Maintaining A Balance

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

Aldosterone Where is it produced - Adrenal cortex of adrenal gland. When it is produced - Regulated by two mechanisms: 1. Decrease in blood volume and fall in blood pressure cause secretion of rennin in kidney. Rennin starts chemical reactions that cause the adrenal gland to release aldosterone. 2. Level of sodium ion concentration. Stored - No. Travels - From adrenal gland to kidney. Action - Causes increased active transport of sodium ions from nephron distal tubules. Water follows and is reabsorbed from the tubules. This causes concentration of solutes in blood to decrease and blood pressure rises. Suppression - Negative feedback causes decreased secretion of aldosterone. Antidiuretic hormone Where is it produced - Neurosecretory cells in hypothalamus in brain. When it is produced - When hypothalamus detects a rise in blood solutes, i.e there is a decrease in water concentration in blood. Stored - Can be stored in posterior pituitary gland. Travels - Travels in bloodstream from posterior pituitary gland to kidney. Action - In kidney it increases the permeability of distal tubules and collecting ducts to water. This increases the amount of water reabsorbed and concentration of solutes decreases. Suppression - Negative feedback causes decreased secretion of ADH.

1.9 Identify some responses of plants to temperature change a. Explain how verbalization assists

Beech tree - Tree is deciduous, leaves are dropped in winter. Reduces growth rate, less energy is needed and avoids damage to leaves. Daffodil - Plant des back leaving no parts above ground. Bulb is protected underground to survive winter and will sprout when conditions favourable. Geraniums - The plant produces smaller leaves to reduce surface area exposed to heat.Leaves have stomates and higher temperatures can lead to increased transpiration, which causes plant to dry out. Hakea - Extreme heat of fire causes seed dispersal. Seeds are released onto soil covered in ash with less ground over giving the seeds a higher chance of survival. a. Verbalization is a response whereby plants need to have been exposed to a certain degree of cold conditions before they will flower, e.g many gardeners in warmer areas of NSW remove tulips from the ground and put them on a refrigerator for a length of time in winter so when the bulbs are returned to the soil they will flower in spring.

Arteries

Carry blood away from the heart Thick elastic muscular wall with three main layers with muscle and elastic tissue. Highest blood pressure is in arteries near the heart, e.g aorta. Small bore Distribute blood away from the heart, e.g to arterioles that carry blood to capillaries. Most arteries carry oxygenated blood (except pulmonary artery) No valves

Veins

Carry blood to the heart. Thin walls with fewer elastic and muscle fibres than the equivalent layers in arteries. Lower blood pressure, insufficient to return all blood from extremities to the heart. Large bore. Return blood to heart from capillaries to venules to veins. Most veins carry deoxygenated blood (except pulmonary vein) Valves present to prevent back flow.

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

Eucalypts - Leaves hang vertically Less surface area of leaf is exposed to heat of midday sun. Vertical position means photosynthesis occurs in morning and afternoon and stomates close midday, and thus transpiration and water loss is reduced. Spinifex Grass - Leaf can coil around under Stomates on underside are protected from heat, wind etc and water loss by transpiration is reduced. Hakea Multilineata (grass-leaf hakea) - Leaves are long, thin blades Long, thin blades reduce surface area and reduces SA:V. This reduces water loss by transpiration. Carpobrotus rossii (pigface) - Leaves are thick, succulent Thick, succulent leaves store water, allowing plant to grow in arid areas and have water available when needed. Actinotus spp (flannel flower) - Leaves have dense covering of pale woolly hairs. Dense covering of wooly hairs reduces the ability of water to evaporate and move away from the plant. This decreases water loss by transpiration. Acacia spp - Have extensive root system with root nodules. Extensive root system increases ability to absorb water when water is available. Oleander - Deep root system below the water table. Deep root system allows to tap into the water table providing water, even if the surface is dry.

