The Absorption Spectrum of Chlorophyll

The Absorption Spectrum of Chlorophyll
Water + carbon dioxide â?? glucose + oxygen 6H2O + 6CO2 â?? C6H12O6 + 6O2 Absorption Spectrum An absorption spectrum shows which wavelength of light a molecule absorbs. Action Spectrum An action spectrum shows the effect of each wavelength of light on the rate of photosynthesis The absorption spectrum of chlorophyll is very similar to the action spectrum of photosynthesis. This is evidence that chlorophyll absorbs light for photosynthesis. The Light and Dark Reaction 1) The light reaction light 6H2Oâ??12H + 3O2 Light splits water into hydrogen ions and oxygen. 2) The dark reaction enzymes 12H + 6CO2 â?? C6H12O6 + 3O2 Glucose is then formed from the hydrogen ions and carbon dioxide. (This reaction does not occur in the dark). Factors affecting the rate of photosynthesis The Light Reaction Chlorophyll can split more water molecules at higher light intensities. Photosynthesis will reach a maximum rate when chlorophyll is saturated by sunlight. The Dark Reaction An increase in temperature will increase the rate of glucose production until it reaches the optimum temperature for the enzymes. The enzymes will be denatured if it goes above a certain temperature. An increase in carbon dioxide will also increase the rate of glucose production. Millions of years ago there was much more carbon dioxide in the atmosphere, the plants sucked up the carbon dioxide and pumped out oxygen, this gave the atmosphere we have today. These factors depend on each other.
They must all be at their optimal amount for photosynthesis to occur at a maximum rate. The factor that restricts the effect of the others is known as the ?limiting factor?. Use of glucose from photosynthesis Respiration Energy is released from glucose and used for growth and repair. Storage Glucose is stored as starch. Starch is insoluble and so doesn?t change the osmotic potential of the cell. Starch is made of long chains of glucose molecules. It can be broken down when glucose is needed. Transport Glucose is turned into sucrose for transport in the phloem around the plant. Synthesis of other substances Chains of glucose molecules form cellulose for cell walls. Glucose + nitrates and sulphates from proteins. Glucose + phosphate forms dna. Glucose + magnesium forms chlorophyll. Mineral Nutrition in Plants Plants need water, carbon dioxide and light. They also need many minerals: Â? Nitrates ? nitrogen is needed for proteins, leaf and stem growth Â? Phosphates ? phosphorous is needed for respiration, photosynthesis, healthy roots and dna Â? Potassium ? needed for leaf and flower growth Â? Magnesium ? needed for chlorophyll The plants absorb water and dissolved minerals through the roots. The water and the dissolved minerals are transported in the xylem to the stem and leaves. This is called the transpiration stream. Mineral Deficiency Symptoms Â? Nitrogen deficiency ? weak stem, stunted growth, yellow leaves. This is because due to no sunlight being trapped since there?s no chlorophyll. Â? Phosphate deficiency ? stunted growth, poor root growth, purple leaves. This is because of poor root growth so less photosynthesis because of less water and minerals being sucked up. Â? Potassium deficiency ? yellow leaves, poor fruit and flower growth. Since it has yellow leaves, this means there?s no chlorophyll to trap sunlight so less photosynthesis takes place. Â? Magnesium deficiency ? yellow leaves, stunted growth. Same as above. Digestion Definition Digestion is the breakdown of large, insoluble food molecules into small, soluble molecules so that they can be absorbed into the bloodstream. Effect of temperature on Enzymes Boiling the liver denatured the catalyst. This means that the catalyse does not work. This happens because the linkages in its molecules break down this is due to the high temperature. As the temperature goes up, so does the rate of reaction for the enzyme, but once it has gone past its optimum temperature the rate of reaction drops rapidly, and the enzyme will become denatured. Teeth and Feeding Â? Enamel ? covers the exposed part of the tooth and makes a hard biting surface. Â? Dentine ? it is like bone, and it is softer than the enamel, calcium helps to strengthen it. Â? Pulp ? this is the centre of the tooth, it is a soft connective tissue, it contains cells, which make the dentine and keep the tooth alive. Â? Cement ? it is a bone like substance, which covers the roof of the tooth. Â? Incisors ? used to cut pieces off the food Â? Canines ? used similarly to incisors Â? Premolars ? used to crush food to small pieces Â? Molars ? same as premolars Adaptation of teeth and skull to diet Diets Carnivore Protein rich meals, long intervals between meals, teeth used to catch prey as well as physical digestion. Herbivore Food is poor in nutrients, large quantities of food eaten frequently, mostly cellulose that is difficult to digest, food is ?harvested? and not caught. Carnivores Incisors ? Theses are pointed, and is able to apply more pressure, which means it is