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


Biology (MAINTAINING A BALANCE) Note on 3. Plants and animals regulate the concentration of gases, water and waste products of metabolism in, created by shaycrystal4 on 15/11/2013.
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Explain why the concentration of water in cells should be maintained within a narrow range for optimal functionWhy water is important -75% of cells are made from water1. Water is the solvent for all metabolic reactions: the transport of materials takes place mainly in water solutions (cytoplasm, blood, phloem)2. Water is involved in life chemistry; water is the reactant/product of many reactions (photosynthesis & cellular respiration3. Water is vital in temp regulation: it takes much energy to impact the temp of water, enabling organisms to maintain homeostasis and sweating is a major cooling function that relies on water (as it absorbs much heat when evaporated)4. Water supports and cushions cells and organs: some organisms rely on water for body support (non-woody plants pump their cell vacuoles full of water to stand up right, worms rely on hydraulic pressure of water in their tissues to support their body and maintain shape)-The concentration of water affects the concentration of dissolved substances, thus affecting metabolic activity because most substances (that are water soluble) rely on diffusionIf the concentrations of water and salt are not kept constant and at correct levels then osmosis may cause problems. Cells could lose water and dehydrate, or gain too much water and be damaged. This would therefore affect all the points listed above.

Explain why the removal of wastes is essential for continued metabolic activityWastesThe productions of metabolic reactions and are toxic to cells; because the chemicals (when dissolved in water) can be acidic/alkaline and therefore affect the pH and reduce enzyme activity. The main wastes are:-Carbon dioxide -produced by cellular respiration-Nitrogenous wastes (containing nitrogen)-produced from the metabolism of proteins.The tree main compounds are:   -ammonia (most alkaline)-fish and aquatic invertebrates   -uric acid-birds, reptiles and insects   -urea-mammals and amphibiansHow wastes impact metabolic activity-affects the balance of substances that cells require for metabolic reactions (reaction equilibrium). This is due to most substances relying on osmosis and diffusion. So not having the right balance affects reaction rate.-if not removed immediately, it slows down reaction rate then may kill the cell-changes pH

Explain why the process of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms-Fish can excrete highly toxic ammonia because they rely on constant diffusion of ammonia from the blood in their gills into the water that surrounds them. -In the terrestrial environment, organisms also rely on diffusion for carbon dioxide. -But, nitrogenous wastes are not gaseous and need to be excreted in a water solution-So terrestrial organisms excrete their nitrogenous waste in the less toxic form of uric acid and area.-Excretion is via the kidneys, diffusion and osmosis is not adequate to achieve this.-For diffusion to achieve this it would take large amounts of water to be excreted too and no terrestrial animal can afford to do this.

Identify the role if the kidney in the excretory system of fish and mammals-the kidney filters the blood and removes nitrogenous wastes from the body. It filters wastes into:  -ammonia (fish and aquatic invertebrates)  -uric acid (birds, reptiles and insects  -urea (mammals and amphibians)

Explain how the process of filtration and reabsorption in the mammalian nephron regulate body fluid composition -There is about 1 million nephrons per kidney-Each nephron is a tangle of blood vessels and renal tubules (tiny tubes)Filtration: the process of water and many dissolved substances (sugars, salts and urea BUT NOT any cells or blood proteins) leave the blood and flow into renal tubules.-Removes some water, small dissolved molecules and urea from blood into renal tubules-This happens due to the 'leaky' walls of the glomerulus and the blood being under high pressure-occurs in Bowman's Capsule from blood travelling through the GlomerulusReabsorption: the process of any useful substances (sugars and amino acids) are absorbed back into blood. Water and salts are also reabsorbed, but in varying quantities; (the body is adjusting the water balance for homeostasis)-Occurs after filtration to move useful substances back into blood-Achieved by:   -active transport of sugars, amino acids & salts from the renal tubules back into blood. Requires energy to cross the cell membrane against a concentration gradient.  -osmosis then occurs to move water across tubules into blood (occurs passively) -Occurs in Loop of Henley-urea is not absorbed back into blood-urea and some water continue along tubule. (URINE)-Urea + water = urine  >  ureter  > bladder  >  urethra 

Marine fish: -Tissues: loss of water by osmosis (mainly gills)-Kidneys produce small amounts of urine to save water-Gills excrete ammonia, carbon dioxide and excretes excess salt-Constantly drink to replace water (but get salt too)Fresh water fish:-Tissues: gain water by osmosis (mainly through gills)-Kidneys produce a lot of dilute urine to remove water from body-Gills excrete ammonia and carbon dioxide, and actively absorb salts-Does not drink

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

Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidneyThe nephron uses active transport to overcome the inadequacies of diffusion and osmosis of nitrogenous wastes. -Active: when energy is required to move materials across a cell membrane.-Passive: requires no energy e.g. diffusion and osmosis-Pressure in glomerulus causes water, irons and small molecules to passively filter into Bowman's capsule.-Reabsorption of nutrients (glucose, amino acids, inorganic salts) is actively moved back into blood.-As this happens, water follows by osmosis (salt and water homeostasis)-Excess salts are then actively moved to blood to balance salt levels. Water follows due to osmosis.The process of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes (in some organisms) because nitrogenous wastes are not water soluble and cannot move across a semi-permeable membrane with diffusion osmosis. 

Gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidneyKIDNEYstructure: contains about 1 million nephrons which filter blood.function and nitrogenous wastes: removes urea from blood.other functions: maintains body's balance of salts, sodium, potassium + releases hormones that regulate blood pressure and red cell production.how often it occurs: all the time; 1.5-.5 litres of urine/dayfiltration and absorption: does bothRENAL DIALYSISstructure: Haemodialysis (process of renal dialysis) occurs when patient is attached to machine that circulates blood through semi-permeable filters that extracts toxins from blood. -Takes 3-4 hours. -Dialysers consist of three parts: compartment for blood, compartment for dialyse, semi-permeable membrane separating the two. function and nitrogenous wastes: removes urea from blood.other functions: concentrations of desired solutes in blood can be adjusted by manipulating the solutes in the dialysis fluid (diffuses across)how often it occurs: Works quicker than peritoneal dialysis; is done 3-4 hoursfiltration and absorption: only filters; so dialysis fluid has same levels of dissolved nutrients and water to maintain homeostasis.

Gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney Kidney Renal Dialysis  Structure Consists of about 1 mil nephrons which filter the blood Haemodialysis occurs in hospital. Machine circulates blood through semipermeable filters that remove toxins from blood. Takes 3-4hrs.  Dialysers have three parts: compartment for blood, compartment for dialyse, a semipermeable membrane separating the two. Function and nitrogenous wastes Removes urea from blood Removes urea from blood Other functions Maintains body's balance of various salts and releases hormones that regulate vital functions including blood pressure, red blood cell production  Concentrations of desired solutes can be adjusted by modifying the dialysis fluid to maintain natural concentration for healthy food. How often it occurs Each day two kidneys excrete about 1/5-2.5 litres of urine Haemodialysis works more quickly than petrineal dialysis, can be done in short sessions (3-4 times weekly), while petrineal must be done daily. Filtration and reabsorption Filters and reabsorbs required materials Filtration but no reabsorption 

Outline the role of hormones, aldosterone and ADH (anti-diuretic hormone) in the regulation of water and salt levels in bloodAldosterone:-Created from: is a steroid hormone secreted by adrenal gland-Function: regulates transfer of sodium and potassium ions in kidney-How: when sodium levels are low, aldosterone is released into blood, causing more sodium to be actively transported into blood from nephron. Water follows by osmosis -Result: homeostatic balance of blood pressure + concentrated urine.Anti-diuretic hormone (ADH/vasopressin) :-Created from: Hypothalamus but stored and released from pituitary gland.-Function: controls water reabsorption in nephron-How: when levels of fluid in blood drop, hypothalamus causes pituitary gland to release ADH. This increases permeability of collecting ducts to water, allowing more water to be absorbed from urine into blood. When there's too much fluid in blood, heart causes hypothalamus to reduce production of ADH; decreasing amount of water reabsorbed in kidney. So lower blood volume and more dilute urine. -Result: Various concentration of urine + balance of water/pressure in blood.

Present information to outline the general use of hormone replacement therapy in people who cannot secrete aldosteroneHypoaldosteronism (hypo= under, aldosterone= hormone), is a condition where people fail to secrete aldosetrone. -Addison's disease is a disease with these symptoms which include high urine and low blood volume (low blood pressure), this may result in heart failure.  -Causes:  Adrenal gland is in two parts; mudella and cortex. The cortex produces Mineralocorticoids. These hormones, which include aldosterone, maintain your body's balance of sodium and potassium to keep your blood pressure normal. Addison's disease is caused when the adrenal gland fails to produce this hormone.  -Treatment: This may be tested by a blood test which tests salt levels. The replacement hormone, fludrocortisone (florine F), is used to treat this. But the patient must still be carefully monitored to avoid fluid retention and high blood pressure.   -Benefits of fludrocortisone: regulates blood pressure   -Disadvantages of fludrocortisone: must be closely monitored often and body becomes dependant on this, resulting in the body not needing to produce aldosterone.

Analyse information from secondary sources to compare and explain the difference in urine concentration to terrestrial mammals, marine fish and freshwater fishMARINEFRESHWATERWater taken by 'drinking; salt waterSome water taken with foodWater lost through gills by osmosisWater uptake through the gills by osmosisSalts excreted by active transportSalts taken up into gills by active transport Scales and mucus secretion make skin fairly impervious to waterScales and mucus secretion make skin fairly impervious to waterConcentrated urineContinuous production of dilute urine

Use available evidence to explain the relationship between the conservation of water and the production and excretion of concentrated nitrogenous wastes in a range of Australian insects and terrestrial mammals

Define enantiostasis as the maintenance of metabolic and physiologival functions in response to variations in the environment and discuss its importance to estuarine organisms in maintaining appropriate salt concentrations






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