With reference to specific examples and mechanisms assess the significance of homeostasis to the human body.
WITH REFERENCE TO SPECIFIC EXAMPLES AND MECHANISMS ASSESS THE SIGNIFICANCE OF HOMEOSTASIS TO THE HUMAN BODY What is homeostasis? According to the 'Oxford Colour Medical Dictionary, Third Edition' homeostasis is the "the physiological process by which the internal systems of the body (e.g. blood pressure, body temperature, acid-base balance) are maintained at equilibrium, despite variations in the external conditions" Homeostasis is the maintenance of a stable internal environment within tolerance limits, this is the restricted range of conditions where cellular operations effectively work at a consistent rate and maintain life. These conditions include temperature, blood glucose levels, pupil diameter control and many more. Homeostasis actually means 'unchanging', but that is not a true description of biological systems. DYNAMIC EQUILIBRIUM is a more accurate description. (1) "An amoeba, a single celled organism, needs to be able to take in oxygen, food and nutrients and to excrete waste products. It needs a constant state of hydration and a controlled temperature for a happy life. Man is complex and multicellular but each cell has the same needs as the amoeba and we have developed complex mechanisms to provide each cell with all that it needs" (2) The human animal is a very complex multi-cellular organism in which the maintenance of life depends upon various
Diabetes Mellitus, common disorder of metabolism in which the amount of glucose, or sugar, in the blood is too high, a condition known as hyperglycaemia.
Diabetes Mellitus, common disorder of metabolism in which the amount of glucose, or sugar, in the blood is too high, a condition known as hyperglycaemia. CAUSES Diabetes develops either because the body's pancreas is not producing enough of the hormone insulin to metabolize glucose, or because the insulin fails to act on receptor cells in the blood. When blood glucose rises above a certain level, it spills over into the urine. The condition, which may be hereditary, affects roughly 3 per cent of men and 2 per cent of women; up to half of the affected population may not have been diagnosed. Though there is no cure for diabetes mellitus, proper insulin and other therapy together with a correct diet enable most patients to live virtually normal lives with minimal side effects, though their mortality rate is higher. EFFECTS Moderately raised blood glucose levels can eventually cause kidney failure; damage to vision from ruptured blood vessels in the eyes; and restricted blood flow to the limbs, which may lead to gangrene and subsequent amputation. Diabetes mellitus is also associated with a risk of coronary heart disease that is two to three times higher in men, and four to five times higher in women before the menopause. The risk of a stroke is increased two to three times. Untreated, the disease can lead to coma and death, which was the usual outcome before the
INVESTIGATION INTO THE EFFECTS OF USING DIFFERENT RESPIRATORY SUBSTRATES ON THE RATE OF ANAEROBIC RESPIRATION OF YEAST
A2 Biology Coursework INVESTIGATION INTO THE EFFECTS OF USING DIFFERENT RESPIRATORY SUBSTRATES ON THE RATE OF ANAEROBIC RESPIRATION OF YEAST INTRODUCTION Yeasts are single celled organisms like bacteria, their name saccharomyces means `sugar fungi`, but unlike fungi they do not grow hyphae. Yeasts are commonly found wherever sugar occurs. It has been used for thousands of years to ferment sugar into ethanol i.e. alcohol. Yeast added to dough ferments the sugar in the dough to produce carbon dioxide. This makes the dough rise. Aerobic respiration releases far more energy than anaerobic respiration, this is because it completely oxidises glucose into carbon dioxide and water. Reducing sugars such as glucose and fructose are readily oxidised. When this reaction occurs the sugars lose electrons to another substance, which is said to be reduced. Some disaccharides are not easily oxidised, notably sucrose, these types of sugars are non-reducing. Monosaccharides combine by a condensation reaction, and they can be turned back into their single units by hydration. When yeast acts upon a disaccharide it converts it to a monosaccharide so it becomes easier to oxidise. This suggests that it will take longer; therefore the dissacharrides will have a slower rate. Sucrose is made up of fructose and glucose, and lactose is made up of glucose and galactose. The higher the
