MAINTAINING A BALANCE1. MOST ORGANISMS ARE ACTIVE IN A LIMITED TEMPERATURE RANGE

IDENTIFY THE ROLE OF ENZYMES IN METABOLISM, DESCRIBE THEIR CHEMICAL COMPOSITION AND USE A SIMPLE MODEL TO DESCRIBE THEIR SPECIFICITY ON SUBSTRATES

◊ Metabolism: the sum of all chemical processes or reactions occurring within an organism.

◊ The rate of reaction is maintained and controlled by large proteins called enzymes

◊ Role in metabolism:

o Enzymes are biological catalysts that support the function of enzymes

o It is a substance that increases the rate of reaction without being changed itself

o Enzyme present -> less energy required to catalyse a chemical reaction

o Enzyme absent -> more energy required and vice versa

◊ Chemical Composition:

o Most enzymes are proteins (a protein is long chain of amino acids joined together by polypeptide bonds)

o A reactant in an enzyme-catalysed reaction is called a substrate

o The area of the enzyme that binds the substrate is called the active site – where the action takes place

◊ Specificity:

o Enzymes are highly specific -> one enzyme catalyses one particular substrate and only that substrate

o This is due to the shape of the active site of the enzyme matches the shape of the substrate material

o When products are formed, they leave the enzyme surface.

◊ Models to explain Specificity:

o Lock and key: suggests that the substrate sits exactly into the active site of the enzyme like a key fit into a lock.

It assumes that the enzyme has an unchanging shape

o Induced fit: suggests that the binding of the substrate induces a temporary change in the shape of the enzyme.

The new shape better accommodates he shape of the substrate.

IDENTIFY THE PH AS A WAY OF DESCRIBING THE ACIDITY OF A SUBSTANCE

◊ pH is the measure of the acidity or the alkalinity of a substance. It is a measure of the concentration of hydrogen ions

◊ pH scale ranges from 1 – 14:

o below 7 -> acidic

o above 7 -> alkaline

o 7 -> neutral

EXPLAIN THE MAINTENANCE OF A CONSTANT INTERNAL ENVIRONMENT IS IMPORTANT FOR OPTIMAL METABOLIC EFFICIENCY

◊ Enzymes facilitate the chemical reactions that are vital to life

◊ However, enzymes are more efficient within a limited range of environmental conditions: perfect temperatures, pH

and substrate concentrations.

◊ If any of these factors are compromised, enzymes will denature, enzyme activity will decrease and so will metabolic

efficiency as a result

◊ Hence, a constant internal environment is needed so that enzymes will always be working at an optimum rate, and thus

metabolism will be at an optimum efficiency.

DESCRIBE HOMEOSTASIS AS A PROCESS BY WHICH ORGANISMS MAINTAIN A RELATIVELY STABLE INTERNAL ENVIRONMENT

◊ Homeostasis: the process by which an organism maintains a relatively stable internal environment, despite changing

external environmental conditions

◊ This is important for enzymes, in which by keeping the body stable at its optimum conditions, we allow the optimal

conditions of enzymes to be met. This in turn allows the body to carry out its reactions efficiently

◊ Homeostasis allows the enzyme’s optimal conditions to be met and the body to work as efficiently as possible

◊ Conditions controlled by homeostasis include: body temperature, pH, water and salt concentrations, sugar levels and

levels of dissolved gases.

EXPLAIN THAT HOMEOSTASIS CONSISTS OF TWO STAGES:

◊ Detecting changes from the stable state: (stage 1)

o These changes are detected by receptors. Receptors can range from a patch of sensitive cells to complex

organs like eyes and ears.

o These changes are caused by the internal and external environment

o Any change or information that catalyses a response is called a stimulus

o Sends messages to the Central nervous system (brain + spinal cord)

o Receptors detect stimuli -> organisms then react to change

o Example : If our body temperature rises, the temperature rise in the blood stimulates the brain’s frontal

hypothalamus (and inhibits the posterior hypothalamus). Alternatively, when a mammal is exposed to cold,

skin receptors increase their activity, sending more nerve impulses to the posterior hypothalamus. Plants

detect gravity, light intensity and direction, and the length of the period of darkness.

◊ Counteracting changes from the stable state: (stage 2)

o After receptors detect changes, organisms can then react to the change.

o This type of response will counteract the change to ensure the stable state is maintained

o Effectors bring about change by movement. Effectors can either be muscles or glands

o Example : After detecting the rise in temperature, the hypothalamus then stimulates heat loss by increasing

blood circulation through the skin, increasing sweating and decreasing metabolic activity and muscular activity.

Thus, the body’s temperature is lowered. After detecting the drop-in temperature, activity in the posterior

hypothalamus stimulates the sympathetic nervous system to activate mechanisms that conserve heat. Plants

may, after detecting increase in concentrations of fluids, release abscisic acid from chloroplasts so there is a

closing of stomates and an increase in the production of watertight resins.

OUTLINE THE ROLE OF THE NERVOUS SYSTEM IN DETECTING AND RESPONDING TO ENVIRONMENTAL CHANGES

◊ The Nervous system provides rapid coordination of internal organ systems and detects and responds to environmental

changes. The Nervous system consists of:

o Central Nervous System (CNS) – consists of the brain and spinal cord; receives information, interprets

information and initiates a response

o Peripheral Nervous System (PNS) – nerves branching throughout body; A means of communication throughout

the body; passes messages rapidly to the CNS and back to the body – allowing the body to respond to changes

it perceives.

◊ Response to changes:

o Counteract changes via the stimulus-response pathway (i.e. stimulus, receptor, control centre, effector,

response)

o For example, the stimulus of high blood pressure reaches he receptor the hypothalamus, which also acts as the

control centre. Effectors like blood vessels stimulate responses such as vasodilation, allowing for a decrease in

blood temperature. The response is generally an example of a negative feedback system; producing a response

that is opposite to the initial situation, then cancelling itself out once the optimal conditions are re-achieved

Table 1: Responding to body temperature increases in mammals

effector Response

Hairs on the body - raise Goosebumps are an attempt to trap a layer of warm air around the body to reduce the amount of heat lost by radiation, convection and conduction.

