ROSE CLARKE- BIOLOGY NOTES Maintaining a Balance

1. Most organisms are active in a limited temperature range x Identify the role of enzymes in metabolism, describe their chemical composition and use a

simple model to describe their specificity to substrates

Enzymes:

Chemical Composition: x Enzymes are globular proteins made up of long chains of amino acids

o Proteins are large, complex macromolecules, built from a linear sequence of amino acids. As enzymes they control the metabolic reactions of cells

o Cofactors are a non protein component of an enzyme and may be an inorganic molecule. Often added component of enzyme to complete catalytic properties. Prosthetic groups (permanent) or coenzymes (temporary)

o Amylase acts of starch to create glucose .

x The part of the enzyme surface which the substrate is bound and undergoes the reaction is known as the active site.

o Catabolism single substrate molecule to be drawn into active site , breaking chemical bonds, breaking substrate into 2 separate molecules.

o Anabolism two substrate molecules are drawn into active site, chemical bonds form single molecule

Role x Increase rate of reaction without a change in temperature x Lower the activation energy by bringing substrate specific molecules together rather than

random collision x Act of specific substrate x Chemically unchanged but can be reused x Biological catalysts

LOCK AND KEY MODEL or Induced-Fit Model

Giorgia Watts

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

x The pH scale is used to measure the acidity or alkalinity of a substance x Is a logarithmic value of the concentration of [H+] ions in solution

o Greater log value the lower the pH x The presence of hydrogen ions in solution makes it more acidic

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

metabolic efficiency

x All chemical reactions within cells must occur efficiently and be effectively co ordinate to bring about optimal metabolic efficiency.

x Enzymes are extremely sensitive to changes in their internal environment (intercellular or interstitial fluid and cytoplasm) and any imbalance can adversely affect their function

x Internal environment of an organism must be maintained within a narrow range of conditions (temp, volume, chemical contents) so that enzymes can function effectively and metabolic efficiency can be maintained.

o Metabolic efficiency relies on temp/pH, concentration of metabolites, water and salt concentration and absence of toxins that may inhibit enzyme to Regulate respiratory gases, Cope with disease and pathogens, Maintain nutrient supply and Repair injury

Importance Experiments which affect activity of enzyme x pH and temp

o enzymes only function in a narrow temp and pH range; outside these ranges enzymes decrease in activity or denature rendering non functional reducing metabolic efficiency

x Metabolites o Chemicals that

1. increased temperature - Risks: hydrogen peroxide is hazardous if swallowed,

irritant to eyes, hot plates are at high temperature so can burn

1. 5 water baths at different temperatures (independent variable) (5,25,39- control,80,100)

2. Add 5 identical pieces of liver (controlled variable) (enzyme) into each test tube

3. Add 5ml of Hydrogen peroxide into separate test tubes

4. Place test tubes into water baths for 2 mins (controlled variable) and pour the two test tubes together

participate in chemical reactions in cells. Some are taken from outside while others are products of metabolic pathways, e.g. ATP. Metabolic reactions rely on energy, thus a lack of metabolites can slow down or stop cellular respiration and affect overall metabolic efficiency.

x Water and Salt concentration

o Reactants in chemical reactions need water while dissolved salts affect the osmotic balance of fluids and so concentration of salts ect must be maintained in narrow range.

x Absence of toxins o A build up of CO2 or

other wastes as a product of cellular reactions may be toxic, affecting enzymes directly by blocking active site or indirectly by altering the optimal conditions of enzymes.

5. Measure height of the foam in each and repeat / average results

- High temperatures decrease activity as enzyme is denatured, Low temperatures decrease activity as kinetic energy is lower

2. Change in pH - Risks: hydrogen peroxide is hazardous if swallowed,

irritant to eyes 1. Add 1ml of acid into 4 test tubes using pipette each

with different pH level (independent variable), (a-ethanoic acid, b-distilled water, c-tap water, d-sodium carbonate)

2. Add 1ml of potato solution, and mark the height 3. Add 1ml of hydrogen peroxide solution and time for

30 seconds 4. Measure the height of the bubbles and repeat,

record results (dependent variable) - Activity decreased either side of optimum as

enzymes were denature

3. Change in substrate concentrations - Risk: hydrogen peroxide is hazardous if swallowed,

irritant to eyes (substrate) 1. 6 test tubes, with increasing amounts of hydrogen

peroxide (independent variable) and increasing amounts of distilled water into each

2. Add 1ml of potato solution to each and record the top of the mixture

3. Time for 1 min, measure the height of the bubbles (dependent variable) and record/ repeat results

- Height of bubbles increased as substrate concentration increased until saturation point

- Control was test tube a with no hydrogen peroxide - Controlling variables- amount of enzyme, time, pH,

temperature

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

Homeostasis is the process by which organisms maintain a relatively stable constant internal environment, regardless of the external environmental conditions.

Stimulus receptor brain (CNS) effector response

x To maintain homeostasis organisms must detect stimulus from both internal and external environments then counteract the change.

x It is vital for survival of all cells as all the chemical processes function within a narrow range of conditions.

x It maintains optimal metabolic efficiency.

Note: Body temperature in mammals is a homeostatic mechanism. To reduce temperature, heat can be expelled by sweating or radiation of heat from the skin. To increase heat, the body can respond by shivering or by contracting the skin. These responses can be activated by heat receptors. If a mechanism is activated, it will operate until receptors indicate that the optimum temperature has been reached.

x Explain that homeostasis consists of two stages:

o Detecting changes from the stable state o Counteracting changes from the stable state

Homeostasis involves coordination, control and maintenance of stable internal environment. In mammals, nervous and endocrine systems are involved.

x Variables within internal environment have a set point. If the fluctuation of these variables is large, the stimuli is detected by receptors and a negative feedback mechanism operates to counteract the change, returning body to homeostasis.

1. Detecting changes

x Sensory cells or receptors detect change in temp or chemical composition x Called stimuli

2. Counteracting changes

x Effector organs (such as muscles or glands) respond to change and counteract it to return to homeostasis.

Model for Negative Feedback Mechanism:

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

changes

The nervous system consists of Central Nervous System (CNS) [brain and spinal cord] and Peripheral Nervous System (PNS) [sensory nerves and effectors nerves]

- The nervous system detect changes, sending neuron messages to the hypothalamus in the brain to respond to the changes and ensure homeostasis is maintained

Receptors: x Rods and cones in the retina detect light x Hair cells in the cochlea of the ear that detect pressure waves in the cochlea fluid x Taste buds on the tongue x Olfactory receptors in nose x Mechanoreceptors, thermo receptors, pain receptors in skin

Endocrine system: consists of endocrine glands which produce hormones into the bloodstream. Chemical message which travel through the blood, so take longer to act than nerves but their effects are longer lasting.

x Identify the broad range of temperatures over which life is found compared with the

narrow limits for individual species

Broad Range: - 70 degrees to 350 degrees

Narrow Limits: Individual Species

- Tolerance Range- optimal range of temperatures o Degree to which an organism can tolerate and survive in variation in environmental

factors - Chemical reactions that occur in cells take place only within a relatively narrow range of

temperatures, due to the temperature sensitivity of enzymes o If temperature increases- enzymes begin to denature as the weak hydrogen bonds in

enzymes break and change the shape of active site

- Examples: Submarine hydrothermal vents, can reach 350 degrees. o the hydrothermophilic microbe, Pyrolobus fumarii. o Pompeii worm

- Extreme cold o Microbes such as bacteria, lichen and fungi- a range of -17 to 20 degrees o arctic fox can withstand temperatures of -70 degrees.

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

The ambient temperature is the temperature of the environment the air, water in the immediate surroundings on an animal.

Ectothermic: Organisms that depend on an external source the environment for heat energy

Endotherm: Remains relatively stable despite the environment, but varies metabolism.

Habitat and optimum temperature range

Adaptations Comparison of responses

Endotherms- Red Kangaroo

Desert woodlands and open plains

larger surface area enables the kangaroo to maintain and lose body heat during periods of high temperatures. dense network of blood vessels particularly in their forearms. These blood vessels dilate when the ambient temperature is high. This dilation increases blood flow to the forearms and promotes heat loss. To increase cooling kangaroos lick their forearms. Kangaroos cool themselves by sweating. This evaporation of the water cools the organism down. However in times whereby the kangaroo needs to conserve water it will increase its body temperature a couple of degrees in order to maintain water. Kangaroos fur has two main processes when the ambient temperature increases/decreases. When the temperature decreases the fur stands on end in order to reduce heat loss and maintain body heat. When the ambient temperature increases the fur insulates the kangaroo from the hot air surrounding it. Kangaroos regulate their metabolic rates in order to regulate their body temperature. This is done by remaining crouched in the shade during times of extreme heat.

