Farzaneh Module 1 Biology HSC Notes

24

description

HSC Biology Notes by farzaneh Maintaining a Balance

Transcript of Farzaneh Module 1 Biology HSC Notes

  • 1.1 Identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates:

    Enzymes are biological catalysts that reduce the amount of energy needed to start a

    chemical reaction and thus control the rate of reaction in the body.

    Every reaction and process in the body (metabolism) is controlled by a specific enzyme.

    Enzymes are proteins made up of carbon, hydrogen, oxygen, nitrogen (CHON)

    Lock & Key Model:

    o Used to show how each enzyme is specific for a specific reaction

    o The enzyme has a specific shape which fits onto the substrate forming an enzyme-

    substrate complex.

    o The reaction occurs and the enzyme breaks away from the products

    Induced-Fit Model:

    o A more recent modification of the lock and key.

    o Proposes that active slightly changes its shape to accommodate the substrate

    perfectly.

    Factors that affect enzyme activity:

    o The amount of substrate present

    o Temperature

    o Ph

    o Presence of enzymes or cofactors

    o Presence of heavy metals, e.g. Lead

  • 1.2 Identify data sources, plan, choose equipment or resources and perform a first-hand investigation to test the effect of:

    Increased Temperature Materials

    Junket tablet

    Distilled water (10ml)

    Milk (60ml)

    16 test tubes

    2 graduated pipettes

    8 thermometers

    8 water baths

    Stopwatch

    Method

    1) Prepare 8 water baths a the temperatures of 10, 20, 30, 40, 50, 60, 70 and 80 degrees by

    adjusting the temperature with varied amounts of boiling and cold water and ice. It is

    necessary to maintain the temperature of each water bath throughout the experiment.

    2) Pipette 3ml of milk into each test tube.

    3) Put 2 test tubes in each water bath labelling one A and

    the other B.

    4) Dissolve the junket tablet in 10ml of distilled water.

    5) Add three drops of junket solution to each test tube

    marked A, as B will act as a control.

    6) Shake each test tube to make sure the solution is mixed

    and place back in the water bath.

    7) Time how long it takes for the milk to curdle, using a

    stopwatch.

    8) Examine and record results.

    Conclusion

    As the temperature increases so does the rate of

    reaction.

    Each enzyme has an optimal temperature

    Change in ph Materials

    5 different bottles of solution (ph or 1,

    3, 7, 9, 11)

    5 test tubes

    Test tube rack

    5 labelled beaker for dispensing

    solutions

    5 5ml syringes

    Fresh potato

    Method

    1) Place 5 test tubes into a test tube rack

    2) Place 10ml of solution into the corresponding test

    tube relative to the solution in the beaker.

    3) Cut 5 cylinders of potato 3cm long about 8mm in

    diameter.

    4) Put a cylinder of potato into each test tube and start

    stopwatch

    5) After 5 mins, measure the height of the foam(oxygen)

    which forms

    Conclusion

    Changes in ph alter an enzymes shape. Each enzyme as an optimal ph.

    The ph can change in different parts of the body.

  • Change in substrate concentration Materials

    20 volume hydrogen peroxide

    Distilled water

    5 test tubes

    Test tube rack

    10ml pipettes

    Fresh potato

    Ruler

    Cork borer

    Method

    1) Set up 5 test tubes in a test tube rack

    2) Pipette the following amouns of hydrogen peroxide and water into each test tube:

    Test tube 1 2 3 4 5

    H2O2 (ml) 0 2.5 5 7.5 10

    Distilled water (ml) 10 7.5 5 2.5 0

    3) Mix the contents of each test tube

    4) Cut 5 cylinders of potato 3cm long about 8mm in

    diameter

    5) Put a cylinder of potato into each test tube

    6) Mark the height of the liquid in each test tube

    7) After 5 mins, mark and measure the height of the bubbles

    of oxygen that form over

    8) Record results

    Conclusion

    Increased substrate concentration will increase rate or

    reaction until another condition becomes a limiting factor.

    1.3 Identify pH as a way of describing the acidity of a substance: pH is a measure of the acidity of a substance

    1.4 Identify Explain why the maintenance of a constant internal environment is important for optimal efficiency:

    Enzymes control all the metabolic processes in the body

    Enzymes work optimally in an environment where their optimum temperature 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.

    E.g. If the process of respiration is disrupted, there will be a decrease in the release of

    energy and the body will not function properly.