Arterioles in the skin narrow

Vasoconstriction - muscular walls of the small blood vessels known as arterioles constrict so that most blood flow is redirected to the core of the body, preventing heat loss from the cooler body surface (heat is carried throughout the body in the bloodstream)

Muscles Shivering brought about by rapid small muscle contractions generate heat in the body

Thyroid gland Heat gain centre stimulates the activity of the thyroid gland, causing it to speed up/increases metabolism

Table 2: Responding to body temperature decreases in mammals

effector Response

Arterioles in the skin expand/dilate

Vasodilation - blood carrying heat is directed towards the surface of the body so that heat can be lost by conduction, convection and radiation to the surroundings

Sweat glands Liquid sweat is secreted through the sweat pores onto the surface of the skin and heat is removed from the body to evaporate

the liquid

Thyroid gland Decreased metabolism - heat loss centre causes thyroid gland to lower the rate of metabolism, generating less heat

IDENTIFY THE BROAD RANGE OF TEMPERATURES OVER WHICH LIFE IS FOUND COMPARED WITH THE NARROW LIMITS FOR INDIVIDUAL SPECIES

◊ Ambient Temperature: Temperature of the environment

◊ Room Temperature: Temperature inside a temperature-controlled environment

◊ Most life is found in a temperature ranging of around 0 – 45’C

o Life can still be found in areas with temperature as low as -70’C and of more than 200’C in the deep ocean

o Despite this broad range, most individual animals only tolerate a narrow temperature range

As land temperature varies more than aquatic temperature, land animals naturally need to be better

adapted to accommodate changes in ambient temperature

◊ Examples:

o Water-holding frog: 3’C –> 39’C

o Platypus: -8’C –> 34’C

o Sydney Blue Gum: -1’C –> 34’C

COMPARE RESPONSES OF NAMED AUSTRALIAN ECTOTHERMIC AND ENDOTHERMIC ORGANISMS TO CHANGES IN THE AMBIENT TEMPERATURE AND EXPLAIN HOW THESE REPONSES ASSIST TEMPERATURE REGULATION

DESCRIBE ADAPTATIONS AND RESPONSES THAT HAVE OCCURRED IN AUSTRALIAN ORGANISMS TO ASSIST TEMPERATURE REGULATION

◊ Endotherms: organisms that use internal processes such as metabolism to maintain a constant internal temperature

E.g. mammals and birds

◊ Ectotherms: dependant on energy of the ambient environment to regulate body temperature e.g. invertebrates, fish,

reptiles, amphibians.

◊ Behavioural adaptations: the ways an organism behaves that help it survive in its natural environment

◊ Structural adaptations: have a connection with the physical features of an organism

◊ Physiological adaptations: a feature that helps to regulate a function within an organism

Table 3: Red Kangaroo (Endotherm)

Ambient Env. Physiological Structural Behavioural

Cold conditions (winter months)

Increased metabolic rate to create more heat within the body Vasoconstriction

Layer of fur creates and layer of insulation between the skin and the hair and allows the kangaroo to stay warm

Basking in the sun

Warmconditions

(Summer months)

Decrease in metabolic rate which reduces the amount of heat within the body

- Panting to release heat - Exposed areas of skin on the forelegs to increase evaporative cooling of the blood from this area- vasodilation. - Shunting blood from the tail to the exposed areas of the skin on the forelegs to increase heat loss.

- Nocturnal - Licking forelegs to increase evaporation from the skin - Sitting in the shade

◊ Red kangaroo is the largest marsupial in Australia. Lives in grasslands of dry and arid central part of the country. In this

habitat, temperatures vary from 5’C to 38’C.

◊ For these reasons, the Red kangaroo needs many adaptations to accommodate these drastic changes in temperature

and retain its optimum temperature range at 37.5’C

Table 4: Diamond Python (Ectotherm)

Climate Physiological Structural Behavioural

Cold conditions (winter months)

Lies on eggs and shivers to increase the temperature of incubation

Dark in colour to absorb heat and can therefore tolerate colder temperatures than most snakes

» Basks in the sun to raise body temperature » Hibernation » Migration to warmer areas

Warm conditions (summer months)

» Is nocturnal, so hunts at night to escape the heat during the day » Burrowing during the day

◊ The Diamond Python lives in a variety of habitats (rainforests, temperate forests, grassland, caves and hollow trees).

◊ Eats small mammals, bats, birds and lizards.

◊ Its optimum temperature around 20’C however this depends on the ambient temperature of the python’s surroundings

Comparing the Responses of Endotherms and Ectotherms:

◊ Endotherms need to have a high metabolic rate to maintain this optimum temperature rate in cold conditions and thus,

need to eat large amounts.

◊ Ectotherms do not need to do this however they have greater restrictions placed on their activity as a result.

◊ In hot conditions endotherms, must have specific adaptations to these environmental changes to regulate heat gain so

not to raise their temperature above their optimum temperature level as this can cause severe damage.

◊ This is the same for both endotherms and ectotherms in relation to cold climates.

◊ Ectotherms are not found in extremely cold climates.

IDENTIFY SOME RESPONSES OF PLANTS TO TEMPERATURE RANGE

◊ Plants are ectotherms and cannot maintain a constant temperature. They have various adaptations that enable them to

survive a range of temperatures:

Adaptation Effect

Leaf Fall By dropping leaves, there is less SA exposed to hot conditions and reduces the amount of water lost through transpiration

Radiation Some plants have shiny leaves to reflect solar radiation

Heat Shock Proteins Proteins produced to stop the denaturing of cells

Transpiration Evaporation of water through stomates of the leaves cools the plant. Water travelling up the stem also cools plant

Die-back Shoots and leaves of the plants may die, the bulbs, roots and rhizoids (root hairs) will be left in soil to grow back when conditions improve

Orientation of leaves Leaves may have vertical orientation (hanging down) so that sunlight exposure is reduced

Seed Dispersal Some plants require extreme heat to open their coats. Only when they germinate

Vernalisation Some plants must be exposed to cold conditions for the plant to produce flowers and reproduce

DEVELOP A MODEL OF A FEEDBACK MECHANISM

2. PLANTS AND ANIMALS TRANSPORT DISSOLVED NUTRIENTS AND GASES IN A FLUID MEDIUM

IDENTIFY THE FORM(S) IN WHICH EACH OF THE FOLLOWING IS CARRIED IN MAMMALIAN BLOOD:

Table 5: Forms in which Material is carried in Mammalian blood

Materials Form carried in mammalian blood

Carbon Dioxide Leaves cells and dissolves in plasma to form bicarbonate ions (HCO3-). Oxygen This dissolves into the plasma, and combined with haemoglobin to form oxyhaemoglobin

Water Produced by body cells from respiration, and travels through the body as water molecules in the plasma

Salts Carried in the plasma in the form of ions. E.g. Sodium ions (Na+), calcium ion (Ca2+) etc.

