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Terms in this set (51)

- Enzymes have optimum temperature for activity. Activity is how fast an enzyme catalyses a reaction (rate). Enzymes can be denatured (destroyed) by higher temperature. (In investigation)
- To measure the affect of one factor others must be constant. All other variables (amount, type and environment of enzyme) must be constant.
- Low temperature= low activity of enzymes, due to the fact that enzyme and substrate both have low energy.
- High temperature= more molecules reacting due to activation energy, and an increase in reaction rate.
- Optimum (Vmax) is 40oC this is when all of the enzyme molecules are acting at maximum capacity.
- Effect of temperature directly related to the protein structure of the enzyme
- As the temperature increases the enzyme activity increase, until it reaches its optimum temperature.
- Due to the fact that the enzyme and substrate molecules are moving faster (rise in kinetic energy) and there are more collisions. (Can also look at prelim chem assignment)
- If the heat is able to break the bonds that cause the protein to fold then it destroys the active site. Therefore the substrate has nothing to bond to and is therefore denatured.
- At higher temperatures the shape of the enzymes changes, and they may be no longer able to accommodate the substrate. This causes an activity decrease, though if the temperature drops the activity will begin again.
- At VERY high temperatures, the enzyme becomes denatured - destroy the characteristic properties of (a protein or other biological macromolecule) by heat, acidity, or other effects that disrupt its molecular conformation. E.g. the chemical bonds holding the protein molecules together are broken and the shape is changed permanently. When the enzyme is destroyed it can no longer accommodate the substrate and will remain inactive even if optimum temperature is returned. It is irreversible.
Homeostasis is the process by which organisms maintain a stable internal environment-

- Blood temperature should be around 37oC and blood pH around 7.38-7.42, blood sugar should remain around 90mg/ 100mL of blood.
- Homeostasis is the process, which organisms use to maintain their optimum temperature even when affected by limits caused by changes in external environment, behaviour. They adjust this through changing their psychological process.
- Homeostasis- 'staying similar' or 'unchanging'. Refers to the 'steady state' of an organism.
- Homeostasis can occur in living and non-living things, but is more common in vertebrates.
- Homeostasis is called a self-regulation in non-living things, and homeostasis in living things.
- Receptors are constantly monitoring
- Control centre compares stimulus with the set point.
- Effectors carry the message
- Homeostasis first begun by Claude Bernard in 1859. Though he didn't call it this, a man named Walter Cannon did in 1929.
- They may be self regulating- e.g. a thermostat, which has certain vital parts:
o A system where a set value must be maintained
o A detector device, which sends feedback
o A control centre, which responds to the feedback
o A regulator, which corrects any deviations from the set value.
- Living things need to control their-
• Body temp and metabolic rate.
• Concentrations of dissolved salts and minerals
• Concentration of nutrients, e.g. glucose in blood.
• Input and output of water
• Amount of nitrogenous wastes
• O2 and CO2 concentrations.
• Removal of malfunctioning cells or foreign substances.
- These systems monitor all the activities of cells, their requirements and the wastes produced- to maintain health.
- The internal environment of cells are kept within the certain limits of the coordinating systems of the body
o Non-Living: refrigerator or lab bath: required temperature set on a thermostat. It is switched on, a sensitive thermometer (detection system) gives feedback to control centre. Activates/ turns off heater to cool and heat to get to ideal temp.
• Needs: set value, detector device (which sends feedback), control centre and a regulator.
o Living: needs a receptor, a control centre and an effector to carry out homeostatic levels. Receptor plays roll of the detector and monitors changes. Responding is done by the effector. This takes place in two stages: detection and responding.
Coordination in animals is controlled by two different systems-
- The nervous system
- The endocrine system (hormonal system)

In plants it is run by the hormone system-
- In plants the hormone system brings about coordinated functioning of organ systems.

- The feedback mechanisms are self-regulating systems that maintain a balance or homeostasis. It is any circular process where information is fed back to the central control region. E.g. the human body uses feedback mechanisms to deal with changes in body temperature.