Has a steady internal core temperature, the metabolic rate is maintained at a high level as it gains its source of body heat internally.

Endotherm-

Fairy penguin

Coastlines, cold icy locations

- Feathers which trap air to reduce heat loss by acting as an insulator

- In low temps, the feathers are further away from skin to trap the maximum amount of heat

- In high temps, the feathers are flatter on body to reduce the

insulation, also move to water to cool body down

Ectotherms-

Frilled neck lizard

Hot tropical climates- dry forests and woodlands

Frilled neck lizards will flatten their body to absorb as much sun as possible in order to increase their body temperature. Frilled neck lizards will narrow their body if the ambient temperature is too high or if their own body temperature is too high. This is performed in order to reduce their surface area. Frilled neck lizards move into shades or burrows to cool down from the rising ambient temperature. The temperature in burrows is fairly constant, which enables the lizard to cool down. Burrows in particular also minimise water loss which is beneficial to the lizard. Due to the ambient temperature being too cold frilled neck lizards can go into a state of torpor whereby their body shuts down for the winter and their metabolic rate is slowed.

Dependent on the exterior hot climate in order to regulate body temperature.

Varies dramatically depending on the ambient temperature

Ectotherm-

Eastern brown snake

Dry desert areas in australia

- In hot temperatures, becomes active at night whilst sheltering during the day

- In low temps, the snake basks in sunlight to gain additional heat- becomes less active by slowing down metabolism.

- If long periods of low temperatures, hibernates in a well sheltered spot to retain stored food

x Identify some responses of plants to temperature change

Maintenance of a relatively stable internal environment is vital for plant metabolism.

Response to high temperatures

- Temperatures above 40 may cause damage to proteins and those above 75 to chlorophyll pigment within the plant. These responses are mostly structural and physiological

Evaporative cooling (transpiration)

o Causes the stomata in plants to open, leading to the loss of water via transpiration. This in turn decreases the internal temperature

o However this can cause dehydration of the plant, so excessive heat causes the stomata to close to preserve water

Turgor response (wilting)

o Reduce the exposure of their surface area to the sun and its associated heat and light.

o In extreme heat, the plants transpire and lose turgor in the palisade cells of leaves, resulting in leaves wilting, reducing SA. If water is available, wilting is temporary, however if not then wilting will lead to death. Many introduced plants do not have the adaptations for the dry climate such as hydrangeas and roses.

Leaf orientation

o Some leaves can hang vertically downward in hot temp to reduce surface area

Leaf fall- eg. eucalypts

Reseeding and resprouting in response to extreme high temperatures - fire eg. eucalypts

Thermogenic plants eg. lotus bud

Response to cold temperatures

- Organic anti freeze - eg. Antarctic hairgrass plant

o Substance that reduces the temperature at which the cytoplasm or cell sap in the vacuole freezes

- Dormancy eg. deciduous beech tree

o Deciduous trees lose their leaves in winter and undergo a period of dormancy, which allow them to survive, storing water and lower availability of sunlight

- Vernalisation eg. tulip buds

o Flower, e.g. tulip bulbs

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

2. Plants and animals transport dissolved nutrients and gases in a fluid medium

x Identify the forms in which each of the following is carried in mammalian blood: o Carbon dioxide o Oxygen o Water o Salts o Lipids o Nitrogenous waste o Other products of digestion

Substance Form carried in mammalian blood Carbon dioxide x 70% transported in the form of hydrogen carbonate ions, formed in

red blood cells and carried in plasma x Some combines with haemoglobin forming carboaminohaemoglobin x 7% is dissolved in plasma

Oxygen x Around 1.5% travels dissolved in plasma x Binds to haemoglobin molecule, via diffusion across the biconcave

red blood cell surface oxyhaemoglobin

Water x In plasma as the basis of the cytoplasm in all cells and the interstitial fluids surrounding cells and blood and lymph system

Salts x Carried in blood as ions dissolved in blood plasma

Lipids x Are insoluble due to their strong hydrophilic end so many are not able to dissolve in plasma. Although small proportions of fatty acids and glycerol are soluble and enter the blood stream directly, most are packaged into droplets, then through lymph system and into bloodstream. called micelles

x Micelles are transported in colloidal solution. Which are then absorbed as they pass into lacteals inside the villi of the small intestine. During this process they form into chylomicrons to which they join the blood stream.

Nitrogenous waste x Includes urea, uric acid, creatinine and ammonia and some non used amino acids are carried dissolved in blood plasma

x Metabolic nitrogenous waste is broken down by liver and removed via kidneys

x Explain the adaptive advantage of haemoglobin

Haemoglobin:

Structure

x Protein made up of 4 polypeptide chains each folded polypeptide chain is called a globin. Towards the centre of each globin is a haem unit (iron containing group). The iron weakly binds with the oxygen to form oxyhaemoglobin

x Each haem is a red pigment molecule and the iron necessary for haemoglobin formation is obtained from the diet.

x Iron is necessary in diet to maintain haemoglobin in red blood cells

Adaptive advantage

x Major role of Hb is to transport oxygen. This is insoluble so cannot be dissolve in plasma, this binds to haemoglobin

x At high altitude, blood cannot absorb amount of oxygen at sea level. Thus body adapts by initially increasing heart rate, breathing rate, then the number of red blood cells --> more haemoglobin

x Is able to increase the oxygen carrying capacity of blood o 4 haem units on haemoglobin molecule allow it to bond with 4 oxygen molecules

x Ability to bind oxygen increases once the first oxygen molecule binds to it o The bonding on each oxygen molecule to the haemoglobin molecule, changes it

shape slightly making the rate and efficiency oxygen uptake increase.

Small increase in oxygen concentration in the lungs can result in a large increase in oxygen saturation in the blood.

x Capacity to release oxygen increase when carbon dioxide is present. o Important to release oxygen to cells that need it, while uptaking oxygen at

respiratory surfaces o Metabolising cells release CO2 which combines with water and forms carbonic acid,

lowering the pH. Haemoglobin reduces the affinity for oxygen at lower pH, release it. Bohr effect

x Compare the structure of arteries, capillaries and veins in relation to their function

Blood Vessel Diagram How structure is related to function Artery Transport oxygenated blood away from heart

Thick, elastic and muscular layer- high pressure of pumped blood Elastic fibres- expand and recoil, controlling blood pressure Smooth muscular fibres- control diameter of artery and rate of flow of blood

Vein

Transport deoxygenated blood towards the heart Thin, elastic and muscular layers, wider diameter- Flows at a much lower pressure Valves ensure that blood flows in one direction Situated between skeletal muscles to help push blood through veins

Capillaries

1 cell layer thick, small diameter of lumen, narrow- red blood cells must pass through single file, slows down flow to allow for exchange of materials Surround body tissues, expansive network, large surface area- efficient exchange

x 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

Organ/ Tissues

Chemical that changes in composition

Why does the change in concentration occur

Lungs - Oxygen increases in blood

- Gas exchange occur - Oxygen diffuse from lungs into blood for

- Carbon dioxide decreases

respiration - Co2 diffuses from blood to be excreted

Small intestine

- Products of digestion increase (glucose, amino acids)

- Diffuse across the villis of small intestine and into blood to be carried to body cells for respiration

Large intestine

- Water, vitamin, mineral concentration increases

- Diffuses across the large intestine walls and into blood to reach cells

Liver - Unwanted substances decrease (toxin, alcohol)

- Urea increases - Minerals decrease - Glucose may

increase or decrease

- Removes and breaks down toxins etc - Removes excess amino acids and ammonia

from blood and converts to urea called DEAMINATION

- Stores some vitamins and minerals - Can remove glucose wen sugar levels are

high - When levels are low- release glucose into

blood from stores of glycogen Kidney - Urea decreases

- Salt and water decrease

- Urea is filtered out of blood and kidneys and excreted

- Remove any excess salt and water by osmoregulation

Brain and active muscle

- Oxygen decreases - Co2 decreases - Glucose decreases

- High rate of respiration occurs which requires glucose and oxygen

- Releasing CO2 in the blood

Substance Source Destination Form/component carried in blood

Oxygen Alveoli in lungs from inhaled air

Heart and tissues of body for respiration

Oxyhaemoglobin in red blood cells Dissolved in plasma

Carbon dioxide Body cells Alveoli in lungs Plasma Water Waste product of

cellular respiration Kidneys Plasma

Salts Capillaries Kidney Plasma Lipids Lymph vessels Nitrogenous waste Liver Kidney Amino acids and glucose

Small intestine Liver

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

Need for Oxygen:

x Is necessary for cellular respiration, a process where cells obtain energy from glucose x This energy is needed for growth, repair of tissues, movement, excretion, reproduction.