easier to cut off food, the incisors in the bottom jaw are like a more chiselled shape, and is there to pierce. Incisors are there to meet and grip the prey and to tear flesh away from near the bone. Canines ? The canines are long, curved and very sharp, they are there to hold and kill the prey. They can exert a lot of pressure to pierce the skin; also can be used as weapons when fighting for a mate. Per/molars ? The 1st molar on the lower jaw and the last premolar on the upper jaw are called the carnassials teeth. These teeth slide past each other like scissors, they pass and cut flesh and crack bones. They shear flesh from the prey. The other teeth are flattened and have sharp edges for cutting flesh and cracking bones. A Carnivore?s teeth are adapted very well since they only eat flesh, which means they eat other animals. The incisors are there to cut the flesh off the animal and to keep the prey from moving too much. The canines are there to grip and kill the prey, these are adapted very well, and since they are sharp so it can pierce the prey?s skin very easily. The molars and premolars are there to crush bones and chew the flesh even further; these are very well adapted since the top teeth would fit nicely into the bottom ones, making the chewing processes a lot of efficient. Carnassials teeth are adapted very well, since they fit together like scissors, they can crush bones and cut off pieces of flesh a lot easier. The joint between the lower and upper jaws are close fitting allowing only up and down movement. This also makes it hard to dislocate when struggling with prey. Large temporal muscle provides force to cut flesh and break bones. The temporal muscle is attached to the ridge on the top of the skull. Eyes are set in the skull facing forward; this is so they can judge the distance between them and their prey, so they can decide when to pounce. Carnivores have a very small masseter muscle since they do not use it very often. Carnivores also have a thick skull; this is to protect itself when catching prey or when fighting for mates. Herbivores: Incisors and canines ? there are only incisors and canines in the lower jaw; these teeth are used to cut through plants. They are similar in size and shape. Lower teeth act as blades cutting upwards against the horny pad (cropping). Pre/molars ? these teeth slide other each other and grind the food. They have a broad surface for grinding. The upper teeth have a W shape, and the bottom teeth have an M shape, so they fit together nicely, and can grind the food more efficiently. Enamel has worn away in the troughs leaving hard enamel ridges. But fortunately for the herbivores, the enamel always grows back, but there would never be any enamel at the top of the tooth. The teeth of the herbivore are very well adapted, the incisors and the canines are like little blades, and these are adapted very well since they can crop plants more efficiently. They don?t really have a need for canines, this means that they have become more and more like incisors. The molars and premolars are very well adapted as well, since they have a broader area for grinding the leaves and the shapes of the teeth fit nicely as well, meaning that it can grind more efficiently. [image]Unlike the jaws of a carnivore, the jaws fit loosely, so this means that they can move side to side as well as up and down, allowing better grinding movements. The temporal muscles are small, but the masseter muscles are large, which is the opposite of a carnivore. They mainly rely on the masseter muscle to move their jaw. They have no ridge on the top of the skull, because the temporal muscle is small. Their eyes are on the side of their head, which means that they can see predators coming from almost any direction, which is a good thing, since they can hardly protect themselves. They have a toothless gap called the diastema; this is there so they can separate the freshly cropped foods, from the already chewed food. The horny pad is there so the teeth can crop food better, because the top is like a cutting board, and the teeth are like knives, it gives something for the ?knives? to push against. Digestion in Herbivores ?Sucking Herbivores Some ?sucking? herbivores developed their mouthparts to either: Â? Suck nectar from flower e.g. butterfly Â? Pierce plants and suck out the cell sap e.g. aphid The cell sap and nectar is mainly sucrose. This is easy to digest. ?Cropping? Herbivores Most herbivores have mouthparts that cut and eat fragments of plant tissue. 50% of plant tissue is made of cellulose. Cellulose is made of long chains of glucose: [image] Each chain can contain 10000 glucose molecules. The chains lie side by side and form chemical bonds with each other. [image] Lots of chains bond together to form bundles. Theses bundles are very strong. The bonds make cellulose very difficult to digest. Cellulase can digest cellulose but bacteria only make this. Ruminants Ruminants include cows, sheep, goats, antelopes, gazelles, deer and giraffes. They all have a stomach with four chambers. They are able to regurgitate, or bring food back to their mouths after swallowing it, in order to chew the food further ? a process called rumination. Ruminants can eat quickly; store masses of food in their stomachs, then retire to a place secure from predators to finish chewing in safety. 