external environmental
conditions. This includes temperature, pH, gas
levels, water and salt concentrations. This allows
the enzyme’s optimal conditions to be met and
the body to work efficiently and kept stable

Explain that homeostasis consists of two stages:

 Detecting changes from the stable state
 Counteracting changes from the stable state
 Detecting changes-
 Receptors detect changes to the normal internal
environment. e.g. sensory neurons in the skin pick up a
decrease or increase in temperature of air surrounding
the body.
 Counteracting changes-
 After the receptors have detected these changes, action
is taken to counteract these so that homeostasis is
maintained. These are done by effectors. e.g. shivering
to generate heat in muscles.

Outline the role of the nervous system in detecting
and responding to environmental changes

 The co-ordinating system in humans is the nervous system.
 The nervous system consists of the central nervous system (CNS)
and the peripheral nervous system (PNS). The CNS consists of the
brain and spinal chord and the PNS consists of the sensory nerves
and the effector nerves. When the environmental temperature
begins to exceed a comfortable level for the body. The stimulus is
detected and the sensory neurons send an impulse to the brain
where the information is interpreted and a response is initiated. This
response is then sent to the effectors.
 Example- Temperature sensors in the skin detect the temperature
change (the stimuli) and a sensory neuron conducts a nervous
impulse to the hypothalamus found in the brain. Nerve impulses
pass this response from the receptors to effector neurons then onto
effectors, such as blood vessels, sweat glands, endocrine glands
and muscles. This is when we shiver to try and generate heat.
(counteract the stimuli)

Identify the broad range of temperatures over
which life is found compared with the narrow limits
for individual species

 Life forms can found in the temperature
range of –40ºC to 120ºC
 Majority of life forms are in the –2ºC to
40ºC temperature range and is narrower
for each individual species.
 Below 0ºC cell risk ice crystals forming
and above 45ºC causes them to denature.

Compare responses of named Australian ectothermic and
endothermic organisms to changes in the ambient
temperature and explain how these responses assist
temperature regulation

Endotherms
 Regulate body temperature using metabolism homeostasis. (birds
and mammals)
 Insulation- control of blood flow (capillaries dilate to keep you cool),
evaporation (humans sweat to keep cool), counter-current
exchange (blood vessels placed together and chilled bloody
returning from veins gets heated up) and metabolic activity (during
hotter weather metabolism slows down {by product of this HEAT})
are ways that endotherms control their body temperature.
 In hot conditions~ Example (1) Red kangaroo licks the inside of its
paws, where skin is thinner, and blood supply is closer to the
surface, so that heat can be easily dumped to the outside.
Evaporation from saliva promotes the loss of heat from the blood.
Example (2) The large ears of the rabbit-eared-bandicoot provide a
large surface area to pass excess heat when it is burrowing during
the heat of day and when it is active at dusk.

 Ectotherms-
 Body temperature fluctuates, according to ambient
temperatures. (reptiles)
 Hibernation- nocturnal activity, controlling exposure and
migration are ways that ectotherms control their body
temperature.
 In cold conditions~ Example (1) magnetic termites
(Amitermes meridionalis) pack the walls of their mounds
with insulating wood pulp and align their mounds north-
south to maximise exposure to the sun in the mornings
and the evenings when the air is cooler and to minimise
exposure during heat of day. Example (2) Bogong moths
are able to avoid their bodies freezing by supercooling their
tissues. This process involves reducing the temperature of
the body fluids below their usual point of freezing and as a
result, ice crystals do not form and destroy the cells.

 Characteristics of ectotherms and endotherms:
Behavioural adaptations:
 Migration
 Hibernation and aestivation
 Sheltering
 Nocturnal activity
 Controlling exposure

Structural adaptations:
 Insulation
 Physiological adaptations:
 Metabolic activity
 Control of blood flow
 Counter-current exchange
 Evaporation

Identify some responses of plants to temperature
change
 Plants can be damaged at temperature extremes when
enzyme structures are altered or membranes change
their proteins. As many enzymes are involved in
photosynthesis and respiration temperature extremes
can be a major problem.
 In cold conditions, extracellular ice formation causes
dehydration. Some plants can tolerate temperatures as
low as -50ºC by altering the solute concentrations and
through lack of ice-nucleating sites in cells to prevent
intracellular freezing.

 In hot desert conditions, plants develop a compromise
between access to gases for photosynthesis and access
to gases for respiration by keeping their stomates open
and cooling by evaporation. This risks dehydration.