Beetroot pigments
Assessed Practical Plan I plan to investigate the effects of varying temperature on the movement of pigment molecules across a membrane, travelling out of beetroot cells. Aim: The aim of this investigation is to determine the effect that temperature has on the rate of diffusion of beetroot pigments when slices of beetroot are placed in various temperatures of water. Background Knowledge: The pigments found in beetroot are known as betalain pigments. Some areas of a beetroot may contain more pigment molecules than others. These molecules appear to be polar molecules as they are soluble in water. Molecules which have groups with dipoles are said to be polar. They are usually attached to water molecules. They also have dipoles, and these molecules are hydrophilic, and tend to be soluble in water. The process by which the betalain molecules leave the cell, can be explored by considering the following: * Simple Diffusion * Facilitated Diffusion * Osmosis * Bulk Transport * Active Uptake We can eliminate the possibility that betalain pigments travel by osmosis, since osmosis only involves the movement of water molecules, whereas in this experiment we are researching the movement of beetroot pigment molecules. Also, the possibility of the betalain pigments travelling through the membrane by active uptake or bulk transport can be discarded, as both of these processes
Write a comparative outline of gaseous exchange in a protozoan, an earthworm and a bony fish
Write a comparative outline of gaseous exchange in a protozoan, an earthworm and a bony fish (20) All organisms need exchange and transport systems. The gaseous exchange requirements increases as the organism increases in size and complexity. Demands for water, oxygen and nutrient molecules increases with the size. Acellular organisms are active in wet conditions only. Their surface is permeable to oxygen, carbon dioxide and water. They have a large surface area to volume ratio, and diffusion distances in their body are small. Annelida, such as the earthworm, have long, thin, segmented bodies, consisting of three different layers of cells. The surface area to volume ratio is quite large, and diffusion distances are long. Chordates, such as fish, are also made up of three layers of cells. Their surface area to volume ratio is small, and the diffusion distances are very large. In both earthworms and fish, an efficient transport system, containing haemoglobin, is available to carry oxygen around the body. The surface area to volume ratio is a way of expressing the relationship between these parameters as an organism's size changes. Exchange of materials often occurs through the process of diffusion; in which dissolved molecules or other particles move from areas of higher concentration to areas of lower concentration. Generally, large organism's use more oxygen
The Effect Of Glucose Concentration On The Activity Of Various Yeasts
The Effect Of Glucose Concentration On The Activity Of Various Yeasts Aim / Prediction - I intend to investigate what effect, if any, varying concentrations of a glucose solution has on the activity of two different types of yeasts. I predict that yeast activity will continue to rise as the concentration of the glucose solution increases, but will maybe have an optimum point at which the yeast can no longer withstand the high concentration in glucose. This applies to both of the yeasts, although I think that bread-making yeast will be more tolerant of glucose than brewers yeast. There will be a positive correlation between glucose concentration and yeast activity. Null Hypothesis (HO) - Varying glucose concentrations will have no effect on yeast activity. Alternative Hypothesis (H1) - Varying glucose concentrations will have no effect on yeast activity. Background - Yeast is any of a number of microscopic, unicellular fungi important for their ability to ferment carbohydrates in various substances. Most cultivated yeasts belong to the genus Saccharomyces; those known as brewer's yeasts are strains of Saccharomyces cerevisiae. Yeasts are used generally in the making of bread and alcohol, but their cultivation and use in large quantities are used industrially in a wide range of fermentation processes. Glucose Carbon Dioxide + Ethanol The yeast metabolises the
Investigate the water potential of celeriac.