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

    Homeostasis: the maintenance of a relatively stable internal environment.

    The process by which the internal environment is kept within normal limits regardless, of the

    external environmental conditions, e.g. Temperature, ph, gas levels, water and salt

    concentrations.

    Allows enzymes optimal conditions to be met and the body to work efficiently and kept as

    stable as possible.

    1.6 Explain that homeostasis consists of two stages: Detecting changes from the stable state Counteracting changes from the stable state

    For a state of homeostasis to exist the body must have some way of detecting stimuli that

    indicate a change in the bodys internal or external environment.

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

    The stimulus response pathway consists of the steps:

    Stimulus receptor central nervous system effector response This pathway in the nervous system allows a change in the environment to be detected

    and a response made to counteract the change.

    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 cord 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,

    temperature sensors in the skin detect the temperature change and a sensory neuron

    conducts a nervous impulse to the hypothalamus found in the brain. Nerve impulses pass

    this information from the receptors to effector neurons then onto effectors, such as blood

    vessels, sweat glands, endocrine glands and muscles.

  • 1.8 Gather, process and analyse information from secondary sources and use available evidence to develop a model of a feedback mechanism:

    Keeping Warm Keeping Cool

    Shiver to generate heat Sweating; evaporation loses heat

    Hair muscles erect; insulation Blood vessels dilate; increased

    blood supple, more heat lost

    Increased appetite Hair relaxes, less insulation

    Blood vessels constrict; less

    blood flow, less heat loss Decrease in metabolism

    Increase in metabolism Less exercise

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

    Ambient temperature is the temperature of the environment

    Organisms on earth life in environments with ambient temperatures ranging from less than

    0o (arctic animals) to more than 100o (bacteria found in boiling undersea volcano vents).

    But, individual organisms cannot survive this entire range of temperatures.

    E.g. Mammals can only survive temperatures from about 0-45o

    Below 0oc, cells risk ice crystals forming in them and above 45oc, proteins within cells may

    denature

    This means that life is found in a very wide range of temperatures, but individual species

    can only be found in a narrow temperature range

  • 1.10 Compare responses of named Australian ectothermic and endothermic organisms to change in the ambient temperatures and explain how these responses assist temperature

    regulation:

    Endotherms use internal metabolic processes to control their body temperature, e.g. Mammals

    and birds.

    Endotherm responses to changing temperature:

    o Migration: The short-tailed shearwater migrates to equatorial regions during the

    winter months. This is to avoid the cold weather, as the bird only breeds in warm

    weather.

    o Insulation: The superb parrot contracts the muscles controlling its feather in cold

    conditions, fluffing up its coat. This maintains a later of trapped air as insulation. This

    air reduces heat exchange with the environment.

    o Evaporation: The red kangaroo licks its arms to cool itself. The evaporation of the

    saliva cools its skin.

    o Nocturnal Behaviour: Hopping mice, and many other Australian endotherms, are

    nocturnal. This is to prevent overheating, and to reduce moisture loss.

    Ectotherms use the energy from their environment to regulate their body temperature, e.g. Fish,

    reptiles, amphibians.

    Ectotherm responses to changing temperature:

    o Controlling Exposure: The goanna controls its body exposure to the sun by sun

    baking in the cool morning, and staying in shade during the hot hours.

    o Hibernation: The Bogong moths hibernate in hot weather (this is called aestivation). During summer, they gather in caves, their metabolism slows and the

    body temperature drops. This is to maintain body temperature.

    o Shelter: The central netted dragon stays in sheltered areas to avoid extreme heat.

    They can dig burrows or seek shelter in caves or crevices. This reduces the effect of

    heat on their body.

    o Nocturnal Activity: Brown snakes can change into nocturnal animals when the

    temperature becomes very hot. Many desert animals sleep in burrows during the

    day and are active at night, to escape the heat.

    1.11 Analyse information from secondary sources to describe adaptations and responses that have occurs in Australian organisms to assist temperature regulation:

    Organism Endo/Ecto Adaptations

    Thorny Devil Ectotherm

    Burrows into sand to avoid heat at midday

    Water can be directed from anywhere on body to

    mouth for cooling and water absorption.

    Crocodilians Ectotherm Various basking behaviours.