 In hot or cold plants may die but leave dormant seeds
so to keep the flow going.
 They may die above the soil but leave their roots
embedded in the ground so that they can keep living
when conditions are good.
 Too high temperatures during flower formation may
cause poor crop
 Some seeds may only germinate after a fire.
 Example (1)- eucalyptus leaves grow vertically to reduce
exposure to the sun. Example (2)- porcupine grass-sand
in central Australia have curled leaves that opens up
after rain-exposing the stomata. In dry conditions the
leaf curls up, burying the stomata and reducing
transpiration ... conserving water.

Identify data sources, plan, choose equipment or resources and
perform a first-hand investigation to test the effect of:
Increased temperature
Change in pH
Change in substrate concentrations on the activity of named
enzyme(s)
FACTOR EFFECT ON ENZYME ACTIVITY

Increasing temperature Increases activity of the enzyme until it
denatures. They have an optimum
temperature.

Change in pH Depends on the enzyme. Each enzyme has
they’re own optimum pH and it may
denature.
Change in concentration The higher the concentration the faster the
of the substrate reaction rate. The rate of reaction is
limited by the amount on enzyme
present. (still works after saturation
point)

Lipase investigation Effect on temperature
 Aim: to determine the relationship the relationship between the
effect of temperature and the activity of the enzyme, lipase
 Hypothesis: the enzyme lipase works best at a temperature of
35-40ºC.
 Apparatus:
 Full fat milk
 8 test tubes
 Test tube rack
 5% lipase solution
 0.05M sodium bicarbonate solution
 Phenolphthalein
 Thermometer
 Large beaker with water
 Hot plate
 Measuring cylinders
 Stopwatch
 Pipettes

 Method:
 Place 50g of ice into a large beaker and test tubes 1 and 2 which
contain 1ml of milk in each test tube. Record the temperature.
 Then add 11mls of sodium bicarbonate solution and 5 drops of
phenolphthalein to each test tube.
 Add 1ml of lipase solution to test tube 1 and start timing. Note the
colour changes of the solutions at I minute intervals for 5 minutes
from the time of addition of Lipase. Note: test tubes 2,4,6 and 8 are
controls (.i.e. they don’t have the enzyme added to them.)
 Repeat steps 1-3 for test tubes 3 and 4 but this time use water at
room temperature approx. 20ºC
 Repeat steps 1-3 for test tubes 5 and 6 but this time use a water
bath set at 35ºC
 Repeat steps 1-3 for test tubes 7 and 8 but this time use a water
bath set at 50ºC
 Repeat steps 1-6 three times and average your results.
 Collate data in a table and graph format.

 N.B- for the experiment to be fair the following things are to be kept
constant:
 Lipase %: a higher lipase concentration will obviously speed up the
time it takes to break down the fat.
 Amount of milk/ lipase/ sodium bicarbonate/ water/ ice
 Use the same stopwatch for each test
 Repeat the experiment 3 times

Results:
Effect of temperature on the enzyme, lipase
Temp 0 1 2 3 4 5
Time
(mins):
Test tubes: (ºC)
1- 0 Deep Deep Deep Deep Deep Deep
Milky milky milky Milky Milky milky
pink pink pink pink pink pink

2- control 0 Deep Deep Deep Deep Deep Deep
milky milky milky milky milky milky

3- 20 Deep Deep Pale Lighter Lighter Lighter

4-control 20 Deep Deep Deep Deep Deep Deep

5- 35 Deep Pale Lighter Lighter Lighter White
pink pink pink pink pink

Milky milky milky milky milky milky

7- 50 Deep Deep Deep Deep Deep Deep


 Conclusion: the milk solutions turn white when the lipase
and milk come in contact to produce fatty acids. Sodium
bicarbonate makes the solution alkaline (pink) to start
with but as more acids are produced the pH drops and
the solution turns white. Lipase works best at a
temperature of 35ºC but beyond this denature, and
becomes inactive. Active sites of enzymes have a
particular shape and because of this only one substrate
molecule will fit into it. When an enzyme has lost its
shape because of heat, the shape of the active site
changes so a substrate molecule will no longer fit.