Lipids Carried as lipid droplets but digested lipids are carried in the form of fatty acids and glycerol in plasma

Nitrogenous waste Carried in the plasma in the form urea (NH2CONH2). Formed through the breakdown of proteins

Other products of digestion Sugars are carried in the form of glucose. Proteins are carried in the plasma in the form of amino-acids.

EXPLAIN THE ADAPTIVE ADVANTAGE OF HAEMOGLOBIN

Table 6: Advantages of Haemoglobin

Adaptive advantage Explanation

Each haemoglobin molecule contains four haem units

◊ Increases the oxygen-carrying capacity of blood◊ One haemoglobin molecule can bond with four oxygen molecules◊ More oxygen can be carried in blood cells by haemoglobin than could be

carried dissolved in plasma◊ Can carry far more oxygen than if dissolved in plasma

Oxygen affinity (ability to bind oxygen) is increased once the first O2 molecules binds with haemoglobin

◊ Ability to bind oxygen increases once the first oxygen molecule binds to it ◊ Increases rate and efficiency of oxygen uptake◊ Result: very small increase in oxygen concentration in the lungs can result in

a large increase in the oxygen saturation of blood

Capacity to disassociate increases at lower pH levels -> Bohr effect

◊ Capacity to release oxygen increases when CO2 is present ◊ Metabolising cells release carbon dioxide, which combines with water to

form carbonic acid and this lowers pH◊ Haemoglobin has a reduced affinity for oxygen at lower pH so it releases

oxygen in tissues where it is needed

Capable of binding with carbon dioxide but has higher attraction for oxygen

◊ Haemoglobin has an increased ability to pick up carbon dioxide once it has released oxygen

COMPARE THE STRUCTURE OF ARTERIES, CAPILLARIES AND VEINS IN RELATION TO THEIR FUNCTION

◊ Arteries: o Carry blood away from the hearto Thick muscular wallo Carry oxygenated blood (except for pulmonary artery)o Blood in arteries are under high pressure

◊ Veins :o Thin-walledo Valves are present to prevent backflow of blood o Carries blood back to the hearto Carry deoxygenated blood (except for pulmonary vein)o Blood is under low pressure; movement is assisted by body muscles

◊ Capillaries: o Thin-walled, 1cm thicko Carry blood between veins and arteries

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

◊ Pulmonary circuit:

o Blood flows from the heart to the lungs and back to the heart

o Blood under low pressure

o Rate of blood is faster

o Very little body fluid is formed

o Blood returning to the body contains high CO2

levels and high O2 levels

◊ Systematic circuit:

o Blood flows from heart to body

o Blood under high pressure due to contraction of

left ventricle of heart, but gradually lessens

o Blood pressure forces some fluid out of the blood

to become body fluid

Tissue Main Changes in Blood

Lung » Increase in oxygen » Decrease in carbon dioxide

Villi of small intestine

» Increase in glucose and other products of digestion (amino acids, lipids, vitamins, minerals, water)

Kidneys » Decrease in nitrogenous wastes (salts and water to form urea)

Other body tissues

» Decrease in oxygen » Decrease in glucose » Increase in carbon dioxide

o In tissues, blood gives up oxygen and other ions and minerals;

produces waste products e.g. Urea, CO2

OUTLINE THE NEED FOR OXYGEN IN LIVING CELLS AND EXPLAIN WHY REMOVAL OF CARBON DIOXIDE FROM CELLS IS ESSENTIAL

◊ Cells require oxygen for respiration – a process vital for making energy

(which we call ‘ATP’)

o Glucose + oxygen + water + ATP

o CO2 is a by-product of this reaction and must be removed to

maintain optimum pH balance in the blood

→ Removing excess CO2 prevents a build-up of pH-lowering carbonic acid that forms when CO2

dissolves in water, and affects enzyme activity

DESCRIBE CURRENT THEORIES ABOUT PROCESSES RESPONSIBLE FOR THE MOVEMENT OF MATERIALS THROUGH PLANTS IN XYLEM AND PHLOEM

◊ Phloem :

o Movement of materials through the phloem is called Translocation. This is an active process that requires energy.

Transports materials up and down

o It is referred to as the source-sink pathway driven by a pressure gradient generated osmotically.

o Loading at the source can either be:

Symplastic loading : where sugars and nutrients move in the cytoplasm from the mesophyll cells to

the sieve elements through the plasmodesmata or,

Apoplastic loading : where movement occurs along a pathway through the cell walls until they reach

the sieve element, then across the cell membrane to enter the phloem tube

o Once loaded at the source, the materials flow towards a sink.

o Sinks are regions of the plant where the nutrients are actively

removed from the phloem, such as roots, stems and flowers.

The pressure difference between the source and the sink

regions drives the phloem sap.

◊ Xylem :

o The Transpiration stream theory persists that due to the

physical forces of water and ions being removed from the plant

stomates by passive transport (i.e. Transpiration), causes a

column of water to be sucked up the stem by the evaporative

pull, also the low concentration of water at the roots allows

more water to diffuse

o Once water has been absorbed into the root plants (by

osmosis), along with mineral ions (by diffusion and active transport), these substances move across the root into

the xylem. A small amount of root pressure results from the continual influx of more water and ions, hence

forcing the solution already present upwards (due to pressure build-up), however this is usually not enough.

o The constant loss of water, leads to a transpiration stream (which is the constant upward flow of water through a

plant), this is because of water’s 2 properties, which are adhesive forces (ability of molecules to attach to walls),

and cohesive forces (the attraction of molecules to each other), hence leading to the capillary (water rising

through bore of tissue) and hence the stream

DEMONSTRATE THE EFFECT OF DISSOLVED CARBON DIOXIDE ON THE PH OF WATER

◊ Aim : to model the effect of carbon dioxide on the pH of water

◊ Equipment:

o 25mL of distilled water

o Universal indicator

o pH probe attached to data logger

o 1 x straw

◊ Risk Assessment:

o Gloves must be worn in case of glass breaking

o The water can be corrosive due to increasing pH, it should not be ingested after use, dispose in an organic

waste container

o Straws should not be used by more than one student, to minimise contracting diseases

◊ Method:

1. In a beaker, pour water

till 25mL grade mark,

then put 3 drops of

universal indicator, this

should now change into

greenish colour

2. Then put pH probe, and

check that pH is about 7

3. Exhale air into the straw

that is dipped into the solution for about 3 minutes

◊ Result:

o After about 30 seconds, the colour of the solution began to change into pale yellow, and the pH on the data

logger started decreasing

o This is because carbon dioxide forms a weak acid, carbonic acid (H2CO3), so the water becomes more acidic.