    Mouth gaping, body orientation in regards to the sun

    Blue tongue

    lizard Ectotherm

    Basks in sun

    Inactive during hot days

    Red

    Kangaroo Endotherm

    Licks paws

    Sits in shade

    Sweats to cool

    Alpine pigmy

    possum Endotherm

    Sleeps in tightly would ball to retain heat

    Huddling with other individuals to keep warm

    Platypus Endotherm

    Goes through periods of hibernation

    Has an insulating coat that retains heat when

    swimming in cold water

    Have sweat glands in important areas to cool

    organism during hot weather.

  • 1.12 Identify some responses of plants to temperature changes: Plants respond to temperature change by altering their growth rate E.G. Some Eucalyptus

    trees grow more in spring than in winter.

    In extreme heat or cold, plants can die, but leave behind dormant seeds.

    Plants may die above the ground, but leave bulbs, roots, rhizomes or tubers to survive

    underground. These then sprout when favourable conditions return

    Some plants can change the orientation of their leaves in relation to the sun at different

    times of the sun, thus controlling temperature

    Leaves hang down vertically to reduce sun exposure

    2.1 Identify the forms in which each of the following is carried in mammalian blood:

    Substance Form carried in mammalian blood

    Carbon Dioxide

    Enters red blood cells and is combined with water to form

    bicarbonate ions (HCO3-)

    7% Co2 dissolved in plasma

    23% combines with haemoglobin forming carbaminohaemoglobin

    70% forms hydrogen carbonate ions and travels in plasma

    Oxygen Oxygen combines itself with haemoglobin to form

    oxyhaemoglobin in red blood cells (hbo2)

    Water Liquid water is the solvent making up 90% of the plasma.

    Salt Salt travels as either positive or negative ions in the plasma

    Lipids Lipids are carried with phospholipids and cholesterol in a protein

    coated package called a chylomicron.

    Nitrogenous

    Waste

    The nitrogenous waste is ammonia, but as this is toxic mammals

    convert this to urea. Conversion occurs in the liver and the kidney

    filter the urea from the blood.

    Urea is transported dissolved in the plasma

    Other products

    of digestion

    Many other products are soluble and travel in the plasma, e.g.

    Sugars, amino acids, vitamins

    2.2 Explain the adaptive advantage of haemoglobin:

    Oxygen is not very soluble in water and cannot be

    carried efficiently dissolved in blood plasma.

    The red blood cell has no nucleus; therefore it can carry

    as many haemoglobin molecules as possible.

    The haemoglobin is a complex protein molecule (3D)

    which is made up of 4 long amino acid chains, each one

    assembled around the atom of iron. Iron easily combines

    with oxygen.

    Adaptive advantage of haemoglobin is that it increases

    the bloods carrying capacity of oxygen. Resulting in more oxygen available for cells.

    Therefore gives an organism the ability to become more complex.

    Mammalian cells need a lot of energy and therefore must have a continual supply of

    oxygen for respiration

  • 2.3 Compare the structure of arteries, capillaries and veins in relation to their function:

    Feature Arteries Capillaries Veins

    Definition Carry blood away from the

    heart

    Thin-walled blood vessel

    linking arteries and veins Carry blood to the heart

    Structure

    Thick elastic muscular

    walls

    Smooth inner layer

    3 main layers with muscle

    and elastic tissue

    A single layer of flat

    overlapping cells

    No elastic or muscular

    fibres

    Thinner muscular walls

    Wider diameter

    Valves

    Fewer elastic and muscle

    fibres.

    Function

    Distribute blood away

    from the heart, e.g. To

    arterioles that carry blood

    to capillaries

    Cope with high pressure

    of blood being pumped

    Enables expansion and

    contraction to adjust to

    the amount of blood

    flowing through at any

    one time

    Carry oxygenated blood

    (except pulmonary artery)

    Allows red blood cells to

    pass through, maximising

    the chance for the gases,

    nutrients and wastes

    between the blood and

    the tissue cells.

    This way the bodys tissues are efficiently supplied

    with the substances they

    need while wastes are

    removed

    Gas exchange occurs,

    e.g. Oxygen from blood

    into tissues

    Return blood to the heart

    from capillaries to venules

    to veins

    Allows increases amounts

    of blood flow through

    veins

    Prevent blood flowing

    backward in the vein by

    valves

    Carry deoxygenated

    blood (except pulmonary

    vein)

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

    The chemical composition of blood changes as it moves around the body. This is as a result

    from the continuous exchange of substances between the blood and the surrounding

    tissues.

    In general, blood moving through the bodys tissues delivers oxygen and glucose for cellular respiration as well as nutrients.