Substrate Concentration
 Aim: to determine the relationship the relationship between
substrate concentration and the effect of the enzyme, lipase
 Hypothesis: higher concentration milk will break down more
quickly into fatty acids by the action of the enzyme lipase.
 Apparatus:

Range of 3 different milk concentrations
 6 test tubes
 Test tube rack
 5% lipase solution
 0.05M sodium bicarbonate solution
 Phenolphthalein
 Large beaker
 Hot plate
 Measuring cylinders
 Stopwatch
 Pipettes

The different milks are:

Type of milk:

Test Tube 1 and 2 1ml full fat milk

Test Tube 3 and 4 0.5ml of full fat milk and 0.5ml water

Test Tube 5 and 6 0.25ml of full fat milk and 0.75ml water

 Method:
 Set up a water bath at 35ºC with test tubes 1 and 2
 Then add 11mls of sodium bicarbonate solution and 5
drops of phenolphthalein to each test tube.
 Add 1ml of lipase solution to test tube 1 and start
timing. Note the colour changes of the solutions at I
minute intervals for 5 minutes from the time of addition
of Lipase. Note: test tubes 2,4 and 6 are controls (.i.e.
they don’t have the enzyme added to them.)
 Repeat steps 1-3 for test tubes 3 and 4.
 Repeat steps 1-3 for test tubes 5 and 6.
 Repeat steps 1-5 three times and average your results.
 Collate data in a table and graph format.

 N.B- for the experiment to be fair the following things
are to be kept constant:
 Water bath at 37ºC
 Lipase %: a higher lipase concentration will obviously
speed up the time it takes to break down the fat.
 Amount of milk/ lipase/ sodium bicarbonate
 Use the same stopwatch for each test
 Repeat the experiment 3 times

Results:
Effect of temperature on the enzyme, lipase
Time (mins): 0 1 2 3 4 5
Test tubes:
1- high conc. of Deep Pale Lighter Lighter Lighter White
milk pin pin pink pink pink
k k
2- control Deep Deep Deep Deep Deep Deep
milk milk milky milky milky milky
y y pink pink pink pink
pin pin
k k
3- med. Con. of Deep Deep Pale pink Lighter Lighter Lighter
milk pin pin pink pink pink
k k

4-control Deep Deep Deep Deep Deep Deep
milky milky milky milky milky pink milky pink
pink pink pink pink

5- low conc. of Deep Deep Pale pink Pale pink Pale pink Pale pink
milk pink pink

6- control Deep Deep Deep Deep Deep Deep
milky milky milky milky milky pink milky pink
pink pink pink pink

 Conclusion: the milk solutions turn white when the lipase
and milk come in contact to produce fatty acids. Sodium
bicarbonate makes the solution alkaline (pink) to start
with but more acids are produced the pH drops and the
solution turns white. The results indicate that the higher
the concentration of the substrate milk, the quicker the
reaction of the enzyme, lipase.

Gather, process and analyse information from secondary
sources and use available evidence to develop a model of a
feedback mechanismSweatShiveringDecrease in
temperatureIncrease in temperatureDecrease in
temperatureIncrease in temperatureHypothalamus (the brain)

 In a feedback system, the response alters the stimulus.
Feedback can be negative (when the effect of the
stimulus is reduced) or positive (when the effect of the
stimulus is increased). E.g. the control of hormone levels
in the body, in which an increase in the level of the
hormone in the blood decreases the output by the
gland.
 A model of a feedback mechanism-

Analyse information from secondary sources to describe adaptations
and responses that have occurred in Australian organisms to assist
temperature regulation
Australian Endotherm Adaptation or response to temperature
organism or regulation
Ectotherm
Red kangaroo Endotherm Licks the inside of its paws, where skin is
thinner, and blood supply is closer to
the surface, so that heat can be easily
dumped to the outside. Evaporation
from saliva promotes the loss of heat
from the blood.
The rabbit- Endotherm The large ears of the rabbit-eared-
eared- bandicoot provide a large surface area
bandicoot to pass excess heat when it is
burrowing during the heat of day and
when it is active at dusk.

Magnetic Ectotherm Pack the walls of their mounds with
termites insulating wood pulp and align their mounds
(Amitermes north-south to maximise exposure to the sun
meridionali in the mornings and the evenings when the
s) air is cooler and to minimise exposure during
heat of day.

Bogong Ectotherm Able to avoid their bodies freezing by
moth supercooling their tissues. This process
involves reducing the temperature of the
body fluids below their usual point of
freezing and as a result, ice crystals do not
form and destroy the cells.