1) Rumen ? This is home to billions of microbes, which can eat grass and hay. These bacteria, for example, fungi provide nutrients that the cow can digest. Without these microbes, the cow would die. Rumen microbes help the cow eat hay, which is made of cellulose and other polymers, which are long molecules that the animal cannot digest, but microbes can. The microbes break down the cellulose into smaller bits, which the cow can take in, or absorb. The microbes use special proteins called enzymes to break down cellulose into small bits. 2) Reticulum ? This is a membrane with ?honeycombed? ridges; these ridges break the food down into smaller pieces. Have many of the bacteria that are in the rumen. Then the cow regurgitates those pieces of broken food so it can chew it again. 3) Omasum ? This is the third stomach. During this process, the food breaks down into vitamins and nutrients that the cow?s body absorbs to meet its daily nutritional needs. This part has a capacity of about 10 litres. The omasum is a small organ with great absorption capacity. It allows the recycling of water and minerals such as sodium and phosphorus, which return to the rumen through the saliva. Since the modes of digestion in the rumen and the abomasum differ drastically, the omasum acts as an organ of transition between these two organs. The omasum is not essential, however, as it is absent in camels, llamas and alpacas (pseudoruminants). 4) Abomasum (true stomach) ? This is the fourth stomach of a cow?s digestive system. The final digestive processes takes part here, in the abomasum the cow?s system gets all the remaining good value it need from the food before letting it pass into the intestines. This stomach is like the stomach of non-ruminants. It secretes a strong acid and many digestive enzymes. In non-ruminants, ingested feeds are first digested in the abomasum. However, the material entering the abomasum of a ruminant is made up primarily of unfermented feed particles, some end products of microbial fermentation and microbes, which grew in the rumen. Rabbits Â? The caecum is larger than the stomach because it is in these organs that the digestion of plant cell walls takes place, largely as a results of bacterial activity, and since a lot of a rabbit?s diet is grass, this grass must be digested in the caecum since it cannot be digested in the stomach, this is why a rabbits caecum is bigger than its stomach. Â? Rabbits do not chew the cud because food is regurgitated from the second stomach, and since rabbits only have one stomach, it is impossible for them to chew the cud. Â? Rabbits have evolved to feed on poor quality grass that are low in nutrients and high in fibre because this is a lot of grass hence less competition for food. They need grass with a lot of fibre so it can clean out their intestines so they can eat their faeces. They eat grass with little nutrients so they can digest it easier. Â? Molars and premolars grind up the grass and these teeth will constantly grow because the fibre that rabbits chew are always wearing down the teeth. Â? If you feed rabbits muesli, they will only eat the bits they like and the food was made so that the whole diet was balanced, so when the rabbits start leaving bits, it unbalances their diet. Hay is the perfect foodstuff for rabbits because hay can contain fibre, calcium and protein, and it is also good because it is just long, dried grass, and grass has a lot of the things rabbits need, like fibre. Â? If a rabbits diet lacks fibre, then it means that the rabbit cannot constantly grind its teeth on the fibrous material, this means the teeth will carry on growing, resulting in overgrown teeth, and these affected teeth will rotate in the sockets, causing the upper and lower teeth to be no longer aligned. Sharp spikes will then form on the teeth and it cuts the tongue and cheek. Â? A type of faeces called caecotrophs is done by bacterial fermentation in the caecum. This caecal fermentation produces volatile fatty acids and material rich in amino acids and vitamins. Amino acids produce protein and since rabbits do not eat meat, the need to eat this bacteria in order to get protein. Mussels Â? The mussel has 4 large gills, they are covered with small cilia, and the beating of the cilia draws a current of water in between the two pairs of gills and between the shells and forces it through the gills. Â? The water originally came in through the opening fringed with ?tentacles? and goes out of the smooth edged opening. If anything touches the tentacles, the mussel would close its shell at once Â? When water is being pushed through the gills, the gills would filter out any food particles and the filtered water is expelled through the exhalant siphon (gaseous exchange also happens like