    In general, blood moving away from the bodys tissues carries carbon dioxide and nitrogenous wastes for disposal.

    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

    2.5 Performa first-hand investigation to demonstrate the effect of dissolved carbon dioxide on water:

    Materials

    Straw

    100ml distilled water

    Universal indicator colour chart OR Probe for more accurate or fast results

    Beaker

    Method

    1) Pour 100ml of distilled water into a beaker

    2) Grab the straw and place in beaker

    3) Blow gently avoiding spillage

    4) Blow for two minutes

    5) Observe colour change and check the ph by comparing to the universal colour chart OR

    using data loggers with a ph probe.

    Conclusion

    The water turned a yellow colour as our breath contains carbon dioxide.

    The carbon dioxide dissolved in the water and some of it formed carbonic acid

    The formation of acid lowers the ph.

  • 2.6 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 for each:

    Materials

    Light microscope

    Ruler

    Prepared blood slide

    Mm squared graph paper

    Method

    1) Set up the light microscope.

    2) Place a small piece of mm squared paper. View the paper using a x40 objective.

    3) Measure field of view by counting amount of squares across.

    4) Remove the grid and place the prepared blood slide under the microscope.

    5) Count the number of red blood cells across the field of view.

    6) Record results.

    Conclusion

    Red blood cells (erythrocytes):

    Size: 6-9 m

    Shape: Bi-concave discs

    Function: Transport of oxygen.

    They have no nuclei; they only live for 3 months.

    After this they are destroyed in the liver or spleen.

    5-6 million in every millilitre of blood.

    They are produced in the bone marrow

    White blood cells (leucocytes):

    Size: 12-15 m

    Shape: Irregular shape; can change shape

    Function: To defend against disease

    Only 4-12 thousand per millilitre of blood

    They are the largest blood cell

    They have nuclei, unlike red blood cells

    They are produced in the lymph glands.

    2.7 Outline the need for oxygen in living cells and explain why removal of carbon dioxide from cells is essential:

    All living things use the process of respiration to release energy to be used by cells to

    maintain life processes. Aerobic respiration uses oxygen in the equation:

    GLUCOSE + OXYGEN CARBON DIOXIDE + WATER + ENERGY Cell respiration is essential as it provides energy that is needed for metabolic process (e.g.

    Protein synthesis) and if these processes do not occur it can result in fatality.

    As a result of respiration, carbon dioxide is produced

    When carbon dioxide dissolves in water, it makes carbonic acid.

    This means that if a lot of carbon dioxide is produced, the body cells (and the blood and

    lymph) will become acidic.

    As studied before, enzymes can only function within a specific ph range

    So an increase in carbon dioxide will result in a lowering of ph, which will affect the overall

    metabolism of the body.

  • 2.8 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:

    Measuring oxygen saturation levels:

    Pulse Oximetry

    Newer method

    Non-invasive and

    Can be used continuously on patients when needed such as in the intensive care

    unit

    Simply, passes two wavelengths of light through the finger and then measures the

    amount of absorption on the other side.

    This can determine the saturation levels of haemoglobin and hence the oxygen

    levels

    Measuring carbon dioxide concentrations

    Capnometer

    Non-invasive technique

    Can be used continuously if needed

    An infrared beam is passed through the blood and the absorption amount is

    measured to determine the levels of carbon dioxide.

    Measuring oxygen & carbon dioxide

    Arterial Blood Gas Analysis (ABG):

    A test that can be invasive

    But, delays between the test and the result.

    Needs only a sample of blood from an artery and can help with distinguishing

    between conditions with similar symptoms

    Used to determine the concentration of oxygen and carbon dioxide and the ph

    level in the blood.

    E.g. A patient in a coma can have their blood gases regularly monitored

    2.9 Analyse information from secondary sources to identify the products extracted from donated blood and discuss the uses of these products:

    Red blood cells:

    o Used to increase the amount of oxygen that can be carried to the bodys tissues; o Given to anaemic patients, or people whose bone marrow do not make enough

    red blood cells

    Platelets:

    o Used to make the blood clot; is given to people with cancer of the blood

    (leukaemia or lymphoma).

    o Patients undergoing chemotherapy, whose blood does not make enough platelets,

    are given this.

    Plasma:

    o This liquid portion of the blood is given to people with clotting disorders (such as

    haemophilia).

    o It carried dissolved nutrients such as glucose, amino acids and blood cells and is

    important in the treatment of burn victims.

    o Also used to adjust the osmotic pressure of the blood (to pull fluids out of tissues).