Identify the form(s) in which each of the following
is carried in mammalian blood:
Carbon dioxide
Oxygen
Water
Salts
Lipids
Nitrogenous waste
Other products of digestion

Substance From To Form Carried by
Oxygen Lungs Body Oxyhaemoglobi RBC’s
cells n
Carbon Body Lungs Hydrogen RBC’s and
Dioxide cells carbonate plasma
ions,
bicarbonate
ions

Water Digestive Body Water Plasma
system cells molecules
and body
cells

Salts Digestive Body As ions in the Plasma
system cells plasma
and body
cells

Lipids
Nitrogenous Liver and Kidneys Mostly as Plasma
waste body urea,
cells sometimes
ammonia
or uric
acid
Other Digestive Body As separate Plasma
products syste cells molecules,
of m and .e.g.
digestion liver glucose,
amino
acids

Explain the adaptive advantage of haemoglobin

 Haemoglobin-
 Large protein molecules found in RBC’s
 Oxygen isn’t very soluble in water, which is why it’s
carried in the haemoglobin
 It increases the oxygen carrying capacity of RBC’s by
about four times.
 Mammals require a constant and large supply of oxygen
to produce enough heat to maintain homeostasis.

 Supply can be adjusted to suit altitude
 Can bind to oxygen loosely-therefore release it quickly
 And advantage to be carried in and RBC. If just
dissolved in plasma it would upset the osmotic balance
of the blood.
 The development of RBC’s without a nucleus leaves
more room for haemoglobin.

Compare the structures of arteries capillaries and veins
in relation to their function
Artery Vein Capillary
Sketch

Description Thick, elastic, Bigger One cell thick in
muscular walls in diameter than diameter ...
arteries, has a larger
but surface area
their to volume
muscular ratio.
wall
is much thinner.

Function Carry oxygen Carry Exchange
rich blood deoxygenate materials
from lungs to d blood back between
the entire to the heart. blood and
body body cells.

Reason Blood is under They are not Large SA:V
pressure and under as allows for
needs to be much the easy
pumped pressure and exchange of
around to the only travel nutrients
body. The one way. (needed by
muscular They are cells and
walls expand pushed up waste
and contract through products)
to push the valves.
blood
through.

Describe the main changes in the chemical composition of the
blood as it moves around the body and identify tissues in
which these changes occur

 The blood circulates through two systems in the body: the
pulmonary system and the systemic system.
The pulmonary system-
 Blood flows from the heart to the lungs and then back to
the heart. Blood travels in the pulmonary artery from the
right ventricle to the lungs where carbon dioxide is
released into the alveoli of the lungs. This is then
ultimately released out of the body. Oxygen is picked up
from the alveoli and diffused into the red blood cells to
then be taken back to the heart. So via the pulmonary
system, carbon dioxide is decreased and oxygen levels
increased.

The systemic system-
 Blood flows from the heart to the rest of the body,

except the lungs, and then returns. The left ventricle
pumps oxygenated blood to the rest of the body, and as
this blood circulates in capillaries, oxygen is delivered to
the cells and carbon dioxide is picked up. Other waste
products, such as urea, are also picked up from the liver
and transported in the blood to the kidneys. Blood
flowing to the small intestines collects the products of
digestion and transports them to the liver. Glucose is
circulated in the blood stream to all cells in the body for
respiration. Deoxygenated blood returns to the heart via
the inferior and superior vena cava.

Outline the need for oxygen in living cells and
explain why removal of carbon dioxide from cells is
essential
Oxygen-
 Needed for aerobic respiration to release energy
 A constant supply of oxygen is needed for the cells,
otherwise they’ll die
Carbon dioxide
 A bi-product of respiration is carbon dioxide
 Increased carbon dioxide in blood stimulates the
breathing centre in the brain, which is why we pant after
exercise. We take in more oxygen than we give out.
 Carbon dioxide reacts with plasma (mostly water) to
form carbonic acid (which is how it’s carried around the
body). If this becomes too much, the carbonic acid
upsets the pH level-making it more acidic, poisonous.
However, we have special buffer systems to stop this.

Oxygen and Carbon Dioxide Molecules

Describe current theories about processes
responsible for the movement of materials through
plants in xylem and phloem tissue

Xylem-
 The transpiration-cohesion-tension mechanism is
currently the theory that accounts for the ascent of
xylem sap. This sap is mainly pulled by transpiration
rather than pushed by root pressure. Cohesion is the
“sticking” together of water molecules so that they form
a continuous stream of molecules extending from the
leaves down to the roots. Water molecules also adhere
to the cellulose molecules in the walls of the xylem. As
water molecules are removed by transpiration in the
leaf, the next molecule moves upwards to take its place,
pulling the stream of molecules continuously along.