Carbonic acid in water disassociates to form hydrogen carbonate ions (HCO3-), and some carbonate ions

(CO3^2+)

PERFORM A FIRST-HAND INVESTIGATION USING THE LIGHT MICROSCOPE AND PREPARED SLIDES TO GATHER INFORMATION TO ESTIMATE THE SIZE OF RED AND BLOOD CELLS AND DRAW SCALED DIAGRAMS OF EACH

◊ Aim : To estimate the size of red blood cells and white blood cells seen with the light microscope

◊ Equipment :

o Light Microscope

o Prepared slides of human blood

o 1mm sized mini-grid plastic paper

o Pencil and drawing paper

◊ Risk Assessment :

o Slides can be sharp or unseen flint pieces of glass, gloves and glasses should be worn

o Use commercially prepared microscope slides of blood and not fresh blood, to eliminate the risk of contracting

blood-borne disease.

◊ Method :

1. The microscope on normal view, i.e. 1X, has a limited field of view of 16mm

2. Hence, set your microscope with the millimetre-square graph paper first. Then click the 1X objective lense, this

will show you what the normal eye of 16mm can see.

3. Then click the 10X objective, this will magnify the 10mm by a factor of 10. Hence you’ll see a maximum field

view of 1.6mm, and its sub-ten components (note, 1mm = 1000μm)

4. Now using the 40X objective, this now makes the initial 16mm diameter 4 times less than the 10X, so the

diameter is approximately 0.4mm. Hence the diameter is 0.4mm, or 400μm

5. Now, putting a slide of a prepared blood, 50 red blood cells exist, hence the size of 1 RBC is 400μm divided by

50 is 8μm.

6. Now for white blood cells since there are so few, it is not possible to count the number of white cells across

the diameter, even much more difficult to estimate how many would fit across the diameter. Hence, the size is

estimated by proportion in comparison to that of RBC.

◊ Result :

o Erythrocytes (Red Blood Cells)

Size: 6 - 9μm

Shape: Bi-concave (concave on both sides

Function: to transport oxygen

Have no nuclei, 5 – 6 million in every millilitre of blood

Produced in bone marrow

o Leucocytes (White Blood Cells)

→ Size: 12 - 15μm

→ Shape: irregular, can change shape

→ Function: to defend against disease

→ Have nuclei, produced in lymph glands

IDENTIFY CURRENT TECHNOLOGIES THAT ALLOW MEASUREMENT OF OXYGEN SATURATION AND CARBON DIOXIDE CONCENTRATIONS IN BLOOD AND DESCRIBE AND EXPLAIN THE CONDITIONS UNDER WHIH THESE TECHNOLOGIES ARE USED

IDENTIFY PRODUCTS EXTRACTED FROM DONATED BLOOD AND DISCUSS THEIR USES OF THESE PRODUCTS

◊ Red Blood Cells:

o Used to increase amount of oxygen that can be carried to the body’s tissues

o Given to anaemic patients (whose bone marrow does not make enough red blood cells) or who has lost a lot

of blood

Technique Arterial blood gas analysis

Description of how the technology works

Electrochemical: uses a sensor that translates chemical properties into an electrical signal that can be measured.Involves removing blood from an artery and performing a blood test using computer-based technology to analyse the chemical components in the blood

Placement Invasive - small sample of arterial blood must be withdrawn from the patient or an arterial probe may be inserted into an artery (usually in the arm)

Information re blood gas concentration collected

Oxygen and carbon dioxide levels and pressurepH of bloodLevel of bicarbonate ions

Levels of chemicals in the blood

Conditions where it is used

Only carried out if abnormalities show up in the pulse oximeter readings or in severe cases of breathing disturbance

Study of lung disease and monitor conditions of poor gaseous exchange (respiratory disease e.g. patients with asthma, cystic fibrosis)pH and electrolyte ion levels measured gives important information about how well the kidneys are functioningGeneral: if blood oxygen content seems low or there is a risk of carbon dioxide levels being high or blood pH being too acidic

Benefits Gives more information e.g. CO2, pH, bicarbonate ions - (pressure as well as saturation readings)

Limitations Invasive - bleeding or bruising at puncture siteOnly provides information at one particular time - not continuousFeeling faintBlood accumulating under the skinInfection at the puncture site

Current and future research

Some advanced blood gas analysers can also measure levels of glucose, haemoglobin and electrolytes (salts) in the blood. Research has improved the speed of the machines and in some machines results can be obtained within a few minutes

Technique Pulse oximeter

Description of how the technology works

Two light-emitting diodes, one producing red and one producing infrared light are shone through the finger. The amount of light absorbed by arterial blood determines the level of oxygenation of haemoglobin the blood and thus oxygen saturation is calculated and displayed on a screen.

Placement Non-invasive - consists of a prove attached to the patient's finger or earlobe (anywhere where there is an extremity of blood vessels near the surface)

Information re blood gas concentration collected

Oxygen saturation Pulse rate

Conditions where it is used

General: to determine if blood oxygen is within the normal range or notSpecific: To monitor on an ongoing basis oxygen saturation and pulse rate - indication breathing and circulation are normal:

Prior to anaesthetics Whist under anaesthetics or sedation During recovery after surgery While on oxygen therapy or ventilation Who appear to have breathing difficulty or whose

circulation is abnormal Who are suffering from sleep apnoea Such as premature or newborn babies, who need

ongoing checks

Benefits Non-invasive - proceeds on a continuous basis without the need for a blood sample to be taken

Quick reading Ongoing

Limitations Cannot operate reliably with a poor signal May appear to have a good signal and be displaying a

saturation figure, but either the figure is inaccurate or gives a false sense of security

Delay Nail varnish interference Most do not measure carbon dioxide levels

Current and future research

The latest generation of oximeters (produced from 2005 onwards) have a carbon dioxide sensors and have digital signal processing. They are also designed to allow patients to move about and can be used on non-translucent body parts - particularly effective in newbornsMobile phones are being used to transmit signals

◊ Platelets:

o Essential for blood clotting

o Used for people who have cancer of the blood or lymph such as leukaemia or lymphoma. Patients undergoing

chemotherapy do not have enough blood platelets and are also given platelets extracted from donated blood

◊ Plasma:

o Liquid portion of blood, which contains blood-clotting factors (and immunoglobins).

o Used to treat people with clotting disorders such as haemophilia. Also, used to adjust the osmotic pressure of

blood and pull fluids out of tissues.

o Some products are derived from plasma.