this). Â? The food particles are the pushed down the gills by the cilia moving like a Mexican wave. Â? The ridges of the gills excrete mucus, the food particles are trapped here, the palps pulls in the string of mucus and the mouth eats it. Insect Mouth Adaptations Aphid ? Has a sharp mouth able to pierce through stems. Lips formed to make protective mould for needle. Pierce needle into phloem and sucks up sucrose because it is easy to digest. Salivary gland has enzymes to digest sucrose. Pointed tough and inflexible stylet (proboscis end). Stylet is formed from long sharp mandibles and maxillae. Stylet pierces plant and reaches phloem. Cell sap is forced up the food canal in the stylet by the pressure in the phloem. Butterfly ? It has no mandibles. Maxillae fit together with food channel in the middle. The proboscis is curled up to save space and prevent from breaking. Uncurls and reaches into flower to the nectrees. Muscles in proboscis contract to unwind it. Muscles behind the mouth contract to suck nectar up. Housefly ? No mandibles or maxillae, proboscis is a modified lower ?lip?. Spongy pad at the base of the proboscis. Fly excretes enzymes onto food to digest it. Channels in the spongy pad soak up digested food. Channels lead to central food canal that sucks food up the proboscis. Blood is pumped into the proboscis to move it down onto the food. Mosquito ? Only the female mosquito feeds on blood. Lower lip forms sheath to protect proboscis. Upper lip forms a tube to suck blood. Mandibles and maxillae are long and sharp. They pierce the skin making a hole for the proboscis. Proboscis is inserted into a capillary and sucks up the blood. The mosquito secretes saliva into the capillary, which stops the blood clotting. Heart and Blood vessels Vena Cava and Aorta Aorta ? the function is to carry blood away from the heart and to the body. It has thick walls, retains shape, springy, like a pipe and it is white. The aorta has elastic tissue and muscle fibres in their thick walls, having thick walls makes it stronger, and having elastic tissue makes it more elastic and able to bear the constant pumps of blood and able to stand up to the surges of high pressure caused by the heart beat. Vena Cava ? the function is to carry blood to the heart, away from the body, it has thin walls, has a beige-brown colour and is collapsed. The vena cava is wide, but the walls are thinner, less elastic and less muscular than the aorta, this is because the blood pressure in them is steady and less than that in the aorta. Arteries ? fairly wide vessels that carry blood from the heart to the limbs and organs of the body. The blood in the arteries, except for the pulmonary arteries, is oxygenated. Veins ? returns blood from the tissues to the heart. They have valves in them. The blood is deoxygenated. It is wider but have thin walls. Capillaries ? tiny vessels, one cell thick, they transport blood by linking up arteries and veins. Systemic Circulation ? system of blood vessels that carries the blood to the body and back to the heart. Portal Vein ? blood vessel that carries blood between two sets of capillaries, e.g. hepatic portal vein. Pulmonary Circulation ? system of blood vessels that carries blood to the lungs and back to the heart. Artery Capillary Vein Endothelium Yes (smooth surface) Yes Yes Lumen Small Microscopic Large Thickness of walls Thick (muscle + elastic) 1 cell thick Thin Surface area Very small Big Small to v. Small Speed of Blood High speed/fast Very slow/slow Quite slow/slow Pressure of Blood High Quite low Very low [image]Advantage of double circulation Provides a vigorous supply of blood to the body because the heart pumps it a second time after it has lost pressure in the capillaries of the lungs. Red Blood Cells 5-6 million per mm³. Biconcave disc shape increases surface area for exchange of oxygen. No nucleus, which means more space for haemoglobin. Full of haemoglobin: Haemoglobin + oxygen â?? oxyhaemoglobin Plasma 90% water, dissolved nutrients. Dissolved waste (carbon dioxide and urea). Hormones. Plasma proteins (antibodies and fibrinogen (blood clotting) and others to maintain pH and water balance). White blood cells Defence against disease, 5000-10000 per mm³. Lymphocytes make antibodies. Phagocytes eat bacteria and viruses. It can move outside of blood between body cells and lymph fluid. Platelets Causes blood to clot, small fragments of cells made in bone marrow, no nucleus. Bacteria, Viruses and Fungi It was thought that microorganisms would appear and grown from certain non-living materials. This was known as spontaneous generation. Pasteur?s Swan Neck Flask Louise Pasteur (1860) showed that micro organisms are present in the air and do not spontaneously generate. Broth was sterilised by heating â?? sterile broth â?? spoiled broth with microorganisms Pasteur?s hypothesis was that microorganisms are in the air and they fall down the spout. Pasteur then demonstrated that sealing the flask after heating stopped any microorganisms from appearing: Sterile broth in sealed flask â?? No organisms