Aim Investigate the water potential of celeriac. Apparatus Celeriac - this is the specimen that we will be finding the water potential of. .00 mol dm-3 sucrose solution - this will be placed in the test tube in which the experiment will take place. We will dilute the solution to produce a range of concentrations. 0.0ml Graduated Pipettes (x2) - I had a choice of 5.0ml, 10.0ml and 20.0ml graduated pipettes. I chose this size pipette because it is time efficient and accurate at the same time. It is an accurate piece of equipment because as opposed to standard pipettes, this graduated pipette has 0.1ml graduations to ensure the utmost accuracy. One pipette will be used for water and one will be used for sucrose solution. 250ml Beakers (x2) - these will be used to hold water and the 1.00 mol dm-3 sucrose solution in a safe environment. Cork Borer - this will be used to cut the precise shape of the celeriac. This will also ensure that the surface area to volume ratio is constant throughout the experiment. Razor - this will be used to cut the pieces of celeriac to a precise length. Ruler - this will be used to measure the length of celeriac that will be used in the experiment. Scales - they will be used to measure the mass of celeriac before and after the experiment with accuracy. Therefore, the mass increase/decrease can be calculated after the experiment. These scales
Write an essay on the functions of proteins in plants and animals
Write an essay on the functions of proteins in plants and animals Proteins are polymers of monomers called amino acids. Amino acids contain hydrogen, carbon, oxygen and nitrogen. When amino acids are linked together, they form polypeptide chains and bonded together by peptide bonds. There are different structures of polypeptides primary, secondary, tertiary and quaternary. The primary structure is a straight chain of polypeptides. Secondary structure is the polypeptide chain coiling to form an ? helix or the polypeptide chain linking together to form a ß pleated strand. In an ? helix hydrogen bonding forms in the secondary structure between the NH group of one amino acid and the CO group of another amino acid. In a ß pleated strand hydrogen bonding occurs between the CO and NH groups of one amino acid residue of one chain and the NH and CO group of another chain. The further folding of the polypeptide chain is known as the tertiary structure. In this structure the folding and coiling of the chain is irregular. This causes the types of bonding between the amino acid residues to vary. The quaternary structure consists of more than one polypeptide chain this structure is found in haemoglobin. The bonding between different groups in this case can vary depending upon the functional groups present. If hydrogen and oxygen bind to another hydrogen and oxygen of another R group the
Effect of Surface Area On The Rates Of Transpiration
Effect of Surface Area On The Rates Of Transpiration Aim... Compare the effects of a named factor (surface area) on the rates of Transpiration of two different plant species. Transpiration is the evaporation of water vapour from plants; it takes place at three sites. * Stomata: Occurs in leaves and herbaceous stems, and amount for 90% of all water loss. * Cuticle: A wavy external layer on plant surfaces which serves to limit water loss through cell walls, although up to 10% of water nevertheless escapes by this route * Lenticels: Areas of loosely packed cells on the surface of woody stems through which gas exchange, and therefore water loss, takes place. Most of the water entering a plant does so via the root hairs. It travels across the root cortex to the xylem, ascends in the xylem to the leaves and is lost by evaporation from the surface of the mesophyll cells before diffusing out through the stomata. This process is called transpiration. Apparatus... Potometer Short Rubber Tubing Calibrated Capillary Tube Gas Syringe Leafy shoots X2 (Specie living in wet environment, and a Specie living in dry environment) Petroleum Jelly Method... * A leafy shoot is cut under water to prevent air entering the xylem. Care taken not to get water on the leaves. * The potometer is filled completely with water, making sure there are no air bubbles. * Using a rubber tube
The Economic Importance of Polysaccharides is Dependant on Their Chemical Structure
"The Economic Importance of Polysaccharides is Dependant on Their Chemical Structure" Polysaccharides are long, chain carbohydrates therefore they are insoluble in water. They contain thousands of glucose units, joined together by alpha or beta glycosidic bonds. A condensation reaction can occur when more than two monosaccharides are joined together to produce a polysaccharide, and as a result of this a water molecule is formed. However, adding water or acid can reverse this reaction, this is known as hydrolysis. The most common sugar found in polysaccharides is glucose. The diagram above shows two monosaccharides joining together to form a disaccharide, and this process is the same for polysaccharides. The three main examples of polysaccharides are starch, glycogen and cellulose. Starch Starch is made up of amylose and amylopectin. Amylose, is made up of several thousand glucose residues, which are attached by alpha 1,4 - glycosidic bonds. However, amylopectin consists mainly of alpha 1,4 - glycosidic bonds but it additionally contains alpha 1,6 - glycosidic bonds because it is a branched compound. Plants produce sugar by converting carbon dioxide and water via photosynthesis. However, when an excess amount of glucose is produced the rest is stored as starch. The plant usually uses the stored starch to use at night when it is unable to photosynthesise because of the