However this energy must be converted into form for living cells to use in metabolism x Oxygen combines with glucose via a series of enzyme controlled steps during cellular

respiration to release ATP o This is called oxidation of glucose and it occurs in all living cells

C6H12O6 + 6O2 + 6H2O 6CO2 + 12H2O + ATP

Removal of carbon dioxide

x Produced in cells as a waste product of chemical respiration. It must be removed to prevent a change in pH in the cells, bloodstream and body.

o When CO2 reacts with H2O it forms carbonic acid. A build up of carbonic acid is toxic as it lowers the pH of the cells and blood stream, affecting the homeostatic balance within an organism. CO2 + H2O H2CO3

x A lower pH will prevent the enzymes and cell functioning by reducing the metabolic efficiency. Thus it is essential to be removed for optimal functioning of enzymes.

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

1. CAT Theory (cohesion-adhesion-tension theory) Xylem

What is it: - Movement of water and mineral ions through xylem - Root pressure forces the solution which has been absorbed into the roots into the xylem

upwards - Most upward movement is due to Transpiration stream occurs due to physical forces from

water being moved by passive transport, evaporative suction pull of water is pulled up through stem

Evidence: - Xylem vessels are hollow very little resistance to the flow of water - Properties of water:

o Cohesive forces (attraction of water molecules to each other) o adhesive forces (attraction of water molecules to walls of xylem) lead to capillarity

(water rises up xylem) - Concentration gradient exists across leaf

o Surface of the leaf, the osmotic pressure is high, water concentration is low as it is constantly being evaporated through the stomata

o Centre of the lead, the osmotic pressure is low, water concentration is high

2. The pressure flow theory (source path-sink theory) phloem

What is it?

- Translocation in phloem tissue moves products of photosynthesis by active transport - Mechanism of flow is driven by an osmotic pressure gradient, which is a continuous flow as

sucrose is continually being added to one end and removed at the other- due to difference in sugar and water concentration

What happens: - Active loading of sugar, amino acids, sucrose, other mineral nutrients into phloem (source eg. leaves)- the pressure attracts water to flow in due to differences in osmotic pressure 1. Symplastic loading- sugars move in the cytoplasm from the mesophyll cells 2. Apoplastic loading- sugars move along a pathway through the cell walls, cross cell membrane to enter phloem tube, pass through sieve cell by active transport

- Increases the solute (sugar) concentration - Active unloading of sugar from phloem into surrounding tissues (sink eg. roots or flowers)-

pressure causes water to flow out

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

Longitudinal section Transverse Section Xylem

Phloem

x Perform a firsthand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water

See Prac worksheet in folder

x Perform a firsthand investigation used the light microscope and prepared slides to gather information to estimate the size of red and white blood cells and draw scaled diagrams of each

See Prac worksheet in folder

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

Arterial blood gas analysis

- Takes blood samples from artery and the sample is tested to determine different substances. The test evaluates respiratory diseases and conditions to show how effective the lungs are at removing carbon dioxide and bringing oxygen to the blood. It is an invasion procedure. A limitation is that a sample left at room temp must be analysed within 10-15 min and a sample on ice within an hour.

Current technologies for measurement of oxygen saturation in blood

A Pulse Oximeter is an instrument that measures the amount of oxygenated haemoglobin in the blood.

- The amount of oxygen in the blood determines how much light is absorbed by haemoglobin.

- Non invasion technique, relatively cheap and simple to use, useful screening tool

It uses two wavelengths of light: red (660 nm) and infra red (910 nm). photodetector receives the signals and a processor- measure absorbed to calculate oxygen saturation Oxygenated haemoglobin absorbs more infra red light and allows more red light to pass through.

Uses: Monitoring oxygenation and pulse rates during anaesthesia, during recovery phase and in intensive care during mechanical ventilation Limitations: Readings may not be accurate - if severe hypotension, cold, cardiac failure. Intravenous dyes can also give false readings and they cannot distinguish between carboxyhaemoglobin and methaemoglobin.

Current technologies for measurement of carbon dioxide concentration in blood

- Carbon dioxide is produced as a metabolic waste from respiration toxic to cells - Can travel in the blood via hydrogen carbonate ions, dissolved carbon dioxide or bound to

haemoglobin as carbamino compounds

Capnometers measure the amount of carbon dioxide in expired air.

- It is a safe, non

Use changes in the infra red light transmission properties and consist of an infra red transducer, a pump to draw the gases through a tube, a water trap and a microprocessor.

Uses: They are used during anaesthesia, in lung studies and in intensive care, monitoring the performance of assisted ventilation. Limitations: include the presence of gases in the sample that the device cannot measure, e.g. helium.

invasive test with few hazards

High breathing frequency can also affect the response capabilities of the capnometer.

x Analyse information from secondary sources to identify the products extracted from

donated blood and discuss the uses of each product

Donated Blood Products Uses Discussion

Red Blood cell concentrate Contain about twice as many red blood cells as normal, is

used to boost the oxygen carrying capacity of patients with anaemia or after blood

loss Treats the haemoglobin levels

of patients while not increasing the blood volume for people

suffering anaemia, kidney failure, and traumas.

For: can be used to boost the oxygen carrying capacity of a patient. High level of specificity more efficient when separated into separate components. Against: is a liable product, a perishable blood component with a short shelf life and must be transported under certain refrigerated conditions

x 42 day shelf life x Risk of infection,

allergic reaction Platelet concentrate Is given to patients who need

extra blood clotting capability, such as leukemia sufferers or following severe blood loss

For: can be stable and have long shelf life if it is blood clotting component. Against: is a liable product, a perishable blood component with a short shelf life and must be transported under certain refrigerated conditions

x 5 day shelf life

White blood cell concentrate Given to patients needing a boost to their immune system,

perhaps following a severe infection

For: can help boost the immune system of patient and prevent infections Against: is a liable product, a perishable blood component with a short shelf life and must be transported under certain refrigerated conditions

Plasma Is the liquid part of the blood and is often given in an

For: can be used as a blood volume expander after blood

emergency to boost the volume of blood following severe blood

loss - Contains blood clotting

factors - Adjust the osmotic

pressure - Treat haemophilia

loss, obtain intragram, immunoglobins, anti-D, albumex and prothrombinex Against: is a liable product, a perishable blood component with a short shelf life and must be transported under certain refrigerated conditions

x 12 month shelf life Cryoprecipitate Is a fraction collected from

plasma and contains blood clotting factors. It is used to

treat severe bleeding

For: can be used to treat severe bleeding and contains blood clotting factors Against: is a liable product, a perishable blood component with a short shelf life and must be transported under certain refrigerated conditions

Factor VIII and Monofix Are extracted from plasma and are used to treat people who

have haemophilia (an inherited and incurable disorder in which the blood will not clot properly)

For: is a stable product, thus it has longer shelf life and can be produced fractionally or by recombinant manufacteuring. Used to treat haemophilia and blood clotting

x 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.

Progress in the production of artificial blood

Developments Description Benefits Uses Volume Expanders

- Are fluid solutions that are inert and used to increase the blood volume.

- The blood is dilute and has a lower concentration of red blood cells.

Non oxygen carrying blood substitutes can be crystalloid solutions which contain salts and or sugars, e.g. saline solution. universal acceptance by all blood groups

Emergency situations such as trauma patients These plasma expanders are effective for blood loss and most have few negatives

Perflurocarbon Dr Leland Clark-

- Oxycyte and flurovent, easily dissolve oxygen and carbon dioxide

Carries 50 x more dissolved oxygen than plasma.

Uses include surgery, trauma, and oxygenation of tumours

mid 1960s high demand in Vietnam War

and can transport these gases to tissues and lungs respectively

- They are combined with other materials, e.g. lipids, to form emulsions which can be injected into the patient.

stored at room temperature do not need typing or cross matching Most are inert and chemically stable and can be fully sterilised.

during radiation and chemotherapy.