2.4 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

Lungs - Carbon dioxide Carbon dioxide increases in concentration as it diffuses into the lungs from the blood returning from respiring body cells. Lungs-Oxygen Oxygen decreases in concentration it diffuses out of the alveoli in the lungs into the blood to be taken to cells for respiration. Villi of small intestine - Amino acids and glucose Glucose and amino acids decreases in concentration as they diffuse from the small intestine into the blood to be taken away to be used by the body. Liver - Glucose Glucose concentration can decrease in the liver when there is too much glucose in the bloodstream and the glucose is removed to be stored as glycogen. Glucose concentration can increase in the liver when there is not enough glucose in the blood for maintaining stable body conditions. Kidneys -Water Water can be removed from blood or reabsorbed back into blood during the filtration process in the kidneys. Osmoregulation maintains a constant water balance in the body. Kidneys - Nitrogenous Waste Most mammals produce urea as the main nitrogenous waste. It is formed when excess amino acids accumulate after the digestion of proteins and when cells metabolise proteins into amino acids. The excess amino acids cannot be stored and are taken to the liver where they are deaminated. The concentration of urea increases in the kidneys as it is filtered from the blood and accumulated to be excreted. Glands - Hormones Endocrine glands secrete hormones directly into blood, e.g hypothalamus, pituitary gland, thyroid gland, pancreas, ovaries, testes. The hormone travels around the body in the blood until reaches the target cell tissue.

2. Plants and animals transport dissolved nutrients and gases in a fluid medium. 2.1 Identify the form(s) in which each of the following is carried in mammalian blood: - carbon dioxide - oxygen - water - salts - lipids - nitrogenous wastes - other products of digestion

Substance / Form carried in Mammalian Blood Carbon Dioxide / Carbon dioxide travels in different forms in the blood - around 7% carbon dioxide dissolves directly in the plasma, about 23% combines with haemoglobin forming carbaminohaemoglobin and about 70% forms hydrogen carbonate ions (HCO-3) and travels in the plasma. Oxygen / Oxygen combines with haemoglobin to form oxyhaemoglobin in red blood cells. Water / Water travels in plasma as water molecules. Salt Salts travel as either positive or negative ions, e.g potassium ions (K+) Lipids / Many lipids are water-insoluble and only travel in the blood when they are coated with proteins becoming lipoproteins and high-density lipoproteins (HDL) or low-density lipoproteins (LDL). Nitrogenous Waste / The nitrogenous waste is ammonia, but as this is toxic most mammals convert ammonia to urea. The conversion occurs in the liver and the kidneys filter the urea from the blood. Other Products of Digestion / Many products of digestion are soluble and travel dissolved in the plasma, e.g amino acids, glucose, vitamins.

1.6 Outline the role of the nervous system in detecting and responding to environmental changes a. Describe the stimulus-response pathway and how it enables the nervous system to respond to environmental changes.

The stimulus-response pathway consists of the steps: stimulus → receptor → central nervous system → effector → response. This pathway allows a change in the environment, e.g drop of air temperature to be detected by receptors, e.g. thermoreceptors in the skin. The receptors pass a nervous impulse to the central nervous system, which can cause a reflex action to occur, or the brain can interpret the information and a conscious decision can be made. A nervous impulse is sent to the effector, e.g. muscle or gland and the effector carries out the response, e.g shivering to increase body temperature. Thus the pathway allows the nervous system to respond to environmental changes.

Capillaries

Thin-walled blood vessels, e.g link arteries to veins. Walls are only a single cell in thickness with no elastic or muscular fibres. Small diameter causes high frictional resistance, restricts blood flow and lowers blood pressure. Bore is diameter of one red blood cell. Exchange vessels when chemicals, e.g gases exchange between blood and interstitial fluid surrounding cells. Gas exchange occurs, e.g oxygen from blood into tissues and carbon dioxide from tissues into blood.

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

a. A lot of energy is devoted to maintaining a constant internal environment, as the chemical reactions that support the processes of life require specific conditions. If conditions, e.g temperature, pH, water concentration do not remain relatively stable, the reactions will stop and life could stop.