Phloem-
 The pressure-flow mechanism is a model for phloem
transport now widely accepted.
The model has the following steps.
 Step 1: Sugar is loaded into the phloem tube from the
sugar source, e.g. the leaf (active transport)
 Step 2: Water enters by osmosis due to a high solute
concentration in the phloem tube. Water pressure is now
raised at this end of the tube.
 Step 3: At the sugar sink, where sugar is taken to be
used or stored, it leaves the phloem tube. Water follows
the sugar, leaving by osmosis and thus the water
pressure in the tube drops.
 The building up of pressure at the source end, and the
reduction of pressure at the sink end, causes water to
flow from source to sink. As sugar is dissolved in the
water, it flows at the same rate as the water. Sieve
tubes between phloem cells allow the movement of the
phloem sap to continue relatively unimpeded.

Perform a first-hand investigation to demonstrate
the effect of dissolved carbon dioxide on the pH of
water

Changing pH
Aim: to demonstrate the effect of dissolved carbon dioxide on the pH
of water.
Apparatus:
 Hydrochloric acid (0.1M)
 Calcium carbonate- powered
 Water
 Conical flask with side arm and connecting tubes
 Beaker
 Stopper
 Measuring cylinder
 Stop watch
 Universal indicator
 scales

 Method:
 set up apparatus as shown
 measure 30ml of hydrochloric acid and pour it into the
conical flask
 Measure 40ml of water and place it in the beaker, add a
few drops of universal indicator and record pH.
 Weigh 10g of calcium carbonate. Slowly pour into flask and
quickly cover with stopper. Once the calcium carbonate is
in contact with acid begin timing. Make sure the tube is
placed in water.
 Record pH, measure at one minute intervals for five
minutes
 Repeats steps 1-5 three times and record total average of
results
 Repeat steps 1-5. Controlled reaction.
 Repeat step 7 three times and record total average of
results.

Results:

Experiment 2 Experiment 3
Experiment 1

Time 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

pH 6.5 6.5 6 5.5 5.5 6.5 6 5.5 5 5 6 6 5.5 6 5

Conclusion:
When carbon dioxide dissolves in water, it produced carbonic acid,
which causes a decrease in pH, from pH of 6.5 to 5.5 in distilled
water.

Perform a first-hand investigation using the light microscope
and prepared slides to gather information to estimate the size
of red and white blood cells and draw scaled diagrams of each

Analyse information from secondary sources to identify
current technologies that allow measurement of oxygen
saturation and carbon dioxide concentrations in blood and
describe and explain the conditions under which these
technologies are used

Biosensers-
 Made analysing blood gases quicker and more accurate.

 A biosensor is a device with a transducer and a

bioreceptor, usually one that recognises specific
biochemical molecules. The bioreceptor reacts
specifically with the substance to be detected and the
transducer, which may be electrochemical, optical or
thermal, converts the biochemical signal into an
electrical signal

Sensors
 A sensor is a device that translates a physical or
chemical property into an electrical signal that can be
measured. The key component is the transducer or
signal-converting element that converts the poverty to
be measured into a signal. Sensors usually use either
optical or electrochemical technologies. Optical fibres are
now replacing electrical wire for carrying signals in many
sensors.

 Pulse oximeter (in hospitals) - a peg is attached to the
finger of the patient where a light is transmitted through
to the other side of the finger. A photo detector on the
other side measures how much light has been
transmitted through. The amount is directly proportional
to the amount of oxygen in arterial blood.

Arterial Blood Gas Analysis
 Blood gas analysis, also called arterial blood gas (ABG)
analysis, is a test which measures the amounts of
oxygen and carbon dioxide in the blood, as well as the
acidity (pH) of the blood.
 An ABG analysis evaluates how effectively the lungs are
delivering oxygen to the blood and how efficiently they
are eliminating carbon dioxide from it. The test also
indicates how well the lungs and kidneys are interacting
to maintain normal blood pH (acid-base balance).
 Done to assess respiratory disease and other conditions
that may affect the lungs, and to manage patients
receiving oxygen therapy (respiratory therapy).
 The acid-base component of the test provides
information on kidney function.
 Blood gas analysis is performed on blood from an artery.
It measures the partial pressures of oxygen and carbon
dioxide in the blood, as well as oxygen content, oxygen
saturation, bicarbonate content, and blood pH.

Arterial Blood Analysis Device

 Testing the partial pressure of oxygen is actually
measuring how much oxygen the lungs are delivering to
the blood. Carbon dioxide is released into the blood as a
by-product of cell metabolism. The partial carbon dioxide
pressure indicates how well the lungs are eliminating
this carbon dioxide.
 A related value is the oxygen saturation, which
compares the amount of oxygen actually combined with
hemoglobin to the total amount of oxygen that the
hemoglobin is capable of combining with.