Haemoglobin based oxygen carriers

- Combine with oxygen. Clinical trials are ongoing as HBOCs are not protected by a cell membrane and hence not protected from degradation

- They are based on haemoglobin from humans, animals and recombinant technology.

Produced in large quantities at a low cost free of infective agents and allergens, making them non toxic and disease free Do not trigger the immune response Have a long shelf life

Limitations: Vasoconstriction and there can be gastrointestinal side effects, e.g. nausea, vomiting.

Reasons why artificial blood research is needed

x Further research needed to enclose the haemoglobin, with the required enzymes, inside an artificial cell membrane a lipid vesicle to increase circulation time.

x Further research is needed to make perflurocarbon emulsions with lipids for effective with large enough quantities to make a significant result as they currently have short circulating life

1. Cheaper to produce - Current estimates of the costs of blood substitues range between 300 and 1000 dollars. The

current cost of a unit of blood varies by region, but the highest current cost is about $200. 2. Safer to use

- Although transfused blood in the US is very safe, with between 10 and 20 deaths per million units, blood substitutes could eventually improve on this.

3. Developing nations - 10-15 million units of blood are transfused each year without testing for HIV or hepatitis.

Blood transfusion is the second largest source of new HIV infections in Nigeria. In certain regions of South Africa as much as 40% of the population has HIV/AIDS, and thorough testing is not financially feasible. A disease-free source of blood substitutes would be incredibly beneficial in these regions. Hemopure is currently approved for use in South Africa, largely because it is a major improvement over the blood supply in this region.

4. Increase in demand - About 14 million units of blood were used last year in the United States alone. According to

Dr. Bernadine Healy, former president of the American Red Cross, donations are increasing by about 2-3% annually in the United States, but demand is climbing by between 6-8% as an aging population requires more operations that often involve blood transfusion. New York City currently relies on Europe for 25% of its blood supply.

- Supply blood quickly and effectively to soldiers and people in critical trauma situations.

5. Replacement for Donated Blood - Blood supply is voluntarily donated and therefore the amount varies, can be critically low at

times of need - Donated blood has a relatively short shelf life, e.g. platelets have a shelf life of 5 days - Donated blood is difficult to transport and needs certain conditions

3. Plants and animals regulate the concentration of gases, water and waste products of metabolism in cells and in interstitial fluid.

x Explain why the concentration of water in cells should be maintained within a narrow range for optimal function

Water is a universal solvent in cells

- Amount and concentration of water must be kept constant - Molecules such as salts, ions and respiratory products can be dissolved and transported

through the water medium - Water can change solute concentration and pH - If too much water the cells can burst or too little the cells can shrink

Maintenance of Osmoregulation - water regulates osmotic pressure

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

Metabolic wastes, particularly nitrogenous wastes, are toxic to cells.

- the by-products of the breakdown of proteins and nucleic acids, are toxic to cells and must therefore be removed quickly

- Nitrogenous wastes have the ability to change the pH of cells and interfere with membrane transport functions and may denature enzymes.

o Nitrogenous waste such as ammonia can cause an increase in pH of cells, resulting in them becoming more alkaline

o Carbon dioxide accumulation which lowers the pH, results from internal environment becoming too acidic.

- Increased solute concentrations interfere with reaction rates and an osmotic imbalance adversely affects membrane functioning

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

Kidney:

The excretory system is a group of organs that function together to remove metabolic wastes from the tissues of an organism and expel them to the outside.

Mammals: Filtering the blood and removing nitrogenous wastes from the body in the form of urine

- Plays a central role in homeostasis, forming and excreting urine while regulating water and salt concentrations in the blood. It maintains the precise balance between waste disposal and the animals need for water and salts

Fish : - dependant on the environment of the fish. Produce urine that ensures homeostasis is maintained in the body by osmoregulation

- In marine (salt water) environments, the kidneys excrete small quantities of isotonic (same concentration as sea water) urine. This helps conserve water and excrete the excess salt they gain from their hyperosmotic environment.

- In freshwater fish, the kidneys work continuously to excrete copious quantities of dilute urine, which also has a very low salt concentration. This helps to remove excess water gained from the hypo-osmotic environment.

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

Diffusion and osmosis are both types of passive transport that require no energy input and are relatively slow. They rely on random movements of molecules. Diffusion is too slow for the normal functioning of the body and does not select for 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.

Problems with Diffusion Problems with Osmosis - The rate of movement is too slow

o Nitrogenous waste must be dissolved in water to be removed. Thus wastes would only be able to move if they were more concentrated inside the cells or the bloodstream rather than the fluid outside.

- Not all wastes can be removed via diffusion o If concentrations within the blood and

urine equalised and no further wastes

- Too much water may be lost in urine

o Urine contains large number of nitrogenous wastes in solution, water must be drawn into the urine by osmosis to dilute the wastes and try to equalise the

were removed, their accumulation would change the pH of cells and become toxic.

- Active transport is therefore essential to remove wastes such as uric acid against the concentration gradient from blood into urine in the kidneys.

concentrations of the fluid inside the urine and in the surrounding kidney.

- Movement of water may make wastes too dilute for excretion by diffusion.

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

- Within the kidney, the movement of substances between the bloodstream and excretory fluid in the microscopic tubules (nephrons) involves both active and passive transport

Transport Details Mammalian Kidney Passive - Process of

diffusion and osmosis

- No energy input - Along a

concentration gradient

- Passive transport moves water and some nitrogenous wastes such as urea and ammonia in the kidney of mammals

- Filtration - 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.

Active - Involves a carrier

protein - Energy input - Selective process - Can move against

a concentration gradient

- Reabsorption, Secretion - Moves mainly sodium ions, glucose, amino

acids and hydrogen ions across the wall of the nephron

- 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

- Sodium salts reabsorbed, glucose and amino acids reabsorbed, removal of nitrogenous waste

x Explain how the processes of filtration and reabsorption in the mammalian nephron

regulate body fluid composition

Filtration

- occurs in glomerulus filtrate in the Bowman's capsule where high blood pressure in the glomerulus forces all small molecules out of the blood into the capsule

- Water, urea, ions (Na+, K+, Cl- , Ca2+, HCO3- ), glucose, amino acids and vitamins are all small enough to be moved into the glomerular filtrate. 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.

- Filtration of blood takes place at the surface between the glomerulus and the inner lining of each Bowmans capsule.

- Substances within the blood that are small enough to go through the capillary wall under pressure pass through the cellular layer lining the bowmans capsule and move into the lumen. Blood cells and proteins are retained n the blood, while large volumes of water pass through, carrying dissolved substances such as amino acids, glucose, salts and nitrogenous wastes glomerular filtrate

- Separates from blood depending on size - Is the movement of materials across the filtration membrane into the lumen of Bowmans

capsule to form filtrate

Reabsorption:

- Reabsorption takes place selectively at various points along the proximal tubule, loop of Henle and distal tubule. All glucose molecules, amino acids and most vitamins are recovered, although the kidneys do not regulate their concentrations. The reabsorption of the ions Na+, K+, Cl- , Ca2+ and HCO3-occurs at different rates depending on feedback from the body. In some cases, active transport is required. Water is reabsorbed by osmosis in all parts of the tubule except the ascending loop of Henle. The amount of water reabsorbed depends on feedback from the hypothalamus. If no water were reabsorbed human would soon dehydrate, losing water at a rate of around 7.5 L per hour. The chemical composition of the body fluids is precisely regulated by the control of solute reabsorption from the glomerular filtrate.

Secretion (active) collecting duct, PCT, DCT

x Outline the role of the hormones aldosterone and ADH in the regulation of water and salt levels in the body

Hormones are chemical control substances that are secreted by endocrine glands, directly into the bloodstream.

Aldosterone brings about the retention of salts within the body

ADH (anti-diuretic hormone) brings about water reabsorption within the body.

- Produced in the adrenal gland - A decrease in the concentration of

potassium/ sodium ions - Aldosterone increases the permeability

of the nephron to sodium, particularly in the ascending limb of the loop of Henle

- Reabsorption of sodium ions from the nephron into the surrounding kidney tissue and capillaries occurs, resulting in the retention of salts by the body

- Increase in chloride ions/ water - Increase in blood pressure and blood

volume - Fludrocortisone?