    White blood cells:

    o Infection fighting component of the blood.

    o Very rarely given, but are used when cell count is very low.

  • 2.10 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 is a term to describe man made products that fulfil some of the functions of biological blood.

    Problems using real blood

    o Shortage of real blood

    o Has to be cross matched, because if you receive the wrong type of blood it can be fatal, which is a disadvantage in emergency.

    o Free of infectious agents.

    Why artificial blood is needed

    o The amount of blood needed for transfusion is rising each year faster than the

    amount of blood being donated.

    o Also chance in some places around the world of undetected blood bank

    contamination from AIDS, hepatitis C and other diseases.

    o In emergency trauma situation, e.g. Battlefield, there is need for rapid treatment of

    patients without determining blood type for immunologic reactions as blood

    substitutes do not contain any antigens.

    o Blood has storage problems it must be kept at 4 degrees and only stays fresh for 42 days.

    Advantage of artificial blood

    o Free of infectious diseases

    o Does not need refrigeration

    o Can be kept for a longer period of time, e.g. 2-3 years unlike 3 weeks for human

    blood

    o Universal acceptance by all groups

    o Readily available in large supplies solving problem of blood donors

    2 types of Oxygen Carriers

    1. Perflurochemicals (perflurocarbons):

    o Synthetic and inert, are completely sterile

    o Cheap to produce, compared to using real blood.

    o Can dissolve 5 times more oxygen than blood.

    o Free of biological materials, therefore no risk of infections

    o BUT - must be combined with other materials to mix in with the bloodstream (e.g.

    Lecithin).

    2. Haemoglobin Based Oxygen Carriers (hbocs):

    o Made from haemoglobin extracted from red blood cells

    o Haemoglobin is not contained in membrane - cross matching unnecessary

    o Can be stored for a long time

    o BUT - haemoglobin tends to oxidise to a different form, break down, and can no

    longer carry oxygen.

  • 2.11 Describe current theories about processes for the movement of materials through plants in xylem and phloem tissues:

    Xylem (Transpiration-Cohesion-Tension Mechanism)

    Xylem cells are not alive, so physical processes are responsible for the upward movement

    of water and minerals.

    Theory:

    o Cohesion: water molecules stick together.

    o Transpiration: Water is pulled up from the top.

    o Tension: Water moves up the xylem like a wire, due to cohesion.

    o Adhesion: When the pull stops (at night) water sticks to the sides of the tubes and

    doesnt fall down. 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. This is

    passive transport.

    Phloem (Pressure Flow Mechanism/Source to Sink)

    The sugar is loaded into the phloem tube from the sugar source, e.g. The leaf (active

    transport)

    Water enters by osmosis due to high solute concentration in the phloem tube. Water

    pressure is now raised at this end of the tube.

    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.

  • 2.12 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:

    PHLOEM:

    XYLEM:

  • 3.1 Explain why the concentration of water to cells should be maintained within a narrow range for optimal function:

    Water inside a cell is essential for life. Too little or too much can result in serious problems

    and most cells will die if their water content is changed significantly.

    It is necessary for many reasons:

    o It is the medium that transports and distributes many substances (such as nutrients

    and wastes) in and between cells.

    o It is the solvent in which many important ions and molecules required for metabolic

    reactions are dissolved. They are only able to move when in aqueous solution as can

    they diffuse across and between cells.

    o Metabolic reactions that occur within cells can only occur in solution.

    o Water itself is a reactant or product of many cellular reactions e.g. Cellular

    respiration

    For optimal functioning of cells it is reliant on their water content being kept within a very

    narrow range. The concentration water inside the cell (intracellular fluid) must match the

    concentration of water outside the cell (interstitial fluid). This is called isotonic.

    If these concentrations do not match, water will move by osmosis from the area of higher

    concentration to lower concentration. This leaves cells venerable to losing or gaining to

    much water.

    Cell metabolism is controlled by enzymes.

    Each enzyme requires specific conditions for optimal efficiency, e.g. Specific ph, temp., ion

    concentrations.

    A change in the concentration of water in cells could interfere with the functioning of

    enzymes and metabolism would be disrupted.

    3.2 Explain why the removal of wastes is essential for continued metabolic activity: Cells are the site of many metabolic reactions.

    These metabolic activity keeps the cell functioning

    Many metabolic reactions produce wastes that if left to accumulate, would poison and

    eventually kill the cell.