Procedure-
 Oxygen Concentration In Blood
 Sample of blood taken
 Diffuses through a gas permeable membrane
 This produces an electrochemical reaction
 Which produces a current
 This current of proportional to oxygen concentration
 Carbon Dioxide Concentration In Blood
 Sample of blood is taken
 Diffused through a gas permeable membrane
 This changes the pH level in the solution
 The change in pH is proportional to carbon dioxide
concentration.

Analyse information from secondary sources to identify the
products extracted from donated blood and discuss the uses of
these products
Donated blood- Broken down into:
 RBC’s- used to carry oxygen. Given to people with anaemia
whose people don’t make enough RBC’s or people who’ve
lost a lot of blood
 WBC’s- used to combat infection. Given to people with
cancer of the blood e.g.- leukaemia. Used vary rarely-
usually antibiotics are used
 Platelets-used for blood clotting. Given to people with
cancer of the blood because they don’t make enough
platelets
 Plasma-also used for blood clotting. Used to treat people
with haemophilia. Used to adjust osmotic pressure of blood
and to pull fluids out of tissues.
 Immunoglobins-infection fighting parts in plasma. Used to
treat people with difficulty fighting infection.
 Whole blood-only given when >20% of blood is lost

Donated Blood Platelets and Plasma

Analyse and present information from secondary
sources to report on progress in the production of
artificial blood and use available evidence to
propose reasons why such research is needed

Artificial Blood-
 Need to be stored at room temp. and have a prolonged
shelf life; 3-4 weeks
 World wide shortage of donor blood due to HIV/AIDS,
Mad Cow Disease, new screening etc
 Need a safe and effective way to get a new blood source
(considering there’s no donor blood anymore)

Used to:
 Increase plasma volume- artificial plasma expanders are
used for severe burns- so the blood can clot and heal
 Carry oxygen and carbon dioxide- not other substitutes for

any other nutrient yet
Types
 Perflurochemicals (PFC’s)

 Can dissolve about 50 times more oxygen than blood
plasma
 Cheap and free of biological materials- no risk of infection

 To work must combine with other materials to mix with the
blood stream-usually lipids.
 Haemoglobin- based oxygen carriers (HBOCs)

 Oxygen bonds chemically but only dissolves in PFC’s

 Not contained in a membrane-don’t require blood matching

PROBLEMS
 Doesn’t stop haemoglobin from oxidising (doesn’t have
the enzymes to stop it)- once oxidised it can’t carry
oxygen
 Membrane protects the haemoglobin from degradation
and toxic effects of haemoglobin
 Alters blood flow through smallest vessels
 Only stay in circulation for 20-30 hours, instead of
RBC’s-100days
 If in an accident you’ll usually be given saline (sodium
chloride- same concentration as blood and other tissues-
0.9%) OR dextrose- 4% glucose and 0.18% saline
solution.

Choose equipment or resources to perform a first-
hand investigation to gather first-hand data to draw
transverse and longitudinal sections of phloem and
xylem tissue

 Xylem carries water and minerals upward from the root
hairs (where the water comes from). Due to capillarity
and the transpiration stream. They are dead tissues and
narrow.
 Phloem carries minerals produced by photosynthesis;
mainly sugar, up and down the plant.
 Symplastic Loading- materials travel in the cytoplasm
from the mesophyll cells to the sieve element (the
phloem) through plasmodesmata. This means a lot of
plasmodesmata are required.

 Apoplastic Loading- nutrients travel through the cell
walls until they get to the sieve element. They then
cross the cell membrane into the phloem. The sieve
element becomes loaded with sugars (nutrients) and
dumps them into a sink cell. This keeps pressure of the
phloem constant.

Explain why the concentration of water in cells
should be maintained within a narrow range for
optimal function.
 Water concentration in cells is critical for most living
organisms. It must remain constant as slight changes may
lead to cell death. This is because:
 Water is essential for life. Water is the solvent for all the
metabolic reactions in living cells. It takes part directly in
many of them such as photosynthesis and is formed as a
product in many others including respiration.
 Living cells function best in an isotonic environment (one in
which the solute concentration is the same both inside and
outside the cell). They are very sensitive to changes in
solute concentration and as consequence may lose or take
in large amounts of water by osmosis.
 Changes in concentration of water in the cell will affect the
concentration of dissolve substances, which in turn can
affect the metabolic function

Explain why the removal of wastes is essential for
continued metabolic activity.