- Hypothalamus detects Dehydration - leads to blood volume dropping

- It stimulates the posterior pituitary gland to release the hormone ADH which acts on the nephrons of the kidneys to increase the reabsorption of water

- The presence of ADH increases the permeability of the membranes of the cells lining the distal tubules and collecting tubules to water thus water is reabsorbed into the kidney tissue and bloodstream

- Decrease urine volume, increase urine concentration, increase blood volume

ADH and aldosterone play an important role in helping the kidney carry its homeostatic functions of osmoregulation

- Regulation of salt concentrations of the blood

- Regulate blood volume

x 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 function in response to variation in the environment

- Applicable to any organism (plant or animal) that live an environment that varies - E.g. estuary in its salt concentration varies to carry out enantiostasis to maintain

homeostasis

Estuaries

- Estuarine organisms are eurynaline (tolerant salinities) - High tide environment brings high salt concentration (high osmotic pressure) - Low tide, sea water flows out and fresh water flows to estuary - Periodic tidal fluctuating conditions

Osmoconformers Osmoregulators Organisms that tolerate the changes in the environment by altering the concentration of their internal solutes to match the external environment

Organisms that avoid changes in their internal environment and have the ability to keep the solutes at an optimal level

Use small organic molecules to vary the solute concentration in their cells to match that of the surroundings

Their body fluids are similar to those in a marine environment, so when exposed to fresh water, the water tends to accumulate by osmosis. To counteract this, the animal produces more dilute urine, to reduce the internal water concentration to a level at which the cells can function

The osmotic pressure inside the body and outside are the same

A higher osmotic pressure is maintained inside the body than in the external environment

Examples: - Fiddler crab - Sharks

Examples: - Mussels - Salmon - Polychaete worms

Organisms that tolerate changes by altering the concentration of their internal solutes to match external environment Metabolism able to tolerate changes in salinity

Use active transport to maintain a constant osmolarity of blood and intersitiual fluid regardless of changes in surrounding water

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

Minimising Water Loss in Plants: (note: main form of water loss is transpiration)

Mechanisms that minimise Features/adaptations Water conservation and

water loss examples Reducing the internal temperature of plants

- Shiny, reflective waxy leaves

- Thick, insulating cuticle

- Allows the plants to use less water for evaporative cooling

- Waterproof epidermal cells prevent water loss

e.g. waxy leaves on salt bush course/leathery leaves of eucalypts

Reducing the exposure of leaves (stomata) to the sun

- Leaf orientation in eucalypts

- Leaves reduced to leaflets

- Leaves reduced to scales

- Rolled leaves

- Cladodes are think and have regular intervals to conserve water

- Phyllodes

Reducing the difference in water concentration between the plant and the outside air

- Sunken stomata - Hair on leaves - Rolled leaves

- Sunken stomata in the hakea and in the cladodes of she oaks

Features related to water storage

- Succulent plant organs - Woody fruits

- Calandrinia, fleshy stems or leaves which are able to swell up and retain moisture

x Analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney

Renal Dialysis

Wastes in the blood are removed by diffusion across a partially permeable membrane. Limitations- time consuming; only lmited amounts of wastes can be removed from the blood, sodium phosphate and potassium ions are not excreted

Types of Renal Dialysis

Similarities Differences

Haemodialysis - A partially permeable membrane filters the blood, allowing wastes to pass through but not blood components

- A dialysis solution is used

- Diffusion of blood occurs into the dialysis solution

- Blood is passed into a dialysis solution outside the body

- Blood moves through plastic tubing - Can be used only 3 times a week for

4 hours at a time - Anti-clotting agent, heparin is

added - Requires a constant temperature

bath Peritoneal Dialysis - Undertaken inside the body in the

- Dialysis solution has similar ion components to blood

peritoneal caviety - A catheter is used - Can be taken daily, 4 times a day for

4 hours

Kidney function vs Renal Dialysis

Similarities Differences Renal Dialysis

- Remove wastes in the form of urea

- Movement of dissolved substances through semipermeable membrane

- Both involve passive transport

- Movement across membrane through diffusion - Removal of wastes (urea) only - An external body process - Perfmoed by a dialysis machine attached to a computer - Periodically- 3x a week - Concentration is monitored by machines so wastes are

removed - Inconvenient, time consuming, less effective, some side

effects Kidney - Movement across membrane is active transport,

osmosis, diffusion - Filters and reabsorbs substance and secretes - An internal body process - Performed by two fist sized organs - Removes waste constantly - Varies concentration of ions automatically, depending

on the bodies needs - No side effects - Wastes may be removed by both active and passive

transport

x Outline the general use of hormone replacement therapy in people who cannot secrete aldosterone

Aldosterone increases the amount of salt reabsorbed from kidney tubules and as a result it also helps regulate blood pressure, blood volume

Lack of Aldosterone Consequences Hormone Replacement Therapy

Consequences

Addisons Disease- caused by

- Damage to the adrenal gland that produces aldosterone

- Damage to the pituitary gland that controls the adrenal gland

Results in low sodium levels and high potassium levels in blood Severe cases of mineral ion imbalance, blood pressure drops due to the low amounts of sodium and potassium ions an imbalance of hydrogen ions lead to lowering

Restoring the imbalance of the hormones at levels that are normal for the body modern day hormone replacement therapy involves administering a genetically engineered hormone called fludrocortisone.

can increase fluid retention raise blood pressure remove the danger of heat failure

of blood pH and blood glucose imbalance may arise

x Compare and explain the differences in urine concentration of terrestrial mammals, marine fish and freshwater fish

Organism Excretory Product and Concentration

Environmental Reason

Terrestrial Mammals

Varied concentration of urine (mammals in desert, highly concentrated) (herbivores, less concentrated) URIC- UREA

FACE THE DIFFICULTITY WITH CONSERVING WATER AND REMOVING NITROGENOUS WASTES AT SAME TIME

- body needs to conserve water- (hot days) excrete concentrated urine so that water is conserved

- (Cool days)- dilute urine is excreted by kidneys - Water content of blood & blood pH is maintained at a

constant level- kidneys able to adjust the concentration of water and salts in urine

- Varies in terms of concentration of water and dissolved substances

- Humans: urine is 4.2 more concentrated than blood plasma

- Kangaroo rats:diet contain almost no water, urine is highly concentrated

Marine Fish Eg. native bass

Set High Concentration of Urine Urea- to avoid dehydration

PROBLEM OF OSMOSMIS- Water moves out - Water surrounded fish has higher concentration of

solutes (more salts) - Water moves out of fish by osmosis along concentration

gradient - Needs to conserve water, small quantities of

concentrated urine are excreted.

Freshwater Fish Eg. whiting

Set Dilute Concentration of urine (urine has a lot of water relative to the solutes) Ammonia- highly toxic, remove quickly

PROBLEM OF OSMOSIS- Water moves in - Water surrounded fish has low concentration of solutes - Water moves by osmosis along concentration gradient - More water moves from environment into body tissues-

balance the amount of water - Large Quantities of Dilute urine are excreted

x 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

Organism Type of nitrogenous waste excreted- toxicity, amount of energy needed

Relationship between conservation of water and excretion of nitrogenous wastes

Insects Eg. blow fly

Uric acid low toxicity Low energy (

x Discuss processes used by different plants for salt regulation in saline environments

x Perform a firsthand investigation to gather information about structures in plants that

assist in conservation of water

Characteristic How it reduces water loss Plant example Banksia Serrata

- Thick cuticle on leaves

- Woody fruits - Serated edge of leaf

reduces SA

- Reduced surface area

- Limits water loss via evaporation

- Waxy thick leaves, thus no water leaves

- Reduced evaportation

Organism Processes for salt regulation Grey Mangrove

- Secretion: Special salt gland in its leaves that excrete salt - small leaves hanging vertically to reduce the surface presented to the

sun and thus reducing transpiration - far-reaching, exposed roots- pneumatophores that build off from the

roots to the surface to get oxygen - restrict opening and closing of stomata - Salt desposits: deposit salt on older tissue (bark and leaves) which are

then discarded and excreted by shedding - Able to metabolic function, by minimising salt concentration and toxicity

and increasing water content in large vacuole Salt Bush (Salt tolerant)

- Salt barriers- special tissues in the roots and lower stems stop salt from entering the plant but allow uptake of water

- accumulates salt in the swollen leaf bases which fall off, thus removing excess salt and Sporobolus virginicus has salt glands on its leaves.