    Like carbon dioxide other waste products are to be removed for example, excess salts,

    excess water and nitrogenous wastes.

    Waste accumulation is toxic and can disrupt metabolic activity, e.g. High levels of

    ammonia or urea will kill cells and excess water will change concentrations affection

    enzyme activity.

    Carbon dioxide is removed in air exhaled by lungs

    Nitrogenous wastes removed in urine produced by kidneys.

  • 3.3 Identify the role of the kidney in the excretory system of fish and mammals: The primary role is osmoregulation.

    This is the regulation of salt and water levels in the body

    Freshwater Fish

    o The kidney is an excretory organ that filters blood and

    removes nitrogenous wastes.

    o High filtration rate

    o Produces large amount of very dilute urine as water tends

    to enter the fish via osmosis

    Saltwater Fish

    o The kidney is an excretory organ that filters blood and

    removes nitrogenous wastes.

    o Low filtration rate

    o Small quantity of concentrated urine produced as water

    tends to leave the fish via osmosis

    Mammals

    o The kidney is an excretory organ that filters blood and removes nitrogenous wastes.

    o Has many nephrons

    o High blood pressure in glomerulus forces ultra filtration

    o Amount and concentrations of urine depends upon water intake and activities

    Birds

    o Excretes nitrogenous wastes in the form of uric acid

    o This white paste help to conserve water

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

    Osmosis: The tendency of water to pass through a semi-permeable membrane into a

    solution where the solvent concentration is higher, thus equalizing the concentrations of

    materials on either side of the membrane.

    Diffusion: The spreading of something more widely.

    Diffusion and osmosis are both examples of passive transport, and will not occur unless a

    sufficient concentration gradient is present.

    Diffusion is too slow for the normal functioning of the body and is not able to selectively

    reabsorb useful solutes.

    Osmosis only deals with the movement of water and thus would only allow water to move

    out of the body, not the nitrogenous wastes.

    In the kidney, some useful products are reabsorbed into the body this would not be possible with diffusion (active transport needed).

    Osmosis without active reabsorption of water would result in excess water loss.

    The kidney functions by using excreting all the blood substances in the nephron outside the body and then selectively (actively) reabsorbing useful materials.

  • 3.5 Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney:

    Active transport requires an input of energy for the movement of materials across a cell

    membrane.

    Passive transport does not require an input of energy for movement across a membrane,

    e.g. Osmosis and diffusion.

    In the mammalian kidney, both active and passive transport processes occur.

    o Passive transport: Once filtration has occurred in Bowman's capsule, water returns

    via the interstitial fluid from the tubule to the capillary in the process of osmosis. This

    occurs along the length of the tubule.

    o Active transport: Depending on their concentration, the ions in the blood (Na+, K+,

    Cl- , H+ and HCO3) can be transported to cells in the nephron tubule and then

    secreted by the cells into the tubule. Some poisons and certain drugs are eliminated

    from the body in this manner.

    3.6 Explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition:

    Filtration and reabsorption are the processes that

    perform the complex balancing of retaining essential

    substances and removing wastes from blood.

    Ultrafiltration occurs when high blood pressure in the

    glomerulus forces water ions and small molecules into

    Bowmans capsule. By filtration, substances are removed from blood if

    they are small enough to be forced through the

    membrane of Bowmans capsule. Blood cells and proteins are too large to be removed.

    This filtering process is non-selective and therefore

    many valuable components of the blood must be

    recovered by reabsorption.

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

    Materials

    Sheep/lamb kidney

    Dissecting board

    Scalpel

    Rubber gloved

    Newspaper

    Magnifying glass

    Probe

    Method

    1) Observe the outer shape of the kidney and the capsule.

    2) Identify the tubes entering the kidney ureter, renal artery and renal vein use the magnifying glass to check the thickness of the walls of the blood vessel.

    3) Cut the kidney lengthwise using the scalpel.

    4) Use the magnifying glass to observe the internal structure

    of the kidney and draw observations.

    5) Use the probe to follow the pathway from ureter into

    pelvis of kidney.

    6) Record observations

    7) Draw a labelled diagram of observations

    8) Wrap the dissected kidney in newspaper and dispose of it appropriately.

    Safety

    Be careful when using the scalpel as the blade could cut skin leading to potential

    infection.