3.5 Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney a. What is the difference between active and passive transport? b. Describe active and passive transport in the mammalian kidney.

a. Active transport requires an input of energy for the movement of materials across a cell membrane while passive transport does not require an input of energy for movement across a membrane, e.g osmosis and diffusion. b. Pressure in the glomerulus causes water, ions and small molecules to filter into Bowman's capsule. Reabsorption of glucose, amino acids and inorganic salts occurs by active transport. As these solutes move out of the nephritic filtrate, water follows by osmosis. Active transport of sodium ions causes more osmosis and the levels of salt and water are thus adjusted to maintain homeostasis.

2.5 Outline the need for oxygen in living cells and explain why removal of carbon dioxide from cells is essential a.Explain why living cells need oxygen. b.Explain why the removal of carbon dioxide from cells is essential.

a. All living things use the process of respiration to release energy to be used by the cells to maintain life processes. Aerobic respiration uses oxygen in the equation: Glucose + oxygen → carbon dioxide + water + energy Thus all living cells that respire aerobically require oxygen to survive. b. Carbon dioxide is produced as a waste product of respiration. An accumulation of carbon dioxide causes a drop in the pH. This makes blood acidic and impairs metabolic reactions and the action of enzymes. Thus the removal of carbon dioxide is essential to maintain homeostasis.

1.8 Compare responses of named Australian ectothermic and endothermic organisms to changes in the ambient temperature and explain how these responses assist temperature regulation a. Name an Australian ectotherm and describe how it responds to changes in the ambient temperature to control its body temperature. b. Name an Australian endotherm and describe how it responds to changes in the ambient temperature to control its body temperature.

a. An Australian ectotherm is the netted dragon, which is a desert lizard. It lies in the sun to absorb warmth to heat its body its until body temperature is around 36°C. It will then retreat to its burrow to stop becoming too hot. b. An Australian endotherm is the red kangaroo. If the temperature becomes too hot it will pant and lick its forelimbs, relying on the evaporation from the body surface for cooling.

2.3 Compare the structure of arteries, capillaries and veins in relation to their function a. Explain why arteries need thicker layers of elastic tissue and muscle fibres. b. Explain why it is incorrect to say that arteries carry oxygenated blood and veins carry deoxygenated blood.

a. Arteries take blood away from the heart while veins take blood to the heart. There is high blood pressure in arteries and the structure of the artery needs to be able to withstand the high pressure as well as the changes in pressure because of the rhythmic pumping of the heart. The thicker layer of elastic tissue and muscle fibres in arteries allow the vessel to expand when under pressure and then contract again. Veins are under less pressure and many have valves to keep the blood flowing in one direction as the pressure could not return the blood to the heart. b. Most arteries carry oxygenated blood and most veins carry deoxygenated blood. However, the human circulatory system is a double system with the right side of the heart pumping blood to the lungs and the left side of the heart pumping to the body. This means that the pulmonary artery carries deoxygenated blood and the pulmonary vein carries the oxygenated blood to the heart.

3. Plants and animals regulate the concentration of gases, water and waste products of metabolism in cells and in interstitial fluid. 3.1 Explain why the concentration of water in cells should be maintained within a narrow range for optimal function a. Explain why a change in the concentration of water in cells can have serious consequences on cell metabolism.

a. Cell metabolism is controlled by enzymes. Each enzyme requires specific conditions for optimal efficiency, e.g specific pH, temperature, ion concentrations. Thus a change in the concentration of water in cells could interfere with the functioning of enzymes and metabolism would be disrupted.