◊ White Blood Cells:

o Another infection-fighting component of the blood.

o Only used occasionally to treat life-threatening infections when the cell count is very low or the white blood

cells are not working properly.

o Most of the time, antibiotics are used in these cases rather than giving white blood cells

◊ Plasma derivatives:

o Separate functions of clotting factors found in whole plasma:

→ Immunoglobins : are infection fighting parts of the blood plasma. Used to treat people who have

difficulty fighting infections and whose immune systems are not working properly because of diseases

such as AIDS.

→ Cryoprecipitate and concentrates of Factors VIII and IX are for patients who suffer a variety of

bleeding disorders.

REPORT ON PROGRESS IN THE PRODUCTION OF ARTIFICIAL BLOOD AND USE AVAILABLE EVIDENCE TO PROPOSE REASONS WHY SUCH RESEARCH IS NEEDED

◊ Artificial blood is only currently used for:

o Increased blood volume – used in cases of severe burns

o Carry oxygen

◊ No substitutes have been developed yet that can replace other functions: immune defence and coagulation

◊ Benefits:

o Free of infection agents and allergens, making them non-toxic and disease-free

o Do not need refrigeration and storage; kept for longer period, 2 – 3 years

o Universal acceptance by all blood groups, allowing transfusion to a person without tests

o Readily available in large supplies, solving the worldwide problem of blood donors

◊ Proposed replacements for blood (oxygen-carrying artificial blood):

o Perfluorochemicals: synthetic materials that can dissolve about 50 times more oxygen than plasma. Cheap to

produce and, because they are synthetic, there is no risk of the material being infected by disease.

o More research is needed because Perfluorochemicals must combine with other substances in order to mix in

the blood stream.

o Haemoglobin-based oxygen carriers (HBOCs): made from haemoglobin extracted from red blood cells. Not

contained in a membrane, therefore do not require blood typing and cross-matching of blood.

o More research is needed because haemoglobin must be modified before it can be used. Current blood

substitutes do not have the enzymes that prevent haemoglobin from oxidising.

PERFORM A FIRST-HAND INVESTIGATION TO GATHER FIRST-HAND DATA TO DRAW TRANSVERSE AND LONGITUDINAL SECTIONS OF PHLOEM AND XYLEM TISSUE

◊ Aim : to draw transverse and longitudinal sections of xylem and phloem tissue

◊ Materials :

o light microscope o watch glass o scalpel

o coverslip o celery stem o dropper

o beaker of water o eosin dye solution o prepared sides of plant stem

both transversal and

longitudinal sections

◊ Risk Assessment:

o When using microscope, if care is not taken, the slide and the objective lens can break into pieces and may

cause lacerations. Only lower objective lenses while looking from the side of the microscope. While looking

through the eyepiece, the lenses must only move upwards to prevent them from crashing onto the slide and

breaking the lense and slide

o Scalpel is very sharp and can cause lacerations. While passing the scalpel, it must be done carefully and must

be pointed downwards, away from the body.

◊ Method:

o A light microscope is set up

o A celery stem that had been left in eosin dye + water solution in beaker for 24 hours was obtained. Excess dye

was washed off with water

o The thinnest section possible is cut from stem using a scalpel. Both longitudinal and transverse sections are cut

out

o The cut sections are placed under the microscope, firstly covered with coverslips.

o The longitudinal and transverse sections were observed under the microscope, firstly under low power than

high power

o The Xylem and Phloem cells were identified in longitudinal

and transverse sections

o Observed the prepared slides of the plant stems that had been

stained to show different tissues.

o Large labelled diagrams were made displaying the

Longitudinal section and transverse section of both

xylem and phloem and a diagram of the transverse

section of the stem was made.

◊ Results:

◊ Conclusion :

o The structure of Xylem is different to the structure of Phloem.

o Xylem is composed of large vessels, whose walls are thickened by lignin. Xylem also contains hard fibre cells,

which adds support to the tissue. Xylem is composed to dead tissue and transports water.

o Phloem is comprised of supporting fibre cells ad two special cell types: sieve tubes and companion cells. Unlike

Xylem, Phloem tissue is alive and uses a process of translocation to transport materials.

3. PLANTS AND ANIMALS REGULATE THE CONCENTRATION OF GASES, WATER AND WASTE PRODUCTS OF METABOLISM IN CELLS AND INTERSTITIAL FLUID

EXPLAIN WHY THE CONCENTRATION OF WATER IN CELLS SHOULD BE MAINTAINED WITHIN A NARROW RANGE FOR OPTIMUM FUNCTION

◊ Osmoregulation: regulation of water concentration to maintain homeostasis

◊ Isotonic: concentration of solutes outside and inside cell is the same. No overall movement of water

◊ Hypertonic: Concentrations of solutes is greater outside the cell than inside. Water tends to move inside the cell

◊ Hypotonic: Concentration of solutes is greater inside cell than outside. Water tends to move inside cell.

◊ Living cells work best in isotonic environments . Any change in the concentration of solutes will result in a change in the

levels of water in cells. Therefore, the concentration of water must be kept constant, to ensure the proper functioning of

living cells.

◊ Concentrations of water must be within a narrow

range because:

o It is vital for metabolic efficiency – it allows

correct concentration of substances to

diffuse across and between cells

o Cells can maintain constant osmotic pressure so water loss through processes such as urination is

compensated for

o It determines the concentrations of various substances in blood

o If not isotonic, cells are vulnerable to losing or gaining too much water – it will move by osmosis

EXPLAIN WHY THE REMOVAL OF WASTES IS ESSENTIAL FOR CONTINUED METABOLIC ACTIVITY

◊ Metabolic waste (CO2, urea, excess salt) need to be removed from the body, otherwise they will disrupt enzyme

activity, or have toxic effects (urea kills cells, excess water lowers cell metabolism by disrupting their osmotic state).