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

    Kidney Renal Dialysis

    Removes waste from blood Removes waste from blood

    Natural process Artificial process

    Continuous removal of wastes Removes wastes only when patient is

    hooked up to the dialysis machine

    Rapid process Slow process

    Uses passive & active transport Depends on passive transport only

    Uses filtration & reabsorption Uses filtration only

    Main filter is glomerulus Filter is dialysis tubing

    Wastes & some metabolites are removed in

    filtration

    Wastes & water removed in filtration,

    metabolites stay in blood

    Internal process Usually external

    Urination occurs Some to No urination occurs

  • 3.9 Outline the role of the hormones, aldosterone and ADH (antidiuretic hormone) in the regulation of water and salt levels in blood:

    Aldosterone:

    Produced and released by the adrenal glands, which sit above the kidneys.

    Controls the amount of salt in the blood by regulating the reabsorption of salt in the

    nephrons.

    High Salt Levels:

    o High blood volume and blood pressure due to water diffusing in.

    o Levels of aldosterone decreased.

    o Less salt reabsorbed, less water diffusing in

    o Salt level decreased, blood volume and pressure decreases

    Low Salt Levels:

    o Low blood volume and blood pressure due to water diffusing out.

    o Levels of aldosterone increased.

    o More salt reabsorbed, more water diffusing in

    o Salt levels increase, blood volume and pressure increase

    ADH (Anti-Diuretic Hormone):

    Also called vasopressin

    Controls the reabsorption of water by adjusting the permeability of the collecting ducts

    and the distal tubules.

    It is made in the hypothalamus in the brain, but stored in the pituitary gland

    Receptors in the hypothalamus monitor the concentration of the blood:

    o High Salt Concentration: ADH levels increased, collecting ducts and distal tubules

    become more permeable to water, more water reabsorbed, concentration returns

    to normal. (Concentrated urine)

    o Low Salt Concentration: ADH levels reduced, collecting ducts and distal tubules less

    permeable, less water absorbed, concentration returns to stable state. (Dilute urine)

    ADH does not control the levels of salt in the blood. It only controls the concentration of salt

    through water retention.

    3.10 Present information to outline the general use of hormone replacement therapy in people who cannot secrete aldosterone:

    Hormone replacement therapy: a treatment given when a gland is not producing enough

    of a particular hormone.

    The adrenal gland secretes aldosterone.

    Without aldosterone, the body would not be able to reabsorb salt (specifically sodium ions)

    and this would cause severe dehydration, and excessive potassium.

    This would result in brain damage and death

    Fludrocortisone is an artificial hormone which can be used as a treatment for people who

    cannot secrete aldosterone (due to a damaged adrenal gland; Addisons disease). It does the job of aldosterone.

  • 3.11 Analyse information from secondary sources to compare and explain the differences in urine concentration of terrestrial mammals, marine fish and freshwater fish:

    Urine Terrestrial mammal Saltwater fish Freshwater fish

    Concentration of urine

    Concentration varied

    greatly depending on

    environment and

    water availability

    Concentrated urine Dilute urine

    Amount of urine

    released

    Amount varies greatly

    depending on

    environment and

    water availability

    Very little urine

    produced

    Copious amounts of

    urine produced

    Reason for amount

    and concentration

    Water availability on

    land depends on the

    ecosystem. Rainforests

    has abundant water,

    while deserts have

    limited water

    Body solute

    concentration is less

    than the surrounding

    environment, so water

    moves out of the fish

    by osmosis

    Body solute

    concentration is

    higher than the

    surrounding

    environment, so water

    moves into the fish by

    osmosis

    3.12 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:

    Ammonia

    o Is very toxic.

    o Must be excreted immediately and in a dilute form.

    o Commonly secreted by aquatic invertebrates and fish that live in freshwater where

    the availability of water is not a limiting factor.

    Urea

    o Most common form of nitrogenous waste excreted by terrestrial mammals.

    o Not as toxic as ammonia and can be excreted in a less dilute form, resulting in less

    water loss.

    o But, requires more energy for its production.

    Uric Acid

    o Least toxic form of nitrogenous waste means it can be secreted with minimal water

    loss.

    o Excreted as a semi-solid, whitish paste to help conserve water.

    o Uses a lot of energy to be mad, but has the smallest amount of water loss.

  • 3.13 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.

    In an environment such as an estuary where the salt and water concentrations rise and fall,

    the survival of the species depends on their ability to either AVOID these changes or

    TOLERATE them.