3.4 Explain why the processes of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms a. Explain why many organisms do not rely on diffusion and osmosis as the only processes to remove nitrogenous wastes.

a. Diffusion and osmosis are passive processes and will not occur unless a sufficient concentration gradient is present. These processes can also be quite slow. Large, active, multicellular animals quickly accumulate toxic levels of nitrogenous wastes and thus need other mechanisms, e.g ultrafiltration in the kidneys to maintain suitable concentrations of water and solutes for removal of wastes and efficient metabolism. Cause - Diffusion and Osmosis require no energy Effect - Slow processes Cause - Movement from High → Low Effect - Equilibrium reached Diffusion and Osmosis are inadequate in removing wastes because the process is slow and only continues until equilibrium is reached. This means that not all wastes are removes from the blood. Glucose : Diffusion, Active transport Water : Osmosis Sodium salts : Osmosis, Active transport

3.8 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 a. Define enantiostasis. b. Describe the main features of an estuarine environment.

a. Enantiostasis is the maintenance of metabolic and physiological functions in response to variations in the environment. b. An estuary is the region where fresh water meets salt water such as the tidal mouth of a large river or coastal inlet. Organisms present in estuaries include mangroves, seagrasses, marine worms, oysters, mussels, seahorses, crabs, prawns, fish, wading birds, gulls etc.

1.1 Identify the Role of Enzymes in Metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates. a. Describe the role of Enzymes in metabolism. b. Describe the chemical composition of enzymes. c. Explain how the lock and key model illustrates the specificity of enzymes on substrates. d. Outline how this model has been modified e. List the factors that affect enzyme activity.

a. Enzymes are organic catalysts that control the rate of reactions in the body. Each enzyme is specific for a specific reaction. b. Enzymes are proteins made of the elements : Carbon, Oxygen, Hydrogen, and Nitrogen. Proteins consist of long chains of amino acids held together by peptide bonds. c. The shape of the enzyme and the active site on the enzyme have a specific shape which fits onto the substrate forming an enzyme-substrate complex. The reaction occurs and the enzyme breaks away from the products(s). d. The lock-and-key model (created by Emil Fischer in 1894) has been modified to the induced-fit model (created by Daniel Koshland in 1958). Analysis of the shapes of molecules shows that the active site is more flexible than a 'keyhole' and can slightly alter its shape to fit more closely with the substrate. e. • Temperature • Substrate - The amount of substrate present • pH • Coenzymes - Presence of coenzymes or cofactors • Metals -Presence of heavy metals e.g mercury, lead, zinc. T.S.p.C.M

2.2 Explain the adaptive advantage of haemoglobin a.What is Haemoglobin? b. Haemoglobin is often described as a 'respiratory pigment'. What does this mean?

a. Haemoglobin is a protein made up of four polypeptide chains (called globins) and each is bonded to a haem (iron containing) group. Each haem is a red pigment molecule and the iron is lost from the body. Haemoglobin molecules each contain four haem units, giving one haemoglobin molecule the ability to bond with four oxygen molecules and so far more oxygen can be carried in the blood cells by haemoglobin (1000 million molecules of oxygen) that could be carries dissolved into plasma. b. A respiratory pigment is a compound that gives colour, e.g haemoglobin is responsible for the red colour of blood, and that is involved in respiration, e.g haemoglobin carries oxygen needed for respiration. Explain why the presence of haemoglobin in the red blood cells of mammals is an adaptive advantage. Oxygen can combine with haemoglobin to form oxyhaemoglobin. This increases the oxygen-carrying capacity of the blood. Mammals are endotherms and use the heat from internal metabolic processes to maintain body temperature, e.g oxygen and glucose are used in respiration to release energy in the form of ATP and heat. It is therefore an adaptive advantage for mammals to have haemoglobin in their red blood cells to carry more oxygen to release more energy to maintain body temperature, ensure optimum conditions for chemical reactions and for an active life to find food, find a mate, and care for offspring. Another adaptive advantage of haemoglobin is that its capacity to release oxygen increases when carbon dioxide is present.

1.5 Explain that homeostasis consists of two stages: - detecting changes from the stable state - counteracting changes from the stable state a. Identify the two stages of homeostasis. b. Identify the body processes that are controlled by homeostasis.

a. Homeostasis consists of two stages - detecting changes from the stable state and counteracting changes from the stable state. b. Changes from the stable state are detected by receptors. There are internal and external receptors. Receptors in the sense organs detect changes in the external environment. Internal receptors are part of a feedback system to help maintain homeostasis in the body.

