Biology Revision notes - Human Biology
Blood Pressure * Each time your heart contracts, it pumps blood into out arteries. * The blood needs to be under pressure so that it reaches all the parts of the body. A pulse - this is the recoiling of the arteries. Arteries are elasticised so that when blood is pumped, they expand and then contract. * The fitter you are, the lower your heart rate is because your heart is more efficient. * Pressure is created due to the blood pressing against the arteries and this is known as blood pressure. Blood pressure appears as a fraction and is measures in mmHg: Systolic: the heart contracts and pumps - The highest pressure on the arteries. Diastolic: the heart is relaxes and doesn't pump - The lowest pressure on the arteries. (mmHg - millimetres/mercury) Blood pressure is affected by: * Weight - being overweight increases the risk of high blood pressure * Exercise - strengthens heart muscles and keeps the heart fit * Diet - avoid salty and fatty foods * Temperature * Alcohol * Stress * Smoking - narrows blood vessels * Inheritance * Age - blood pressure increases with age * Underlying diseases High Blood Pressure Can cause: * An artery to burst * A stroke * A heart attack * Death High blood pressure means that the blood is pushing too hard against the artery walls. This damages the artery lining and allows fat and calcium to build up and form a plaque.
Resistance Aim: my main aim is to investigate the factors that affect the resistance in a conductor, in which here I am using a nichrome wire.
What factors affect the resistance of wire? Aim: my main aim is to investigate the factors that affect the resistance in a conductor, in which here I am using a nichrome wire. The focal factors that affect the resistance in a conductor are: * Length * Temperature * Cross- section area * Material Hypothesis: I think that the more the cross-section area, the lower the resistance in the conductor or the nichrome wire will be. This is because the resistance happen due to the movement of the electrons through the material ( once a voltage has been applied ) they collide with the atoms in the material and as a result lose some of their energy. The idea of resistance is simply how difficult it is for the electrons to move through a material. The more difficult it is, the more energy they lose in the material on their movements. The definition of an electrical resistance is the ratio of voltage to current. The equation we use to find the resistance from the current and voltage is: Resistance (R) = Voltage (V) / Current (I) To put it in a simpler way, it is the number of volts difference across the object when one amp of current flows. It should be remembered that voltage is the number of joules of energy transferred by one coulomb of charge, and that current is the number of coulombs of charge passing a place each second. Now what the object is made of this means its
Investigating the effect of Sucrose Concentration on the Rate of Osmosis in Potato Chips.
G.C.S.E Science: Investigating the effect of Sucrose Concentration on the Rate of Osmosis in Potato Chips Sophie Chapman 25th March 2003 Aim: I shall carry out a sequence of independent experiments in order to investigate how the rate of osmosis in a potato chip is affected when the concentration of sucrose solution is varied. Apparatus: 300ml Sucrose concentration 300ml Distilled Water 2 x 100ml beaker 1 x 100ml Measuring Cylinder 1 x Potatoes 1 x Forceps (Tweezers) 1 x Scalpel Chipper 12 x Polystyrene Cups 1 x Stop - clock Tissues 12 x Sticky Labels 1 x Pen 1 x Calculator 1 x Ruler (measuring mm) 1 x Balance 1 x Polythene Food Bag Cardboard Apparatus Justification: To complete the experiment, I need 300ml distilled water and 300ml sucrose concentration as I intend to carry out 12 tests (using 6 different volumes but each shall be repeated twice) each using a 100ml of liquid whether it be pure water, pure sucrose concentration or a solution containing both. I will detail about the exact volumes of water and sucrose concentration that I want to use in each experiment, in the written procedure. I shall use varied amounts of sucrose solution for each test in order to adjust the concentration - a solution containing more sucrose has a greater concentration than a solution containing less sucrose solution. It is essential that the concentrations be
An investigation into the effect of a germination inhibitor on the germination of seeds.