- Minimal salt content through structural and physiological adaptations

She oak - Sunken stomata - Reduced surface

area - Small leaves with

crown shape scales - Drooping orientation

- Reduced surface area and orientation

- Limit evaporation and direct sun contact

Eucalypts

- Orientation drooping - Stomatas open in

cool parts and closed at hot times

- Waxy thick cuticle

- Waxy cuticle prevents loss of water

- Orientation prevents sun exposure directly limiting evaporation

x Perform a firsthand investigation of the structure of a mammalian kidney by dissection, using a model or visual resource and identify the regions involved in the excretion of waste products

Blueprint of life 1. Evidence of evolution suggests that the mechanisms of inheritance,

accompanied by selection, allow change over many generations Evolution: is the development and progression of life forms and organisms overtime

x Outline the impact on the evolution of plants and animals of: o Changes in physical condition o Changes in chemical condition o Competition for resources

Changes in: Impact of Evolution on Plants and Animals Examples Physical Condition

Change in Australian climate from cool and wet hot and dry

- affect vegetation from rainforest to woodland, dry sclerophyll forests

- Drying up of lakes - Influence of fire - Dust clouds - Fire resistant

Snow gums have developed adaptations to conserve water

Chemical Condition

Changes in pH, salinity, presence of minerals - Anoxic to oxic environment has led to

DDT antibiotic resistant bacteria Peppered Moth

simple to more complex organisms Mangroves for salt secretion Competition for Resources

- biotic (living) and abiotic (non living) - Factors: food, water, shelter, pred-prey

relationships - resources have become limited (dry

climate) and thus competition

Fly catchers feed on same insects so competition exists within the species- they now have different behavioural traits to catch prey

Macroevolution takes place over millions of years and a new species arises. There is a correlation between chemical change and the type of organism. E.g. red wolf, jackel, dog

Microevolution is a shorter period and involves changes within a population, e.g. peppered moth

x Describe, using examples, how the theory of evolution is supported by the following areas of study

o Palaeontology o Biogeography o Comparative embryology o Comparative anatomy o Biochemistry

Evidence Supported Theory of Evolution Palaeontology The study of fossils- mostly found in sedimentary rock.

Provides a timeline of evolution in which they exist due to rock layers, suggest evolutionary pathways Transitional Fossils Archaeopteryx

- Reveal a gradual change in life forms over millions of years - Qualities of both reptiles (teeth, tail, reptile-like skeletion) - And Bird (feathers, wishbone, flight muscles)

Biogeography Darwin and Wallace studied the distribution of species in different biogeographic regions

- Using the theories of Divergent and Convergent Evolution- the evidence suggest species have come from Common Ancestors, but have been separated and new species have evolved in order to survive

in their new environmental pressures

Example: Flightless bird (emus/ kiwis) Comparative Embryology

Comparison of developmental stages of species in the embryonic life form.

- Obvious similarities between fish, amphibians, reptiles, birds, mammals - Gill Slits

- Suggesting a common ancestor

Comparative Anatomy

Comparison of anatomical structures on different organisms that have the same basic plan but perform different functions are called homologous structures

- Pentadactyl Limb- monkey, bird, pig, horse, cat basic plan consists of one bone in the upper limb, two in the lower limb leading to five fingers/ toes

- Suggest a common ancestor existed

Biochemistry Comparison of organisms on a molecular basis- study of macromolecular structure of cells in different organism

- DNA sequencing- ordering bases and reveals how closely related organisms are eg. humans and monkey common ancestor

- Amino acid sequencing- humans share 8 amino acids sequences with monkeys and 125 with lampreys (more closely related than expected)

x Explain how Darwin Wallace theory of evolution by natural selection and isolation accounts for divergent and convergent evolution

Darwin Wallace theory of evolution by natural selection assumes that living things arose from a common ancestor and that some populations move into new habitats where they adapt over time to their environments.

1. Variation exists 2. Favourable Characteristic 3. Survive and Reproduce 4. More Common

Divergent Evolution Convergent Evolution When species are isolated changing environmental pressures cause different natural selection process to occur. Specification (new) species arise by splitting or budding

If species exist in similar environment, exposed to similar selective pressures but yet distantly related natural selection could account for their structure similarities.

Example: Darwins Finches in Galapagos islands Kangaroo in Aus Elephants are large plains-dwelling animals that are closely related to a small guinea pig-like animal called a hyrax

Example: Shark, dolphin, penguin (fish, mammal, bird)- streamlined body shape, fins

x Analyse information from secondary sources to prepare a case study to show how an

environmental change can lead to changes in species

Species Peppered Moth (biston betualaria) Physical Change Industrial Revolution- Pollution Change in environment woodlands near industrial cities had a blackened soot on tree trunks.

The light coloured moths were captured and killed by predators more frequently because they could be easily seen resting on the dark tree trunks

Form of Evolution Micro evolution as it took place over a short period of tile and resulted in a change within populations of species but it did not produce a new species

Darwins Theory of Evolution

In the moth population there would have been variation, some black and some lighter. Due to the selective pressures caused by the industrial revolution, the black moths had the selective advantage to camouflage and the white moths more likely to be killed by predators due to conspicuous colour. The black moths became more abundant having the favourable characteristic they can survive and reproduce. Passing on this characteristic to the offspring, the black have become more common in the population.

x Analyse using an example, how advances in technology have changed scientific thinking about evolutionary relationships

Identify technology Advances in technology Then Now

DNA sequencing and hybridisation Amino Acid sequencing

- Early classification of evolutionary relatedness was based on structural anatomy

- E.g. 1860 Ernst Haekl reviewed the hind limb walking and enamel on teeth of chimps and gorillas were closer than human and orangotang

- 1960s and 70s Amino acid sequencing of cytochrome C and haemoglobin revealed identical sequence in chimps and humans and 1 difference with gorilla

- DNA compared genes as well as mitochondrial DNA confirming amino acid sequence

- African apes were closer to humans as orangotang had earlier divergence

- Human and chimp 1.6 -3/4 % difference

- Quantitative results

minimise bias Direction of change in scientific thinking about evolutionary relationships

Data from advanced molecular technology such as amino acid sequencing and DNA hybridisation and sequencing has established new links and evolutionary relationships in particular with humans and homo sapiens race. They have created a new phytogenic tree Reveal more closely related organisms

Evaluation Advances in technology have led to a better, more specific scientific understanding of evolutionary relationships and relatedness

x Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments

Historical Development of theories of evolution

Biologist and dates

Theory Evidence of theory

Evidence against theory

Social and Political influences

Acceptance of Theory

Jean Baptiste Lemarck 1790 research 1802-22

Inheritance of acquired characteristics Animals from simple to complex Adaptation of animals to environment

Observations e.g. giraffes

Characteristics cannot be inherited

Enlightenment questioning creationism and species creation Industrial revolution Scientific growth and knowledge

Not accepted although adapted

Charles Darwin 1830+

Theory of evolution via natural selection and isolation

- Gradual

Galapagos observation e.g. finches

Challenged by punctuated equilibrium against gradualism

Science was socially accepted but not fully understood Uproar of theologians

Accepted today

Alfred Wallace 1848 - 62

Theory of evolution via natural selection and isolation

- Gradual

Biochemistry and observations of Indonesian birds

Challenged by punctuated equilibrium against gradualism

Science was socially accepted but not fully understood Uproar of theologians

Similar and accredited alongside Darwin

Gould and Eldridge 1970s

Theory of punctuated equilibrium

Many fossilised remains

Modern industrial power and

Debated although accepted in

- Short bursts of evolution

showed no noticeable evolutionary change e.g. soft bodied sea organisms

knowledge of science

some circumstances

x Perform a firsthand investigation to model natural selection 1. Collect 50 green and 50 yellow pick up sticks 2. Scatter randomly over green grass 3. For 2 mins time how many sticks one person (predator) can collect in that time 4. Repeat steps 2-3 again, leaving the unpicked up sticks and not the eaten (prey)

Results: the yellow sticks were found to be ill-suited to the environment and were eaten more than the green which were conspicuous

x Perform a firsthand investigation to gather information to observe, analyse and compare the structure of a range of vertebrates forelimbs

Observe the pentadactyl limb which is used for varying functions

Cat Human Frog Bird - Long humerus - Long radius - Short falangies

- Long humerus - Long radius - Long fingers

- Long humerus - Short radius - Long carpels

- Short humerus - Long radius - Varying fingers

2. Gregor Mendels experiments helped advance out knowledge of inheritance of characteristics

x Outline the experiments carried out by Mendel

Gregor Mendel (1822 84) the father of genetics

Experiment peaplants 1860s to investigate their breeding patterns to determine the inheritance of characteristics

Why / Features - Easy to grow - Produced new generations quickly - Easily distinguishable characteristics - Strictly control the breeding patterns - Used pure breeding lines - Self-pollinating the flowers to make sure pollen from the stamens

lands on the carpel of the same flower - Cross-fertilisation was ensured by cutting off stamens from a flower

before pollen was produced, then dusting the carpel of the flower with pollen from another plant

- To ensure reliability, Mendel used thousands of plants in each experiment.