appear But people said that this doesn?t prove anything because there isn?t enough vital spirits in the flask. Sterile broth in swan neck flask â?? Control: U turns traps dust and microorganisms; broth remains sterile Sterile broth in swan neck flask â?? Experimental breaking of swan neck provides access of microorganisms to flask, so broth spoils The swan neck flask remained sterile. Pasteur then tilted the flask and poured bacteria into the broth, and soon the broth was spoiled. comparision OF bacteria, fungi and bacteria ? see sheet Defence Against Disease Pathogen ? a disease-causing organism Antigen ? a protein found on the membrane of all cells, different cells have different proteins which have specific shapes. Microbe ? a microscopic organism Methods of infection ? food and water, touch (contagious disease), airborne (microbes in drops of mucus that are sneezed out of the body), animals (disease carriers are called vectors, e.g. mosquitoes with malaria), infected needles (e.g. aids and drug users), sexually transmitted. First Line of Defence Lungs ? Goblet cells secrete mucus. Mucus catches microbes and acts as a barrier. Stops microbes infecting epithelial cells. Cilia sweep the mucus and microbes out of the lungs. Eyes ? Tears contain antiseptic chemicals to kill microbes on the surface on the eye. Eyelashes catch big pieces of dirt and prevent it from entering the eye. Hair follicles ? Sebaceous glands secrete oil into the skin. It contains an antiseptic and is acidic. This kills some microbes. Stomach ? Glands make mucus to form a barrier. Hydrochloric acid in stomach kills microbes. Cuts ? Blood clotting seals cuts preventing microbes from entering the body. Skin ? Dead outer layer of skin cells forms a barrier. Dry to prevent microbes growing on its surface. PH of about 3-5 and this kills some microbes. Second Line of Defence Phagocytes ? 60-70% of all white blood cells, they ?eat? and infected and damaged cells. Natural Killer Cells ? 5% of all white blood cells, they release chemicals that kill infected cells by making them burst. Macrophages ? 5% of all white blood cells, they ?eat? cell debris and pathogens Third Line of defence ? this is an organised response that specifically attack the pathogen. It is carried out by the following white blood cells: 1) T helper cells (Dendritic cells) 2) T lymphocyte cells (T cells) 3) B lymphocyte cells (B cells) Treating Disease Blood Groups The ?abo? blood groups, red blood cells have two antigens called A and B. Blood Group Antigen Antibody A A Anti-B B B Anti-A AB A and B None O None Anti-A/B Donor?s Blood Recipients blood Blood Group Antibody made A B AB O A Anti-B √ x x √ B Anti-A x √ x √ AB None √ √ √ √ O Anti-A/B x x x √ AB is the universal recipient O is the universal donor If blood is transfused, the blood recognises a foreign antibody and thinks that it is a virus. It will then begin to attack the blood, and it will stick together so it is a solid and this would cause a blood clot. Immunisation Immunisation activates the primary response with out causing the disease. If that person the gets infected with the real disease the secondary response will destroy it before it causes any harm. The vaccine is either: 1) Dead pathogens 2) Inactive pathogens (attenuated) In both cases the antigen is present to trigger the immune system to make antibodies and memory cells. Injecting Antibodies Antibodies can be made and injected into a patient to simulate the secondary response and therefore cure a disease. This is called artificial passive immunity. The patient does not make any memory cells. The antibodies breakdown after a few weeks. There for the patient is not immune to the disease once he is cured. It is expensive and only used if the disease will be fatal before the patient?s own immune system can destroy it e.g. rabies, tetanus. Maternal Antibodies A mother will pass her antibodies to her foetus across her placenta. After birth she also gives her baby antibodies in her breast milk, especially in the first three days after birth. They protect the baby while its immune system develops. This is called natural passive immunity. The baby has no memory cells and therefore loses immunity when the antibodies breakdown. Antibiotics An antibiotic is a chemical produces by one microorganism that will kill or inhibit the growth of another microorganism. Other drugs will receive the symptoms of a disease but will not kill the pathogen e.g. painkillers. They kill bacteria by weakening their cell wall, which causes them to burst. It will not harm animal cells because they don?t have a cell wall. They are also useless against viruses, as they also don?t have a cell wall. Viruses are very difficult to kill using any drug without killing their host cell as well. Many diseases are becoming resistant to antibiotics. Bacteria can become resistant when a patient does not complete the full course of antibiotics. If some of the bacteria are not killed they can mutate to become resistant. Therefore we need to develop a wide range of different antibiotics