 Wastes products are constantly being formed as a result
of metabolic processes that occur in cells. However, the
removals of these wastes are essential because:
 Some of the wastes build up as toxins and could poison
the cells. For example:
 Carbon dioxide

 Nitrogenous wastes

 If allowed to accumulate in cells and tissues, these
wastes could disrupt or slow down metabolic reaction
rates

Different animals excrete different wastes products
 Aquatic animals, fish and invertebrates mostly excrete

ammonia. Ammonia is toxic, but can be released
continuously and directly into the water and is quickly
dispersed
 Terrestrial animals excrete nitrogenous waste as either

urea or uric acid. This is because terrestrial animals need
to conserve water by converting ammonia into less toxic
forms and excrete it periodically. Urea is soluble and is
released in urine while uric acid is almost insoluble and
non-toxic.

Identify the role of the kidney in the excretory
system of fish and mammals.

 Kidney is an organ of filtration, reabsorption and
secretion. The primary role of the kidneys is
osmoregulation, the regulation of the water and salt
concentrations in the body.
 The kidney forms urine by removing wastes such as
nitrogenous wastes, salts, other unwanted metabolic
products and excess water, from the blood. The kidney
maintains the balance of salts and water in the body,
and so has a vital role in homeostasis.
 NB: The structural and functional unit of the kidney is
the nephron. There are approximately 1 million
nephrons in each human kidney. Each nephron is made
up of glomerulus and tubules.

Explain why the processes of diffusion and osmosis
are inadequate in removing dissolved nitrogenous
wastes in some organisms.

 The processes of diffusion and osmosis are
inadequate for removal of wastes because:
 Diffusion is too slow and non-selective of solutes
 Diffusion would mean all salts would be
eliminated along with glucose and vitamins;
whereas the body needs to retain some salts
and nutrients
 Osmosis would mean that wastes would stay in
the body and that water would leave

Distinguish between active and passive transport
and relate these to processes occurring in the
mammalian kidney.

 In the kidneys both forms of transport are used in
regulating the body fluid composition.
 Passive transport requires no energy. Passive transport
occurs in filtration and in the osmosis of water back into
the blood.
 Active transport requires energy from metabolism (ATP).
Active transport occurs in the secretion of substances
into the nephron, the active transport of nutrients back
into the blood, and the selective reabsorption of salts
required by the body. These processes require energy,
as they would have to go against the concentration
gradient.

Explain how the processes of filtration and
reabsorption in the mammalian nephron regulate
fluid composition.
 Filtration and reabsorption occurs in the nephron.
 Filtration involves the removal of substances from blood
if they are small enough to be forced through the
glomerulus and into the Bowman’s capsule. The
glomerulus acts like an ultra filter and particles that are
too large such as proteins cannot pass through the
Bowman’s capsule.
 Filtered blood then moves along the tubules. Useful
substances such as water, glucose, amino acids,
vitamins, hormones and inorganic salts are reabsorbed
through diffusion and osmosis.
 Hence, the processes of filtration and reabsorption
regulate body fluid composition as it perform the
complex balancing of retaining essential substances and
removing toxic wastes from blood to maintain
homeostasis.

Outline the role of the hormones, aldosterone and
ADH (anti-diuretic hormone) in the regulation of
water and salts levels in blood.

 Adolsterone is a steroid hormone produced by the
adrenal cortex of the kidney. Its role is to maintain a
balance of water and salts in the body. It stimulates the
nephron to increase the concentration of sodium ions
leading to a decrease in reabsorption of potassium ions
and more water diffusing into blood at the nephron. This
causes a rise in blood pressure and volume.
 Anti-diuretic Hormone (ADH) is a hormone produced by
the hypothalamus and stored in the pituitary gland that
stimulates the nephrons to absorb more water. This acts
to decrease urine volume.

Define enantiostasis as the maintenance of
metabolic and physiological functions in response to
variations in the environment and discuss its
importance to estuarine organisms in maintaining
appropriate salt concentrations.