Characteristics seven characteristics found in peas:

o Flower colour, purple or white o Flower position, axial or terminal o Seed colour, yellow or green o Seed shape, round or wrinkled o Pod shape, inflated or constricted o Pod colour, green or yellow o Stem height, tall or short

Laws Mendels law of dominance and segregation

Mendels law of independent assortment Results Each of the seven traits that Mendel studied had a dominant and a

recessive factor. When two true-breeding plants were crossed, only the dominant factor appeared in the first generation. The recessive factor appeared in the second generation in a 3:1 (dominant : recessive) relationship.

Mendels Experimental

technique Summary of Mendels Work and his results Significance of

Mendels results and his explanation

1. To establish pure breeding lines

What he did: Established

Pure-breeding line 1 Tall x tall all tall offspring = pure bred tall Pure breeding line 2

Result: the offspring of pure breeding lines all resembled their parents, ensuring that they in turn are pure

two pure breeding lines one tall one short How he did it: male and females enclosed within the same flower

Short x short all short offspring = pure bred short

breeding for a particular trait Importance: The resulting tall and short offspring that are pure bred lines become the P of parent generation in subsequent crosses

2. To create hybrids by crossing individuals with contrasting pure bred characteristics

What he did: cross bred two plants with contrasting pure bred characteristics tall x short How he did it: manually transferred pollen between tall and short plants

Create hybrid offspring:

Results: when parents that are pure breeding for contrasting characteristics are crossed, the offspring all resemble one parent Explanation: these offspring (F1) are termed hybrids, but they resemble only one parent the dominant characteristic and the recessive characteristic.

3. To carry out a monohybrid cross

What he did: Crossed two hybrid plants from the first filial generation of the previous experiment, identified the resulting offspring as tall or short and counted offspring How he did it: some were allowed to undergo self pollination, whereas others were cross pollinated, because all were hybrids; large sample size

Result: when two hybrid plants are crossed, one dominant characteristic appears 3 x as frequently in the offspring as the other recessive. 3: 1 ratio.

4. Conclusions Mendel derived principles based on mathematical calculations. He showed that these ratios arise if an individual possesses two factors for any characteristic, where one is dominant over the other and these two factors segregate or separate when they are passed from parent to offspring Explanation: Mendel proposed that during reproduction, the two factors segregate and each passes into a separate gamete. When two gametes combine during fertilisation, each contributes one factor to the new formed offspring

- Mendel used statistics to calculate the probability of different combinations of factors pairing in offspring and he obtained a 3:1 ratio

5. Assessing the validity of conclusions Collated data: Mendel made direct counts of the resulting offspring, giving quantitative data which he collated and analysed identifying patterns and trends Conclusions: Mendel applied logical thinking and mathematical model to the data he had gathered, leading to valid conclusions.

x Describe the aspects of the environmental techniques used by Mendel that led to his success

He drew valid conclusions which became known as Mendels laws:

- Studied separate characteristics one at a time- easily observable - Used pure breeding lines by self-pollination - Used quantitative results (3:1 ratio) - Large number of plants to increase accuracy - Cross-pollinated by hand - Studied traits that had two easily identified factors

Valid and reliable used large sample size and repeated his experiments for different traits

Accuracy reduced experimental error as all experiments were conducted in a controlled environment and those crosses that relied on self fertilisation were conducted by keeping the plants isolated from any other, ensuring no accidental cross pollination, removing the stigma and anther of others and then manually transferring pollen from the anthers of one plant to the stigma of another, preventing accidental self pollination

x Describe the outcome of monohybrid crosses involving simple dominance using mendels explanations

Monohybrid: is an individual that has contrasting factors for one characteristic

- Monohybrid inheritance is therefore the inheritance of a single pair of contrasting characteristics

Mendels Law of dominance and segregation

- Only one member of a pair of factors can be represented in any gamete (segregation) - When two hybrids breed statistically they produce a ratio of three offspring showing the

dominant trait to one recessive offspring. He called these traits factors but today they are called genes. Contrasting forms of the same gene are alleles.

Mendels Laws

- Each characteristic or trait in an individual is controlled by a pair of inherited factors - Mendels factors pass as unmodified units to successive generations according to set ratios - Individuals have two factors for each characteristic and they may have two factors the same

(pure breeding) or two factors that differ (hybrid breeding) - The trait that is expressed in the hybrid individual is dominant (Mendels first law of

dominance) - During gamete formation, the pair of factors for a trait segregate (Mendels first law of

segregations) - When the inheritance of more than one trait is studied, the pair of factors fro each trait

separate independently from the other traits of factors (Mendels second law independent assortment)

A monohybrid cross involving simple dominance Outcomes of monohybrid crosses using Mendels explanation

Monohybrid offspring are created when pure breeding parents with contrasting characteristics are crossed All gametes from pure bred tall will contain the factor T similarly gametes from pure bred short will contain t Each hybrid F1 individual inherits one factor from each parent (Tt) The monohybrid plants of the first filial generation all resemble the parent possessing the dominant characteristic. The factor that is expressed is dominant in preference to the other factor (recessive), which is hidden When the hybrid plants produce gametes, the factors for tallness and shortness segregate or separate, with

the result that one half of the gametes contain the factor for tallness (T) and the other for shortness (t) During fertilisation the gametes fuse, each contributing one factor to the resulting F2 offspring In the plants of the 2nd filial generation, the dominant characteristic appears 3 x more frequently than recessive one. As a result a monohybrid cross there is a 3:1 dominant to recessive.

x Distinguish between homogenous and heterogeneous genotypes in monohybrid crosses

Homozygous Individual with the same two factors from individual pure breeding

TT or tt Heterozygous Individual with different factors and from hybrid parents (dominant factor evident

in phenotype) Tt

x Distinguish between the terms allele and gene, using examples

Gene Specific segment of DNA which codes for a polypeptide - specifies a particular characteristic, has two alleles in an individual and two or

more alternative alleles in a population Eg. height in pea plants

Allele Alternative form of a gene - occur in pairs in a diploid individual, segregate during gamete formation, occur

individually in each haploid gamete, pair during fertilisation, when the diploid condition of an organism is restored during zygote formation

Eg. tall or short allele

x Explain the relationship between dominant and recessive alleles and phenotype using examples

Phenotype: is the outward appearance of an organism. The genotype is the actual alleles that are present on the chromosomes of the organism.

A homozygous tall plant would have two identical alleles for height (TT) and would appear tall.

A homozygous tall plant would have two identical alleles for height (TT) and would appear tall.

A hybrid species- phenotype is dominant

Relationship: In this case, tall is dominant and short is recessive and is not expressed. The following diagram shows the results of crossing two heterozygous plants.

x Outline the reasons why the importance of Mendels work was not recognised until

sometime after it was published

Mendel began his work in 1858 and published the results of his experiments in 1866, but his work lay undiscovered until 1900 when others performed similar experiments. It was only then that the importance of his work was realized. It is unclear why such original work went unnoticed, perhaps:

o Mendel was not a recognized, high profile member of the scientific community o he presented his paper to only a few people at an insignificant, local, scientific

journal o accepted theory was that characteristics were blended in offspring- Darwins origins

of species, not that one factor came from each o Other scientists did not understand the work or its significance. o His work was too progressive, radical and was based on very little background sound

knowledge o His work differed radically from previous research and the scientists may not have

understood it

x perform an investigation to construct pedigrees or family trees, trace the inheritance of a selected characteristic and discuss their current use

Pedigrees: are used to show all the individuals within a family and can reveal certain traits genetic disorders. Show the transmission of a character across several generations where the number of individual organisms in each generation is small.