    One example of enantiostasis is when a change in salt concentration in the body fluid,

    which reduces the efficiency of an enzyme, is compensated for by a change in pH, which

    increases the efficiency of the same enzyme.

    In an estuary the daily changes in tides affect the salinity of the environment in the

    following ways:

    o At high tides: sea water flows into the river mouth creating an environment with

    higher salt concentrations than the cytoplasm of cells and body fluids in organisms.

    This salt water has tendency to draw water out of the cells by osmosis.

    o At low tides: sea water flows out of the river mouth and fresh water flows in. Plants

    and animals which are subjected to this freshwater environment with a high water

    potential face the challenge of water tending to move into living tissue.

    Living organisms use one of the following strategies in enantiostasis:

    Osmoconformers Osmoregulators

    Organisms that tolerate the changes in the

    environment.

    Organisms that avoid changes in their internal

    environment

    They modify the salt concentration in their

    body to match fluctuations in external

    conditions.

    They maintain a constant salt concentration

    in their despite environmental fluctuations.

    Metabolism and cell functioning are able to

    continue within a broad range of salinity.

    Their cell metabolism and physiology is not

    able tolerate a range of salt concentrations.

    Mechanism: they use small organism

    molecules to vary the solute concentrations in

    their cells to match that of the surroundings.

    Mechanism: their body fluids are similar to

    those in a marine environment, so when

    exposed to freshwater, the water tends to

    accumulate by osmosis. To counteract the

    changes, the animal produces more dilute

    urine to reduce the internal water

    concentration to a level at which cells can

    function

    Result: The osmotic pressures inside the body

    and outside the body are the same.

    Result: A higher osmotic pressure is

    maintained inside the body than in the

    external environment.

  • 3.14 Process and analyse information from secondary sources and use available evidence to discuss processes used by different plants for salt regulation in saline environments:

    Plants that are adapted to saline environments are called halophytes.

    The plants either use salt tolerance or salt avoidance as strategies to survive in

    environments where they are exposed to high salt concentrations

    Examples of halophytes:

    Saltbush:

    o Is an excluder it actively transports excess sodium and chloride ions into bladder cells situated on the tip of hairs on the surface of leaves.

    o When the bladder cell reaches capacity it bursts, releasing the salts into the

    environment.

    Palmers grass:

    o Actively secretes salts from specialised cells to avoid high salt concentration within

    cells.

    Succulents:

    o Minimise the salt toxicity through increasing water content in large vacuoles, where

    the accumulation of excess salt is balanced with additional water drawn into the

    cells.

    Pickleweed:

    o Uses the above method and also actively transports salts from the cytoplasm by a

    sodium potassium pump on the vacuole membrane. Pigface:

    o A succulent that grows on coastal sand dunes, tolerates salt by increasing water

    uptake to dilute the salt.

    o It also stores excess salt in a location away from sensitive cells.

    Mangroves:

    o Survive in high salt concentrations by means of exclusion, secretion and

    accumulation.

    o Special tissues in their roots and lower stem exclude salt uptake but allow water to

    pass through.

    o Secretion occurs as salt can be concentrated and then excreted through special

    glands within their leaves.

    o Salt is accumulated in older tissues, such as leaves and branches which are then

    discarded.

    3.15 Describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss:

    Plant Feature How feature minimises water loss

    Spinifex grass Leaf can coil around

    underside

    Stomates on underside are protected

    from, wind etc and water loss by

    transpiration is reduced.

    Hakea Multilineata

    (Grass Leaf hakea)

    Leaves are long, thin

    blades

    Long, thin blades reduces SA:V. This

    reduces water loss by transpiration.

    Carpobrotus Rossii

    (Pigface) Leaves are thick, succulent

    Thick, succulent leaves store water

    allowing plants to grow in arid areas and

    have water available when needed.

    Actinotus Spp (Flannel

    flower)

    Leave have dense

    covering of pale woolly

    hairs

    Dense covering of woolly

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

    Materials

    A variety of plant species

    Plant identification book

    Pencil

    Magnifying glass

    Microscope

    Method

    1) Analyse the plant material provided to identify the structures present that assist with

    minimising water loss.

    Results (structures and features in plant to help reduce water loss)

    Wide dense root network to obtain as much water as possible

    Succulents store water in stems, leaves or trunks

    Leaves have reduced SA

    Sunken Stomates create a humid environment outside the pore

    Thick waxy cuticle prevent water loss and maintain leaf shape even if cells are dehydrated

    Reduced flower size or flowers with no petals