1.4 Describe homeostasis as the process by which organisms maintain a relatively stable internal environment a. Define Homeostasis b. Identify body processes that are controlled by homeostasis

a. Homeostasis is defined as the maintenance of a relatively stable internal environment. b. Conditions controlled by homeostasis include Body temperature, pH, Water concentration, Salt concentration, Sugar levels, levels of dissolved gases, e.g Oxygen and carbon dioxide. B.O.S.S + p.W

3.3 Identify the role of the kidney in the excretory system of fish and mammals. a. Compare the role of the kidney in mammals, freshwater fish and saltwater fish.

a. Mammal Kidney - An excretory organ that filters blood and removes nitrogenous wastes. Structure - Many nephrons Filtration - High blood pressure in glomerulus forces ultrafiltration. Urine produced - Amount and concentration depends upon water intake and activities. Saltwater Fish Kidney - An excretory organ that filters blood and removes nitrogenous wastes. Structure - Simple structure with few small glomeruli. Filtration - Low filtration rate. Urine produced - Small quantity urine produced. Freshwater Fish Kidney - An excretory organ that filters blood and removes nitrogenous wastes. Structure - Simple structure with many large glomeruli. Filtration - High filtration rate. Urine produced - Large amounts of very dilute urine.

1.7 Identify the broad range of temperatures over which life is found compared with the narrow limits for individual species a. Identify the range of temperatures over which most life is found and give an exception to this range. b. Use an example to show how some species can only survive in a very narrow temperature range.

a. Most organisms live in environments with temperatures between 0°C and 45°C. However, organisms have been found at the poles with temperatures below -70°C and around black smokers in oceanic trenches with temperatures above 200°C. b. Organisms that live in coral reefs can only survive in a very narrow temperature, e.g staghorn coral Acropora spp. A change in temperature will threaten the existence of the coral.

3.2 Explain why the removal of wastes is essential for continued metabolic activity a. Identify the main metabolic wastes products and discuss why they need to be removed from the body.

a. The main metabolic wastes are carbon dioxide, excess salts, excess water and nitrogenous wastes (e.g urea, ammonia or uric acid). An accumulation of wastes can be toxic to the body or can disrupt metabolic activity. For example , high levels of ammonia or urea will kill cells and excess water will change concentrations affecting enzyme activity.

3.6 Explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition a. Explain how filtration and reabsorption in the kidney maintain the concentration of water and salts in the body.

a. Ultrafiltration occurs when high blood pressure in the glomerulus forces water, ions and small molecules into Bowman's capsule. Components that are needed by the body are then selectively reabsorbed into the bloodstream in the tubules. By controlling reabsorption into the bloodstream, the salt and water levels of body fluids are controlled.

2.6 Describe current theories about processes responsible for the movement of materials through plants in xylem and phloem tissue a. Identify the parts of vascular tissue in plants and their functions. b. Describe the process for movement of materials in xylem tissue. c. Describe the process for movement of materials in phloem tissue.

a. Vascular tissue in plants consists of xylem, which conducts water and mineral ions up the plant from roots to leaves and phloem which translocates the products of photosynthesis and other organic products both up and down the plant. b. Xylem is involved in the movement of water and mineral ions up the plant. Water enters the root by osmosis and then transpiration pull draws the water up the stem. Cohesion between the water molecules causes the water to form a continuous steam up the plant and 'pulls' the water up. Adhesion between the water molecules and the walls of the xylem vessels also helps draw water up the plant. c. Phloem is involved in the translocation of organic compounds both up and down the plant in a 'source-to-sink' movement. At the 'source' (e.g leaf) phloem loading involves sugars moving by active transport into the sieve tube. Water follows due to osmosis and thus raises the pressure in the tube. Pressure causes the contents to flow to the sink. At the sink (e.g storage or growing area) the sugars are unloaded by active transport. Water then moves out by osmosis and moves to the xylem.

1.2 Identify the pH as a way of describing the acidity of a substance a. What is PH?

a. pH is a measure of the acidity of a substance. The scale ranges from 1 (acid) to 7 (neutral) to 14 (base).