Use: zoos can prevent diease

The pattern of inheritance of a trait in a pedigree may indicate whether the trait concerned is dominant or recessive.

Pattern of Inheritance Key features Autosomal dominant Gene loci on chromosomes other than sex chromosomes

Either sex can be affected Affected individuals must carry at least one dominant allele Unaffected parents will not produce affected offspring

- woolly hair in humans Autosomal Recessive Gene loci on chromosomes other than sex chromosomes

Either sex can be affected Affected individuals must be homozygous recessive Offspring will be affected Two Unaffected parents can produce affected offspring

- albino pigment in hair, skin and eyes X linked dominant Does not skip a generation

Affected males transmit the trait to their daughters and non of their sons

- rare form of rickets is inherited on X chromosome X linked recessive More common in males than females

Affected females pass the trait to all their sons. Affected sons may be produced by normal parents

- haemophilia

x Solve problems involving monohybrid crosses using punnet squares

and other techniques

- A monohybrid cross involves the inheritance of one characteristic. All problems apply Mendel's basic laws of inheritance. The following is typical of a problem that uses Punnett squares to solve problems involving monohybrid crosses.

- Worked example - In peas, the gene for the characteristic tall (T) is dominant over the gene for a short plant (t).

If a homozygous tall plant (TT) is crossed with a heterozygous tall plant (Tt), what will be the possible phenotypes of the offspring?

- A Punnett square is a diagrammatic method of indicating the possible offspring produced from a particular cross.

- - In the sample problem, a homozygous tall plant (TT) is crossed with a heterozygous tall plant

(Tt), By filling in the squares, it is possible to work out all of the combinations that are likely to occur.

- - When you analyse the information in this case, you can predict that 100% of the offspring

will be tall plants: 50% are homozygous tall (TT); 50% will be heterozygous tall plants (Tt).

x Describe an example of hybridisation within a species and explain the purpose of this hybridisation

Hybridisation within a species- the crossing of different variations of one species to produce new varieties of offspring with desirable characteristics

Example:

Hybrid Bob = indian wheat and Canadian fife Inherited Features

- Indian wheat was drought tolerant and resistant to some diseases - Canadian fife wheat matured late and had the best milling and baking

qualities

1870 William Farrer became aware that wheat growing in Australia was presenting problems as strains being grown were not suited to the harsh, dry environment and were susceptible to diseases such as rust and the grain quality was not of a high enough standard for milling and baking

3.Chromosomal structure provides the key to inheritance

x Outline the roles of Sutton and Boveri in identifying the importance of chromosomes

Boveri (1896 1904)

- Worked on sea urchins 1. Nucleus of eff and perm contributed 50% of the chromosomes of zygote

a. Connecting chromosomes to heredity 2. Chromosomes were not all the same and full complement was require for normal

development 3. More hereditary factors than chromosomes recognising that there was more genes on

one chromosome 4. Complete set of chromosomes was needed for normal development

Sutton (1877 1916)

- Worked independently of Boveri on grasshoppers 1. Chromosomes occur in pairs visible in meiosis. One is maternal and the other is paternal

2. During meiosis, chromosomes number is halved as each pair of chromosomes separate (mendels law) and each gamete receives 1 chromosome and fertilisation restores the full number. He stated that chromosomes arrange themselves independently along the middle of the cells before it divides.

3. Connection between behaviours and chromosomes and Mendels work on the inheritance of factors and carriers of hereditary units

4. Chromosomes assort independently during segregation 5. He also believed that several factors were on one chromosome.

Developed the Chromosomal Theory of Inheritance- chromosomes cary the units of inheritance (genes) and occur in distinct pairs

Before Sutton- Boveri After Sutton Boveri Where in the cell are heredity factors found?

Cytoplasm and nucleus Nucleus only

What material stores the heredity information?

? A full set of paired chromosomes, where many heredity factors are carried on each chromosome

How are inherited factors passed to the next generation?

Gametes transport factors but how or what these factors were was unknown

Random assortment during meiosis units of inheritance carried on chromosomes in gametes

Nature of chromosomes Chromosomes were believed to disappear and reappear and were all veiled to be the same size and shape

Chromosomes occur in set numbers in every cell in pairs and each pair of chromosomes has the same size and shape

x Describe the chemical nature of chromosomes and genes - The chemical nature and chemical structure of chromosomes and genes remained unsolved

until the 1940s. - 1953, discovery that DNA is the molecule that meets all the requirements of the hereditary

material

Structure Chemical Nature Chromosomes - Chromosome is a compact coils of thread like molecule DNA,

organised around proteins called histones. - Made up of DNA, long, thin thread like macro molecule, which is

the information carrying part of the chromosome - Proteins around which the DNA is coiled, to keep it neatly

packaged - Chromosomes consist of 40% DNA and 60% protein (histone).

Short lengths of DNA make up genes so genes have the same chemical composition as DNA.

Genes - portions of DNA with a specific sequence of bases that code for

a particular trait.

- genes have the same chemical composition as DNA - A locus is the position of a gene on a chromosome - The total amount of genetic material that an organism has in

each of its cells is called its genome

x Identify that DNA is a double stranded molecule twisting into a helix molecule with each

strand comprising of a sugar phosphate backbone and attached bases adenine, thymine, cytosine, guanine, connected to a complementary strand by paring the bases, A-T and C-G

DNA

DNA structure

- double helix shape two strains of nucleotides

- Each strand of the helix consists of 4 different nucleotides made up of deoxyribose sugar, a phosphate molecule and a nitrogen base.

- sides of the ladder- deoxyribose sugar and phosphate molecules.

- The complementary bases, A-T,C-G, form the rungs (Adenine pairs with thymine and guanine pairs with cytosine)

DNA chemical structure

- Strain is sequence of many nucleotides held together by weak hydrogen bonds in the centre. The strands have a antiparallel arrangement

- The vertical sides are made up of alternating sugar and phosphate molecules

x Explain the relationship between the structure and behaviour of chromosomes during

meiosis and the inheritance of genes

Chromosomes during Meiosis:

- Chromosomes are made of DNA. Genes are coded within the DNA on the chromosomes.

x Explain the role of gametes formation and sexual reproduction in variability of offspring

Discoveries have shown:

- Genes on chromosomes determine characteristics that are inherited - Alleles are different forms of the same gene and occur in pairs in individuals

1. Homologous pairs form 2. Duplicate to form chromatids- each

chromosome (genes duplicate) makes a complete copy of itself, attached at the centromere

3. Crossing Over occurs during metaphase variation (increased number of combinations of genes variation)

4. Independent Assortment- the homologous chromosomes randomly line up in matching pairs at the equator

5. Random Segregation of chromosomes, moving into new cells

6. Next the duplicated chromosomes separate to single strands resulting in four sex cells that are haploid, (ie contain half the chromosome number of the original cell).

During Meiosis 2 1. Two daughter cells that result from

meiosis 1 each undergo meiosis 2 and the behaviour of chromosomes does not affect genetic variation.

Hence: - One cell undergoes two meiotic

divisions to generate 4 haploid cells

- The genes in each haloid cell are a new combo of the paternal genes

The new combo results from crossing over and random segregation, allowing the individual alleles of maternally and paternally derived chromosomes to assort independently

- Haploid gametes carry one copy of each allele from parents to offspring, resulting in genetic recombination and resting the diploid number

- Genetic variation in individuals arises as a result of sexual reproduction. This involves gamete formation (by meiosis), followed by fertilisation

Gamete formation and variability

- Gametes form by meiosis, where recombination of genetic material takes place as a result of crossing over and random segregation

o In crossing over, homologous chromosomes exchange genes and so the resulting combination of alleles on chromatids differs from those originally on the parent chromosomes.

o In random segregation and independent assortment, genes on different chromosomes sort independently of each other, giving different gene combination in gametes from those of the parents.

Sexual reproduction and variability

- In sexual reproduction each female or male cell produces 4 sex cells (gametes) from the process of meiosis. Each of these sex cells is haploid (has half the normal chromosome number) and has a random assortment of genes from the parent. The genes (Mendel's alleles) are separated and the sex cells have a random assortment of dominant and recessive genes. More variability is introduced depending on which sex cells are successful in fertilisation. The resulting embryo has a completely different set of genes from either of the parents.

x Describe the inheritance of sex linked genes, and alleles that exhibit co dominance and explain why the