GERMINATION INHIBITORS An investigation into the effect of a germination inhibitor on the germination of seeds. INTRODUCTION The necessary conditions For a seed to germinate there are specific conditions different seeds need. In this experiment, cress seeds are to be used. Going through the basics first though, for a seed to successfully germinate there needs to be: o An adequate supply of water o A suitable temperature o An appropriate partial pressure of oxygen o A suitable supply of light Water uptake is a crucial part of the necessary conditions because germination can only commence after the uptake of water by the seed. Water absorption is imbibition. The optimum temperature for germination is the optimum for the enzymes involved in mobilisation of food reserves, provided that other factors are not limiting. This temperature varies from species to species (i.e. 1 - 45°C). Respiration makes available the energy for metabolism and growth. Germinating seeds respire very rapidly, and require oxygen for aerobic respiration. Seeds will not germinate in the total absence of oxygen. Diffusion of oxygen through the testa may be slow, however, and in the early stages of germination seeds may rely on some anaerobic respiration, at least until the testa has ruptured. So this explains why water, oxygen and a suitable temperature are needed for germination, therefore
To investigate how varying the concentration of sucrose solutions affects the rate of osmosis between the solution and potato cylinders immersed in it.
Osmosis in potato cells Section 1: Planning Aim: To investigate how varying the concentration of sucrose solutions affects the rate of osmosis between the solution and potato cylinders immersed in it. Hypothesis: A substance, when dissolved in water, has a natural desire to dilute itself by bonding with surrounding water molecules. When a semi permeable membrane, such as a cell membrane separates two solutions, pure water flows from the weaker solution to dilute the stronger one until they are both the same strength. The term used to describe the flow of water through a semi permeable membrane separating two solutions of different concentrations is osmosis. In other words, osmosis is the process in which water passes in and out of plant cells thus controlling their turgidity. It is in fact the diffusion of water from places of high water concentration to places of low water concentration and can take place only across a selectively permeable membrane - such as the cell membrane. The cell membrane allows small molecules such as those of water to diffuse through it. However, larger molecules such as those of sucrose can not pass through its pores. This movement of water will continue until equilibrium is attained and the concentration is equal on both sides of the cell membrane. An example of a region with high water concentration is distilled water or very dilute
Gene Therapy And Gene Technology
Gene Therapy & Genetic Engineering What Is Gene Therapy? In recent years there have been truly great discoveries and advances in medical science. One of these discoveries is the idea of Gene Therapy. The concept of Gene Therapy was presented in the late 1970's. Scientists believe that a gene can be transplanted into humans who suffer from severe diseases that are life threatening. Gene Therapy can be defined as "the use of genetic material (usually deoxyribonucleic acid - DNA) to manipulate a patient's cells for the treatment of an inherited or acquired disease."Gene Therapy might seem a simple procedure; however it is a very complicated medical treatment. It is quite remarkable how Gene Therapy can be used to treat diseases and disorders by modifying a person's genome as it is impossible to change the genes in every cell. However, scientists have said that by targeting specific areas, it is possible to provide some sort of treatment or cure. In strong support of the idea, medical scientists say gene transplants could perhaps even cure diseases for which no effective treatment exists. Gene Therapy seems to be an excellent method to cure severe diseases and disorders and keep people healthy. However there is speculated side effects which are possible and that scientists are currently working on to improve. On top of this, there are many limitations on this therapy such as
An investigation into the abundance of fresh water black fly larvae, Simuliidae, between pools and riffles in Woodford meanders on the 19th September 2003.
An investigation into the abundance of fresh water black fly larvae, Simuliidae, between pools and riffles in Woodford meanders on the 19th September 2003. Abstract:- My investigation was to see where the black fly larvae, Simuliidae, preferred to inhabit, slower moving pools or fast moving riffles. I accomplished my results on the 19/09/03 at Woodford meanders using a "stone shake" sampling method. The results were conducted on the same day and within 3 hours from the first to the last. Readings of temperature, width, depth and impellor travel time were taken at each sample point. I plotted a graph of, pools or riffles against number of black fly larvae, Simuliidae. To analyse my results I used a Mann Whitney U significance test which showed with a 5% significance that the black fly larvae, Simuliidae, preferred the faster moving riffles or the slow moving pools. Introduction:- I accomplished my investigation at Woodford meanders (Grid reference - Sr06370638) on the 19th of September 2003. I chose to investigate the abundance of the black fly larvae, Simuliidae, whether they are in higher concentration in the slow moving pools or the fast moving riffles. I chose a freshwater dwelling species because there was a stream, Woodford meanders near to the base camp, Nettlecombe court, where we were staying, therefore it was more accessible, there was no time limit and in case of
Enthalpy of Neutralisation.