◊ Excretion: removal of metabolic wastes

IDENTIFY THE ROLE OF THE KIDNEY IN THE EXCRETORY SYSTEM OF FISH AND MAMMALS

◊ In mammals and fish, the kidney has a dual role of excreting nitrogenous wastes and maintaining water and salt

concentrations (osmoregulation)

◊ Fresh Water fish:

o Live in rivers and lakes, where the water potential is very high (losing water by osmosis, when concentrations

are high) – these habitats contain few dissolved salts and hence water is freely available.

o Freshwater fish tend to urinate frequently, as water tends to accumulate in their tissues because of passive

movement by osmosis. Their kidneys excrete excess water, as well as nitrogenous wastes.

o Their kidneys are structurally suited to this as they have large glomeruli for the filtration of blood in large

volumes. Their kidneys are not involved in salt balance, as there is no salt accumulation in freshwater fish.

◊ Marine Fish:

o Marine fish urinate less. They tend to lose body water (by osmosis), across the body surface and gills, into their

salty surroundings.

o Excess salt tends to accumulate in their bodies, moving in by diffusion from the surrounding sea water

therefore, to remove excess salt. Marine fish drink the sea water, extract the salt, use the water for

metabolism, then excrete the extracted salt to keep their bodies salt levels at a minimum.

o The kidneys also tend to conserve water rather. The kidney is also responsible for removing nitrogenous

wastes.

◊ Mammals:

o Lose water and solutes because of evaporation from the lung surface during respiration.

o The kidneys of mammals excrete urine, which is composed mainly of water and nitrogenous wastes as well as

some excess salts.

o Mammals have a complex control mechanism to ensure that a balance is maintained between the amounts of

sweat and urine excreted.

o For example, in hot weather, more water is excreted as sweat (since sweat is evaporative cooling, lowering the

bodies temperature) and thus less urine is produced. In colder weather, more water is lost in urine and very

little as sweat.

o A relatively large quantity of salts is also lost during sweating and needs to be replaced to maintain a stable

osmotic pressure. Any adjustment to the water or salt concentration in body fluids is brought about by the

hormone ADH and aldosterone. Urine may be dilute or concentrated depending on the needs of the body.

EXPLAIN WHY THE PROCESSES OF DIFFUSION AND OSMOSIS ARE INADEQUATE IN REMOVING DISSOLVED NITROGENOUS WASTES IN SOME ORGANISMS

◊ Diffusion – the movement of particles from an area of high concentration of particles to an area of low

concentration of particles.

◊ Osmosis – the movement of water particles through a semipermeable membrane into a solution of higher solute

concentration that tends to equalize the concentrations of solute on the two sides of the membrane.

◊ Diffusion and Osmosis are passive forms of transport across cell membranes. They do not require the expenditure

of energy – only active transport requires energy. Diffusion and osmosis are not selective processes; they result in

the movement of any substance small enough to cross the cell membrane where there is a concentration gradient.

◊ These processes are inadequate to remove dissolved nitrogenous wastes in some organisms as they do not occur

fast enough to maintain the requires solute concentrations in cells. They also result in the loss of substances needed

by cells. Consequently, many organisms use active transport to either remove waste substances or to return

requires substances to the cells.

DISTINGUISH BETWEEN ACTIVE AND PASSIVE TRANSPORT AND RELATE THESE TO PROCESSES OCCURRING IN THE MAMMALIAN KIDNEY

◊ Passive Transport: the movement of substances without energy expenditure.

◊ Active transport: the movement of substances across a membrane without energy expenditure.

◊ The kidney is made of millions of Nephrons. Nephrons are regulatory units of the kidney that assist in the processes of

filtration, reabsorption and secretion.

◊ The Nephron is comprised of a Bowmans Capsule, which is connected to the Proximal Tubule, leading to the Loop of

Henle, which then connects to the Distal Tubule. This all connects to the Collecting Duct which leads to the bladder.

◊ In the kidney, both types of transport occur in the nephrons:

o Passive Transport : our body wants to maintain a nice and good concentration of water, so it passively

reabsorbs and secretes water when the glomerular filtrate reaches the descending part of the Loop of Henle

after passing the proximal tubule, until our bodies are at a balance.

o Active Transport : Our bodies need to maintain glucose and other materials such as amino acids, so it actively

reabsorbs them through the filtration process.

EXPLAIN HOW THE PROCESSES OF FILTRATION AND REABSORPTION IN THE MAMMALIAN NEPHRON REGULATE BODY FLUID COMPOSITION

◊ The nephron is a regulatory unit; it selectively reabsorbs materials required to maintain homeostasis. The

readjustments occur as substances are removed from either direction – reabsorption back into the blood or secretion

back into the nephron. This regulation helps to maintain the constant composition of the blood and interstitial fluid.

◊ Filtration occurs in the glomerulus where the blood pressure forces of movement of small molecules from the blood

stream into the Bowman’s capsule (Urea, glucose, amino acids, salts and water). These then form the glomerular

filtrate

◊ Reabsorption occurs in the tubules (proximal, distal and Loop of Henle). It involves both passive and active transport –

whereby solutes required by the body are moved back into the blood stream via the capillary network (ALL glucose and

amino acids, SOME ions and water molecules)

OUTLINE THE ROLE OF HORMONES, ALDOSTERONE AND ADH (ANTI-DIURETIC HORMONE) IN THE REGULATION OF WATER AND SALT LEVELS IN BLOOD

◊ ADH :

o Also, known as Vasopressin is produced by the Hypothalamus and stored in the posterior pituitary gland.

o When water levels are too low, the Osmoreceptors in the hypothalamus monitoring the salt and water levels till

detect this change and ADH is released.

o ADH changes the water permeability of collecting ducts so that more water is reabsorbed into the blood stream

from the ducts.

o This also increases the permeability of the duct walls to urea, which diffuse in from the blood stream. These two

effects cause the urine concentration to increase.

◊ Aldosterone :

o A hormone produced by the adrenal cortex in the

adrenal gland when a decrease in the

concentration of salt is detected.

o This hormone increases the permeability of the

nephron to salt, causing more reabsorption of

sodium ions, and consequently increased

reabsorption of chloride and water (which

follows by osmosis) as they follow the sodium

ions)

o Thus, there is more salt conservation within the

body causing in the rise of blood volume and

pressure.