Stage 1- Detecting changes from the stable state:
- Receptor detects changes- stimulus
- Body needs to remain in 'stable state' in order to function properly
- The changes/deviations to the stable state are a result of changes to the external and internal environment.
- These changes provoke a response called a stimulus.
- Receptors detect stimuli, to which the organism then reacts to the change.
- Internal Stimuli- Light, day length, sound, temperature, odours
- External Stimuli- levels of CO2, oxygen levels, water, wastes, etc. inside the body.
- Receptors can range from a patch of sensitive cells (e.g. tongue) to complex organs such as eyes and ears.
- If human body temp rises, the brain is stimulated by the rise in blood (using the anterior hypothalamus)
- Also when a mammal is exposed to the cold the skin receptors increase their activity sending nerve impulses to the posterior hypothalamus.
In Plants-
- Plants can detect gravity, light intensity and direction and the length of a period of darkness.

Stage 2- Counteracting changes from the stable state:
- Effectors control change.
- After the receptors detect change the organism then reacts to the change.
- The response will counteract the change in the stable state so that it is once again maintained.
- Effectors- They bring about responses to the stimuli
- Effectors can be muscles or glands- Muscles bring about change by movement, glands bring about change by secreting chemical substances.
- After detecting the rise in body temp. The hypothalamus them stimulates heat loss by increasing the blood circulation through the skin, increasing sweat and decreasing metabolic activity and muscular activity. Thus lowering body temperature.
- After detecting the drop in temperature, activity in the posterior hypothalamus stimulates the sympathetic nervous system to activate mechanisms that conserve heat.
In Plants-
- Plants after detecting and increase in concentration of fluids, release abscisic acid from chloroplasts so that there is a closing of stomates and an increase in the production of watertight resins.
− Plants need certain temperature for growth/germination of seeds.
− Land temperature changes more on land than in water.
− Plants response includes:
o Orientation of leaves vertically to reduce SA exposed to sun.
o This allows for heat absorption and supporting convection cooling
o Ability to drop leaves in cold.
o Germination of seeds after certain periods. E.g. some seed will only germinate after a certain period of cool.
o Budding increase when temperature/ length of day increases in spring.
o Closing of stomates in high temperature to reduce water loss (uses guard cells).
o Desert plants or plants which are exposed to high temperatures elicit a few responses due to temperature change. For example due to increasing temperature a desert plant will have smaller leaves which in turn decreases their surface area which leads to a decrease in water loss and solar radiation.
o An Australian example where a plant reacts to temperature change is the eucalypt. The eucalypts leaves hang down, vertical in nature. This in turn provides a large surface area for the rising sun, and at this time of the day it is generally cool in nature. When the sun is higher in the sky around midday, the ambient temperature generally increases. At this time the eucalypts leaves are still hanging vertically which in turn reduces the surface area of the leaf as well as maximising water retention. In some very dry and hot conditions the eucalypt may even close its stomates in order to stop transpiration from occurring.
1. What are the current technologies?
- ABG (arterial blood gas) analysis
o Measures the amount of oxygen and CO2 in blood.
o It evaluates how efficiently the lungs and delivering oxygen and getting rid of carbon dioxide.
o It measures the partial pressure of oxygen and carbon dioxide, oxygen content and saturation, bicarbonate content and blood pH.
o Oxygen saturation is the amount of oxygen actually combined with the haemoglobin compared to the total amount of oxygen it is actually able to combine with.
o Arterial blood is collected for this type of analysis.
o Uses electrochemical methods

Pulse Oximeter:
− A pulse oximeter is used for monitoring oxygen saturation (oxygen levels).
− It is attached to a finger and uses the transition of light through the tissues to measure oxygen saturation.
− This method has its advantages because it is painless, easy to apply, quickly to give results and non-invasive and provides continuous monitoring for patients undergoing anaesthesia or medical ventilation.
− Can also be used as a general check-up procedure to analyse O2 levels
− This is gained due to the large difference in red light absorbed by the haemoglobin compared to oxyhaemoglobin.