TITLE: Enthalpy of Neutralisation. AIM AND HYPOTHESIS: My aim in this experiment is to compare the enthalpy change of neutralisation by titration, for each reaction between the following 3 acids: Sodium hydroxide (NaOH) and hydrochloric acid (HCl) - pH 1 Sulphuric acid (H2SO4) and NaOH - pH 1 NaOH and Ethanoic acid (CH3COOH) - pH 2.88 - 3 I predict the reaction between the above-mentioned acids would be exothermic because heat will be given off during the reactions and the temperatures will be rising due to the heat evolved. I also predict the reaction between the chemicals is exothermic because the energy content of the products is less than that of the reactants, resulting to heat being given out from the system. These predictions show that the stronger the acid used in neutralization, the more energy is released per mole of water. I will be able to compare these predicted energy changes with my actual results after my experiment. When I have my results- the temperature change from beginning to end of the experiment - I can use the equation Energy change = mass of solution x temperature change x specific heat capacity of water to work out the actual energy change. In neutralization, we assume that the density of the acid/alkali is the same as that of water, so volume of acid = mass of acid. We know that the specific heat capacity of water is always 4.2 Jk - 1 g
AN INVESTIGATION OF THE DIFFERENT SPECIES OF MAYFLY WITHIN THE POOL & RIFFLE
AN INVESTIGATION OF THE DIFFERENT SPECIES OF MAYFLY WITHIN THE POOL & RIFFLE AIM: I am going to investigate the different species of Mayfly within the pool and riffle. I am going to create tables to show results from my investigation. I am also going to draw graphs to show the distribution of Mayfly Nymphs within the pools & riffles. NULL HYPOTHESIS: There is no significant difference in numbers of Mayfly Nymphs found within the riffles and pools. ALTERNATE HYPOTHESIS: There is a significant difference in numbers of Mayfly Nymphs found in the riffles and pools. STREAM: Data was collected from Nant Iago (James Stream) which is situated in St Mary's Vale. It is surrounded by Beech woodland. The source of the stream is the Sugar Loaf Mountain. It also contains peaty soils that are slightly acidic. Many erosive streams receive most of their energy from organic matter washed into the stream, largely as leaf litter. The litter is processed to carbon dioxide by a succession of microrganisms and animals, which deal with successively smaller particles of it in a continuous sequence, as it is moved downstream. This is common where the stream is bordered by gallery forest A flowing freshwater stream is all business. It rushes forward. If it slows at all, it is just to create small whirlpools or eddies and then it's back on down the mountain. It makes its bed on gravel or hard
An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice:
An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice: Introduction: Woodlice are one of the easiest terrestrial arthropods to obtain in large numbers throughout the year. Porcellio scaber, the most common species is not difficult to identify with the naked eye, and is large enough to be handled without employing special techniques. Their behaviour is relatively simple yet providing perfect examples of kinesis and taxis. i A species, which shows taxis, can orient the direction of their movement with respect to the source of an external stimulus whilst kinesis is a steady-state dependence of the movement velocity on the stimulus intensity.iii Thus it is clear that kinesis will be the important response in my investigation as I am not concerned with the stimulus direction. Woodlice lack a waxy cuticle on their exoskeleton and have a high surface area to volume ratio. This means that they are prone to desiccation. As a result, much of their behaviour is concerned with reducing water loss. Woodlice will therefore tend to congregate in more humid, cooler and darker regions where their water loss will be lower.ii Although light does not affect the physiological state of woodlice in the same way as humidity and temperature, it plays a very important part in woodlice behaviour. Woodlice have a negative photokinesis- they move faster as