◊ Both ADH and Aldosterone carry out its homeostatic

functions of Osmoregulatory.

◊ In sum, Aldosterone brings about conservation of

salts (and consequently water) in the body and ADH

brings about water conservation in the body.

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: the maintenance of body functions in response to variations in the environment.

o It can be difficult to understand how it is different from homeostasis.

o Homeostasis is copying by keeping the internal environment constant, whilst Enantiostasis is coping by

changing the internal environment.

◊ Estuaries: when a river meets a see or when fresh water meets salt water

o Have a salinity gradient – high salinity at ocean and low salinity at river

Have major periodic changes in salinity due to tides, droughts etc.

Organisms with narrow salinity tolerance and that are incapable of Enantiostasis can be killed by

these changes. Some organisms are adapted to be able to avoid this issue.

o Halophytes: plants adapted to living in salt conditions. They can either tolerate higher levels or have special

mechanisms to control their levels of salt.

◊ Example: Blue Crabs:

o They suffer a decrease in internal salt composition when they leave the ocean and enter a lower salinity

environment (an estuary)

o Reduced salt-ion levels inhibit oxygen binding by haemocyanin, a large biomolecule which transports oxygen in

the crabs’ circulatory fluid (like haemoglobin)

o Blue crabs do not suffer from this they make their internal fluids more alkaline by increasing production of

ammonia increases oxygen binding by haemocyanin offsets the ion effects

DESCRIBE ADAPTATIONS OF A RANGE OF TERRESTRIAL AUSTRALIAN PLANTS THAT ASSIST IN MINIMISING WATER LOSS

Table 7: Adaptations to minimise Water loss

Adaptation Plant How?

Phyllodes Acacia group Replaced leaves with a modified leaf steams called phyllodes. They are green and able to photosynthesise life a leaf but contain fewer stomata per square centimetre than normal leaves. Therefore, reduces transpiration and water loss for the plant.

Reduce size of leaves Casuarina equisetifolia

Reduces the amount of stomata present on the leaf’s surface and therefore reduces transpiration stream.

Sunken stomates Wollemi Pine Leaves have stomates that are set into or ‘sunken’ into the leaf. The stomates have no direct contact with the sunlight so water evaporation is reduced.

Hairy Leaves Paper Daisy Leaves and sometimes stems are covered in hairs to reduce water loss. The hairs trap water that has evaporated from the plant, increasing the humidity around this area. This humidity decreases the transpiration rate.

Leaf curl Flax Lilies Will curl their leaves when temperatures get too high. Most of their stomates are located on the upper side of their leaves so when the leaves roll up, the stomates are on the inside protected from heat and evaporation.

Leaf shape Native Pig Face Grows on sand dunes so exposed to sunlight practically all day. Leaves are triangular to reduce the surface area exposed to sunlight and decreasing water loss.

PERFORM A FIRST-HAND INVESTIGATION OF THE STRUCTURE OF THE MAMMALIAN KIDNEY BY DISSECTION, USE A MODEL OR VISUAL RESOURCE AND IDENTIFY REGIONS INVOLVED IN THE EXCRETION OF WASTE PRODUCTS

◊ Aim : To identify the regions of the mammalian kidney, notably the ones involved in the excretion of waste products

◊ Equipment :

o 1 x commercially packed cow kidney

o 1 x sharp scalpel o 1 x dissecting tray o 1 x Clean laying paper

o 1 x pair of latex gloves

o 1 x tissue forceps (it helps pull skin)

o Disinfectant agent

◊ Risk Assessment:

o Gloves and protective face masks are

crucial, in case of a diseased kidney, or

the possible contracting of a disease

when touching

o Gloves are also crucial when handling

sharp objects, in case of accidental

damage

o Disinfectant agent was used on the tray,

and the paper in case of airborne

particles that may be ingested and cause

allergies or disease

o Material are carefully disposed of, to inhibit the build-up of bacteria and other organisms

◊ Method:

1. Carefully remove fat around the kidney

2. Carefully layer the tray with disinfectant agent and paper.

3. Identify and separate the three tubes entering the kidney and leaving the kidney: renal artery, renal vein and

ureter

4. Place the kidney facing sideways, and carefully cut lengthwise, using scalpel and use forceps to separate cut,

leaving the three tubes intact in one side of the dissection.

5. Observe the internal appearance to identify the cortex, medulla and pelvis. Record observations.

◊ Results : The kidney is made up of three sections: the pelvis, the medulla and the cortex where located to observe

where the processes (Filtration Reabsorption Secretion) occur

o Cortex: contains the glomeruli. It is dark red due to the capillaries. It is involved in the filtration of blood.

o Medulla: Contains nephron tubules, as can be observed by the striped appearance of the medulla. It is

involved in the reabsorption and secretion of substances

o Pelvis: it is where all the collecting ducts connect to, i.e. the collecting of urine

COMPARE THE PROCESS OF RENAL DIALYSIS WITH THE FUNCTION OF THE KIDNEY

◊ Renal dialysis : an artificial process in which the waste in the blood is removed by diffusion across a partially permeable

membrane of solution known as dialysis fluid. It is a solution of salts, glucose, dissolved gases and other substances,

wastes diffuse out of the blood into the dialysis fluid. The clean blood is

then returned.

◊ Process :

o Blood is extracted from the body from an artery and passed into a

dialyser, which is a bundle of hollow fibres made of partially

permeable membrane to help units suffering

from artery failure

o The dialyser is in a solution of dialysing fluid,

which has similar concentrations as blood. The

dialyser only allows wastes to pass through,

and not the blood cells and proteins.

o The wastes diffuse into the solution and is constantly replaced. The anti-clotting agent, heparin, is also added

to prevent clotting.

o The blood is then returned to the blood via a vein.

Feature Kidney Renal Dialysis

Structure About 1 million nephrons filtering the blood An A-V fistula in patient’s veins circulates through

semi-permeable membranes that filter toxins from

the blood. Dialysers have a compartment for blood, a

compartment for dialysate, and a semi-permeable

membrane separating the two

Function Removes urea from blood – continuous process Removes urea from blood – slow process

Other functions Maintains salt and water concentrations, and

releases hormones that regulate vital functions

(i.e. blood pressure) into the blood stream

Strictly regulates concentration of desired solutes by

altering the composition of the dialysis fluid

Amount 1.5 – 2.5L urine excreted a day 3 – 4 hour sessions in hospital, a few times a week

Filtration? yes Yes

Reabsorption? yes no

OUTLINE THE GENERAL USE OF HORMONE REPLACEMENT THERAPY IN PEOPLE WHO CANNOT SECRETE ALDOSTERONE

◊ HRT: treatment given when a gland is not producing enough of a hormone.