2. The conditions under which the technologies are used-
− To assess respiratory diseases and other conditions affecting/or may affect the lungs. E.g. pneumonia and silicosis.
− It is used to manage patients receiving oxygen therapy, mechanical ventilation, and anaesthesia, in intestine care, in accident and emergency facilities or for premature babies.
− Test of blood pH also provide information on how well the kidneys and lungs are maintaining blood pH.
− As a response to signs of low oxygen or high carbon dioxide levels.
− For diagnoses and monitoring of patients

Pulse Oximeter:
− Also used during surgeries, to monitor patients under anaesthesia.
− And used to monitor premature babies that are in neo-natal wards.
− Used in many conditions - this is because it is painless, easy to apply and quick to give results.
− Can also be used as a general check-up procedure to analyse O2 levels.
− Arteries:
o Sends from heart to body cells.
o Thick muscular walls
o No valves
o Carry blood away from heart
o Carries oxygenated blood (ex. Pulmonary artery)
o Carried under pressure (pumped) (high blood pressure)
o The pressure creates great stress in the arteries
o This gives reason to why they are thick walled, elastic and muscular.
o They have muscle fibres in them, which can contract and relax meaning they not motionless.
o The contracting maintains the pressure of the blood, so that the blood travels in spurts towards the body tissues (this also creates the pulse on your wrist or neck).
o The muscle fibres of the arteries also maintain the rate of the flow of blood.
− Veins:
o Carry blood back to the heart
o This is why they have thinner walls than arteries, less muscle and a wider diameter (large lumen).
o Valves present- Since there are no thick muscular walls to keep the blood pulsing along to prevent backward flow of blood
o Carries blood to the heart
o Carries deoxygenated blood
o Carried under low pressure: from movement via muscles as you use these muscles, they press on the veins, pushing blood through the veins
o Veins are not under a lot of stress - blood pressure is low
• CS-

− Capillaries:
o Thin, tiny blood vessels in every cell of the body, and at every entry or exit point.
o An extension of the inner layers of the arteries and veins
o Connect arteries and veins
o Thin-walled because only one cell thick
o This means that only one red blood cell can pass at a time.
o Thus, providing a very large surface area over which exchange of materials between blood and body cells can occur.
Chemical Composition of the blood as it moves around the body Tissues in which these changes occur-
− Blood receives oxygen and carbon dioxide is released.
− Blood enters via the right atrium of the heart via the vena cava (major vein)
− Blood which enters is high in carbon dioxide
− Blood is low in glucose and other nutrients; it is also high in urea, other nitrogenous wastes and various poisons.
− As the heart beats, the right ventricle pumps the blood through the pulmonary artery, to the lungs
− Where the blood gains oxygen, and loses carbon dioxide.
− The blood then enters the left atrium via the pulmonary vein. Lung tissue
− Blood receives carbon dioxide and released oxygen
− The left ventricle pumps oxygenated blood to the body through the aorta.
− The blood loses oxygen and gains carbon dioxide in all body cells, as respiration occurs. Glucose levels also drop. General body tissue e.g. Skin tissue
− Water diffuses into the blood. Some substances e.g. alcohol pass into the stomach tissue from the blood through the walls of the stomach Stomach tissue
− Digested food, amino acids, glucose- diffuse into the blood and go to the liver. Fatty acids go to the lymph. Small intestine tissue
− Glucose is regulated (added or removed) and some poisonous/unwanted substances are removed. Excess vitamins, ions, lipids are removed. Excess amino acids are removed and converted into ammonia, and then into urea, which is added to the blood.
− Poisons are also reduced, as the liver changes them to less toxic forms Liver tissue
− Water/salts/vitamins absorbed in large intestine and passed into blood. Large intestinal tissue
− Urea, excess water, salts removed from blood excreted. Kidney tissue

− Hormones are secreted directly into the blood stream. Endocrine tissue
- Determine whether the products from donated blood are a benefit or not.

The main products extracted from donated blood are:
• Red blood cells
• Platelets
• Plasma
These products are spun in a centrifuge to separate them into different products. Further products can be extracted from the plasma. The uses and further products that can be extracted are outlined by the table below:

Whole Blood To replace large amounts of blood from sever injury.
Red Blood Cells Given to patients suffering from anaemia, (iron deficiency in the blood) and in cases of severe bleeding.
White Blood Cells Given to patients with a low white blood cell count or in cases of severe bacterial infection.
Plasma Given to patients after trauma, or following after a surgical procedure.
Platelets Given to patients with severe haemorrhaging (bleeding) or bleeding due to diseases such as leukemia.
Cryoprecipitate (contains blood clotting factors) Given to patients suffering from haemophilia A. Alternatively severe bleeding.
Prothrombinex - HTTM (contains concentrated clotting factors.) Given to patients with specific bleeding disorders. These specific disorders pertain to patients who are missing certain clotting factors.
Biostate (contains factor VIII clotting factor) Given to patients with haemophilia B.
Monofix® - VF (contains Christmas factor) Given to patients with haemophilia B
Thrombotrol® - VF Given to patients in situations whereby their blood is clotting too quickly.
Albumin Administered to patients who are suffering from burns, shock due to blood loss and kidney/liver diseases.
Intagram® P Given to patients who suffer from immune disorders such as AIDS, this in turn reduces susceptibility to infections.
Hyper - immune globulins (contain - antibodies) Given to patients to treat and/or prevent specific infections such as tetanus or chicken pox.
Rh(D) immunoglobulin (Anti - D) This product prevents haemolytic disease in newborn babies of Rh negative babies. Haemolytic disease basically pertains to the mother producing certain antibodies that destroy the baby's red blood cells.
• Blood enters the right atrium of the heart via the vena cava (major vein):
• The blood is deoxygenated, and high in carbon dioxide
• It is low in glucose and other nutrients; it is also high in urea, other nitrogenous wastes and various poisons.
• As the heart beats, the right ventricle pumps the blood through the pulmonary artery, to the lungs:
• Here the blood gains oxygen, and loses its carbon dioxide.
• The blood then enters the left atrium via the pulmonary vein.
• The left ventricle pumps oxygenated blood to the body through the aorta.
• In the body, various changes occur to the blood.
• The blood loses oxygen and gains carbon dioxide in all body cells, as respiration occurs. Glucose levels also drop.
• In the LIVER:
• Levels of glucose are regulated - excess glucose is changed to glycogen, or glycogen stores are changed to glucose (if needed)
• Excess amino acids are changed to ammonia, and then to urea
• Poisons are also reduced, as the liver changes them to less toxic forms
• Levels of nutrients from digestion increase.
• Glucose, amino acids, ions, lipids and other substances from food enter the blood. The increase is through the small intestines reabsorption of food
• In the KIDNEYS:
• Salt and water levels are regulated
• All urea is removed, toxins are excreted into the urine
• The changed blood, again highly deoxygenated, then flows back to the pulmonary circuit.

Oxygen in cells
Describe current theories about processes responsible for the movement of materials through plants in xylem and phloem tissues-
Transport in Plants
o Xylem of flowering plants consists of xylem vessels, tracheids, fibres and parenchyma
o Water and minerals rise through the xylem through pressure from the roots and vacuums from the leaves.
o Phloem consists of fibres, parenchyma, sieve cells and companion cells.

Processes involved in the transpiration stream
• Kidney has a duel role-
o Excreting nitrogenous wastes
o Maintaining a water balance in mammals and fish.
o It is also an organ of filtration, reabsorption and secretion.
• When amino acids are broken down they create ammonia, which is highly toxic, very soluble and diffuses readily across cells
• In fish it is dissolved out through the gills and released into water in small amounts.
• In mammals, sharks and some bony fish liver convert ammonia to urea, which is less toxic and releases less water.
• The blood carrying the nitrogenous waste is brought from the renal arteries into the kidneys.
• Urine is formed in the cortex and the central medulla.
• The pelvis is connected to the medulla to the ureter which takes the urine to the bladder for short-term shortage.
• Depending on the environment of fish and mammals, the kidneys excrete urine in different concentrations including-
o Concentrated urine in ranges of concentrations, such as high in fish and low water in mammals.
o Freshwater fish excrete dilute urine resulting from the influx of water from their environment.
o They can also reabsorb water into the bloodstream and help overcome water balance problems resulting in an influx of water flowing into the environment.