 Enantiostasis is the maintenance of metabolic and
physiological functions in response to variations in the
environment.
 To estuarine organisms the maintenance of salt
concentrations is important. Many of the organisms
cannot control salt and water levels, instead they exhibit
enantiostasis in order to survive the daily change in
salinity.
 Ways in which some estuarine organisms function to
overcome daily change in salinity:

 Fast-swimming organisms can move away from area
with high salinity
 Molluscs can close their shells
 Bottom dwellers burrow or dig deep into mud or sand
 Halophytes tolerates changes in salinity by having a
special mechanism to control their level of slat
 Saltbushes have special salt excretion glands on their
leaves
 Some mangroves excrete salt from special glands in
their leaves

Describe adaptations of a range of terrestrial
Australian plants that assist in minimizing water
loss

 Some adaptations to limit water loss that Australian
plants exhibit include:
 Hard or thick waxy cuticles on leaves, such as eucalypts
 Hairy leaves, stems and even flowers to restrict air flow
and evaporation, such as alpine groundsel
 Leaves that droop or roll to reduce the exposure of
stomates, such as spinifex
 A tough, woody structure that prevents plants wilting
even when they lose water, such as alpine groundsel
 Small leaves, such as saltbushes
 Leaves with a reduced number of stomates
 Widely spreading or deep root systems to obtain more
water, such as mulga

Perform a first-hand investigation of the structure of
a mammalian kidney dissection, use a model or
visual resource and identify regions involved in the
excretion of waste products.

Gather, process and analyse information from
secondary sources to compare the process of renal
dialysis with the function of the kidney.

Kidney function Renal dialysis
A natural body process An artificial process replacing
damage kidney
Performed by two fist-sized organs Performed by a large machine
attached to a variety of
computer and other equipment
Removes wastes continuously Performed repeatedly under
hospital conditions (two or three
times each week, for several
hours each time)
Varies output automatically, Concentrations of substances in
depending on concentrations of blood and dialysis fluid are
wastes in blood monitored by computers so that
most wastes are removed
during treatment
Wastes may be removed by both Wastes removed by diffusion
diffusion and active transport

Present information to outline the general use of
hormone replacement therapy in people who cannot
secrete adolsterone.

 Aldosterone is used to regulate water and salt
reabsorption. When aldosterone cannot be secreted, the
excretory system will not be as efficient. The person
cannot maintain homeostasis and become severely
dehydrated. The hormone replacement is taken on a
regular basis, to maintain balance of salts. The main
artificial substitute for adolsterone is called
fludrocortisone. Appropriate hormone replacement
therapy can enable patients to manage symptoms such
as fluid retention and high blood pressure and lead
normal lives.

Analyse information from secondary source to
compare and explain the differences in urine
concentration of terrestrial mammals, marine fish
and freshwater fish.

Type of Urine components and Explanation
animal concentration
Terrestrial Concentrated urine, Excess salts and other wastes are
mammal usually composed of excreted dissolved in water. Water
(e.g. bilby) urea, salts, other needs to be conserves, urine
wastes and water. produced is concentrated.
Nitrogenous wastes present as urea
- it is less toxic than ammonia and
can be present in higher
concentration
Freshwater Large quantities of very Freshwater fish absorb large volumes of
fish dilute urine, usually water through gills and mouth thus
(e.g. native composed of much water must be excreted.
bass) ammonia, small Ammonia is suitable - sufficient
amounts of salts and water to dilute it. Salts - low
large amount of water concentration in fresh water,
therefore fish take up salts from
water as replacement.

Marine fish Small quantities of Marine fish constantly lose water - high
(e.g. concentrated urine, salt environment. Excrete little water in
whiting) usually composed of concentrated urine containing high
trimethylamine oxide, levels of non-toxic trimethylamine oxide
other wastes and small and salts.
volumes of water

Use available evidence to explain the relationship
between the conservation of water and the
production and excretion of concentrated
nitrogenous wastes in a range of Australian insects
and terrestrial mammals.

 Type of nitrogenous wastes (uric acid or urea) and its
high concentration enable these organisms to reduce the
amount of water they lose to remove wastes. This helps
them to conserve water in harsh and dry environments.

Process and analyse information from secondary
sources and use available evidence to discuss
processes used by different plants for salt
regulation in saline environments.
 Mangrove:
 Shrubby tree that grows in estuaries
 Its roots have a layer of cells that actively restrict the movement of
salt into xylem vessels
 Able to excrete salt through the underside of its leaves. Salt crystals
accumulate on leaves and so salt is lost when older leaves fall from
plant
 Saltbush:
 Tolerate salinity levels that kill most other plants
 Excrete large amount of salt through their leaves
 In general plants removed salt for regulation by:
 Salt can be redirected towards drying leaves, so when drop off the
plants, the salt is removed
 Salt excretion glands actively excrete salt by allowing it to crystallize
and be blown or washed away
 Osmotic adjustment

Perform a first-hand investigation to gather
information about structures in plants that assist in
the conservation of water.

Maintaining a balance

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