◊ HRT is used in Addison’s disease. People who are diagnosed with this often results in aldosterone deficiency. This

results in low blood volume, low blood pressure and low sodium content of blood.

◊ This disease is treated with an artificial replacement hormone called Fludrocortisone, which decreases the amount of

salt the body excretes. This however, can lead to side effects such as fluid retention and high blood pressure.

COMPARE AND EXPLAIN THE DIFFERENCES IN URINE CONCENTRATION OF TERRESTIAL ANIMALS, MARINE FISH AND FRESH WATER FISH

General organism Freshwater fish Marine fish Mammal

Specific example/s Carp brim, snapper human

Type of environment

hyposaline (water surrounding fish has lower concentration of salts than its cells) –high water potential

hypersaline (water surrounding fish has higher concentration of salts than its cells) –low water potential

terrestrial – water scare

Osmoregulatory problem

tends to take on water and lose valuable salts to the environment - must be able to eliminate excess water and retain salts

tend to lose water through their membranes - must conserve water and to get rid of excess salts

Type of nitrogen waste produced

creatinine, creatine, ammonia, creatinine, creatine, urea (mainly), some ammonia

urea

Characteristic of excretory organ

- many, large glomeruli- small proximal convoluted tubule- many nephrons

- large proximal convoluted tubule - small glomeruli (or absent)- few nephrons

- variable according to environmental conditions

Urine characteristics (volume, concentration, etc.)

high volume, dilute (low concentration) small volume, highly concentrated depends on water consumption

Drinks? no Constantly Moderately

Role of kidneys Primarily Osmoregulation and excretion Primarily Osmoregulation and excretion Osmoregulation and excretion

Role of gills - uptake of salts and excretion of wastes- gas exchange

- excretion of salts and wastes- gas exchange

N/A

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

◊ The dryer the environment, the greater the need to conserve water animals in dry environments will produce lower

volumes of concentrated urine.

◊ As water becomes scarcer, the nitrogenous waste changes from ammonia to urea and then to uric acid

Australian insects Australian terrestrial mammals

Examples blowfly, grasshopper human, dingo Australian hopping mouse (desert)

Availability of water in the environment

low low low

Details of excretory organs Malpighian tubules –open directly into end of digestive tract

kidneys kidneys with long Loop of Henle

Nitrogenous wasteToxicity

uric acidlow

ureamore toxic than uric acid

ureamore toxic than uric acid

Energy required for production large amount more energy required than ammonia but less than uric acid

some energy (less than uric acid)

Amount of water lost through excretion

Small (least) small small

Dilute/concentrated urine and explanation why

Concentrated uric acid –low toxicity and very little water lost.

Concentration varies within limited range, depending on water intake and the loss of water through sweating

Very concentrated urea –less water lost in desert conditions

DISCUSS PROCESSES USED BY DIFFERENT PLANTS FOR SALT REGULATION IN SALINE ENVIRONMENTS

◊ Halophyte – a plant that has successfully inhabited areas of high salinity such as Estuaries.

◊ Example : Grey Mangroves (Avicennia Marina)

◊ Leaf adaptations:

o have leaves with glands that excrete salt

o can also tolerate the storage of large amounts of salt in their leaves – which are discarded when the salt load is

too high.

o can also restrict the opening of their stomata (these are small pores through which carbon dioxide and water

vapour are exchanged during photosynthesis). This allows the mangrove to conserve its fresh water, an ability

vital to its survival in a saline environment.

o are able to turn their leaves to reduce the surface area of the leaf exposed to the hot sun. This enables them to

reduce water loss through evaporation.

◊ Root adaptations:

o Roots come in many different shapes and sizes, they all perform an important function – structural support in

the soft soils.

o have pneumatophores, which are above-ground roots. These are filled with spongy tissue and peppered with

small holes that offer structural support and allow oxygen to be transferred to the roots trapped below ground

in the anaerobic (low oxygen) soils.

o adapted to stop the intake of a lot of the salt from the water before it reaches the plant.

◊ Reproductive adaptations:

o evolved to produce seeds that float. The tide acts as the method of dispersal to avoid crowding of young

plants.

o They retain their seeds until after it has germinated and a

long, cylindrical propagule has formed. When it has

matured to this stage, the parent tree drops it into the

water, where it remains dormant until it finds the soil and

can put out roots.

PERFORM A FIRST-HAND INVESTIGATION TO GATHER INFORMATION ABOUT STRUCTURES IN PLANTS THAT ASSIST IN THE CONSERVATION OF WATER

Table 8: Adaptations of various Australian plants that assist in minimising water loss

Name of Australian Plant

Description of plants adaptations How adaptation helps minimise water loss

Spinifex grass Long, thin spiky leaves Reduces surface area of exposure to sunLeaves curved around underside into a needle; stomata is enclosed in tight area

Reducing the amount of water vapour to escape; also, less stomata exposure to drying atmosphere

Underside of leaves have tiny hairs that trap the air

Prevent convection currents and provides another mechanism to prevent water loss

Upper epidermis is covered in waxy cuticles

Reducing the ability of water to diffuse out; also, provides a reflective surface to reflect the sun’s rays

Eucalyptus Nicholii Leaves with waxy cuticles and rough surface

Reduces evaporation from leaves

Leaves hang vertically Reduces surface area exposure to sun and reducing transpiration by avoiding high radiation

Stomata open in early morning and close late morning on dry days

Less heat during the early morning, therefore less water loss

Bottle brush Petal-less flowers No more water lost through petals of plant, therefore conserving water

Waxy cuticles Reducing transpiration and provides a reflective barrier shielding against sun’s rays

Some leaves have tiny hairs all over Decrease air movement close to the surface of the plant, this reduces water loss by evaporation. These hairs also trap water molecules close to the leaf further reducing evaporation

Grevillea Dimorpha Hairy branches Traps air and prevents it from convection currentsCurved leaves Reduces the loss of water vapour therefore conserving

waterSmall leaves Less surface area exposed to sun’s rays thus minimising

transpirationWaxy cuticles Reflecting sun’s heat and therefore reduces evaporation

through the leaves