• The primary role is osmoregulation.
• This is the regulation of salt and water levels in the body
• Fish do not excrete nitrogenous wastes through the kidneys; they use their gills
• Their urine contains mainly excess water and salts
• Mammals' urine contains urea as well as water and salts
• The kidneys ensure that the concentration of blood and interstitial fluid is constant
- The nephron is a regulatory unit; it absorbs or secretes substances in order to maintain homeostasis.
- This regulation maintains the constant composition of body fluids.
- Salts and water are adjusted to maintain fluid concentration
- Different ions also adjusted to maintain pH.
- These different processes happen in the different sections of the nephron.
- Proximal Tubule:
• Bicarbonate ions are reabsorbed into the capillaries into the blood from the nephron, hydrogen ions are secreted out. This maintains the pH of the blood.
• Drugs, such as aspirin, penicillin and poisons are secreted out of the blood
• Regulation of salts also occurs here. Sodium ions are actively reabsorbed and chlorine ions follow passively. Potassium ions are also reabsorbed
- The Loop of Henle: It has a descending limb and an ascending limb
• In the descending limb, it is permeable to water, not salt.
• Water passes out of the nephron and into the capillaries by osmosis
• In the ascending limb, the walls are permeable to salt, but not water
➢ Ascending limb is thin-walled at the bottom, and thick-walled at the top.
• Salt passively passes out into the capillaries at the bottom, thin-walled section, but is actively passed out in the top, thick-walled section.
- The Distal Tubule:
• Selective reabsorption of sodium ions and potassium ions occurs here again, to regulate the pH of the blood, and the concentration of salts.
- The Collecting Duct:
• This is the end of the nephron, and connects to the ureters.
• The walls are permeable to water only, and water is transported out accordingly to the needs of the body
• The final filtrate is called urine.
- Active transport uses energy to transport substances across a membrane it would normally not be able to cross due to a diffusion gradient or its own properties
- Passive transport is the movement of substances across a membrane without energy expenditure (this is diffusion and osmosis) - completely random.
- A kidney is made up of around a million nephrons. It is within the nephrons that the processes of filtration, reabsorption and secretion occur.
- The STRUCTURE of a nephron:
• It is a long twisted tubule made up of sections: a Bowman's capsule, connected to (1) a proximal tubule, leading to the (2) loop of Henle, which connects to (3) the distal tubule. This all joins to the collecting duct which leads to the bladder.
- The nephrons are densely surrounded by capillaries (this is to provide a large surface area for excretion).
- Three processes occur in the nephrons (kidneys):
• Filtration: Within the Bowman's capsule is the glomerulus, a dense clump of capillaries. The blood pressure here is so high that fluid and substance from the blood are forced into the Bowman's capsule, and form a fluid called the glomerular filtrate. It flows into the nephron and contains:
➢ Substances the body can reuse: Glucose, water, amino acids, etc.
➢ Wastes: Urea and poisons.
• Reabsorption: The substances the body can reuse are reabsorbed into the capillaries surrounding the nephron. E.g. Vitamins and hormones. This is active transport and requires energy. Some other substances passively re-enter the blood. E.g. water by osmosis and salts by diffusion. This occurs in the proximal and distal tubules and in the loop of Henle (discussed in detail later).
• Secretion: This is the process where the body actively transports substances from the blood into the nephron. Some toxins, such as urea, tend to diffuse back into the blood, so it must be secreted back into the nephron. It is also done to regulate salt and water levels again, or to remove additional toxins. This is active transport.
• Halophytes are plants adapted to living in salty environments. They have:
- Salt excluders on their roots
- Salt filtration system
- Excrete salt from the leaves
• Xerophytes are plants adapted to arid and dry conditions. These include:
- Thick leaves or a waxy cuticle
- Small leaves, hairy leaves
- Reflective leaf surfaces
- Vertically hanging leaves
- Thick bark to prevent wilting
Halophytes are plants adapted to living in salty environments. They use a number of processes to enable them to regulate their salt levels like:

Salt Exclusion- salt tolerant plants are often able to stop salt from entering their tissues. In most halophytes the roots are able to prevent about 95% of the salt in the soil water from entering.

Control of salt movement- Salt levels in the xylem are kept low by salt remaining in the roots or entering older parts of the plant. Xylem sap reaching young leaves and flowers (the growing points) have a very low salt concentration. Older leaves with accumulated salt drop regularly from the plant.

Salt Excretion- Leaves of some halophytes actively excrete salt. Salt glands move salt from the leaf tissues to the surface of the leaf. Here the salt crystallizes and is then blown or washed away. Some plants have leaves with salt bladders where salt accumulates. The bladders often burst, releasing their contents onto the surface of the leaf.

Osmotic Adjustment - Halophytes usually have a higher concentration of dissolved substances (solutes) in their cells than salt sensitive plants. They may maintain this by producing and storing organic compounds such as glycerol. Unlike high salt levels, these compounds are not damaging or toxic to the cells. In aquatic algae and sea grasses this helps maintain a balance between the concentration inside the plant cells and the sea water outside.

Thus plants in saline environments need to regulate their salt levels to survive because too much salt affects the functioning and health of the plant.