and never overuse them. Antibodies Antibodies recognise pathogens because each antibody is designed to recognise a specific shape. Rather than recognising an entire molecule, antibodies bind to particular shapes on these target molecules. Breathing and Lungs Breathing This is also called Ventilation and it is not respiration. Breathing in = inhalation Breathing out = exhalation The purpose of breathing is to get oxygen into our body for respiration and to excrete carbon dioxide, a product of respiration. How we breathe: Â? When we inhale the diaphragm muscles contract and pulls it down, and the intercostals muscles contract and pull the ribcage upwards and outwards. Â? These two movements make the space in the thorax bigger, thus decreasing air pressure, so this forces the lungs to expand and draw air in through the nose and trachea. Â? When we exhale, the diaphragm muscles relax, allowing the diaphragm to return to its domed shape. Â? The intercostals muscles relax, allowing the ribs to move downward under their own weight and the pull of gravity. Â? The lungs are elastic and shrink back to their relaxed size (decrease in volume and an increase in air pressure) forcing the air out again. Â? The outside of the lungs and the inside of the thorax are lined with a smooth membrane called the pleural membrane. This produces a thin layer of liquid called pleural fluid which reduces friction between the lungs and the inside of the thorax, making it easier to breathe Â? It also holds the pleural membrane together. Â? The cartilage is there it make the outward movement of the ribs easier because its flexible. Gas Exchange at Alveoli 1) Large surface area ? more places for gaseous exchange 2) Rich blood supply ? more blood means more oxygen in blood 3) Thin walls ? makes gaseous exchange easier since the distance between the two isn?t as far 4) Moist layer on alveoli walls ? gases diffuse quicker in water. Oxygen and carbon dioxide are exchanged at the alveoli by diffusion. Diffusion is ?the movement of a substance from an area of high concentration to an area of low concentration?. Why Oxygen Moves Into Our Blood The oxygen moves from air to blood because there is a low concentration of oxygen in the capillary and there is a high concentration of oxygen in the air, this means the oxygen will diffuse from air to capillary. The carbon dioxide moves from blood to air because there is a high concentration of carbon dioxide in the capillaries and a low concentration of carbon dioxide in the air, so the carbon dioxide diffuses from capillary to the air. A diagram on the next page shows how this works. [image] Energy and Respiration Energy is the ?capacity to do work?; a cell will need energy for: 1) Physical movement e.g. muscles, heart, lungs, etc 2) Transport of substances by active transport 3) Synthesising new molecules e.g. growth and repair 4) Maintaining body temperature in warm blooded animals Aerobic Respiration Aerobic respiration uses oxygen to release energy from glucose. Glucose + oxygen â?? carbon dioxide + water + energy C6H12O6 + 6O2 â?? 6H2O + 6CO2 + energy/36ATP Energy released from glucose is ?trapped? in molecules of Adenosine triphosphate = atp Anaerobic Respiration Lots of oxygen available = aerobic respiration However, if oxygen is in short supply, or it cannot be supplied to meet demand for atp, then anaerobic respiration will take place: C6H12O6 â?? C3H6O3 + 2ATP Glucose â?? lactic acid + 2ATP atp ? the ?energy currency? of the cell Energy released from glucose is stored as chemical energy in atp. Any process in the cell can easily use this energy. atp (adenosine triphosphate) Energy from respiration â?? adp + Pi (adenosine diphosphate + phosphate) â?? Energy used be cell Lactic Acid and muscle fatigue Lactic acid builds up in the muscles, lowering the pH, this will: 1) Denature enzymes in respiration 2) ?Warp? muscle filaments so they cant contract causing pain = muscle fatigue Oxygen Debt After exercise you continue to breathe heavily. The body still has a high demand for oxygen: 1) Restore levels of atp by aerobic respiration 2) Lactate broken down by the liver into H2O and CO2 using oxygen Diffusion Definition ?The net movement of particles of a substance from a high concentration to a low concentration? Diffusion stops when concentrations become equal. The substance could be: Gas ? molecules Liquid ? molecules Dissolved solid ? ions Factors that affect the rate of diffusion Temperature ? increase in temperature means you increase kinetic energy, so they move about more Difference in concentration (concentration gradient) ? greater gradient is achieved by greater difference in concentration, which means bigger rate of diffusion, see it as a slope of a hill. Size of particle ? bigger particle means slower movement, which means slower rate of diffusion. In cells ? distance to diffuse across, surface area, volume ratio Surface area: Volume ratio ? The higher the ratio the quicker the diffusion into cell. Example of diffusion in biology 1) Gas exchange in alveoli ? short diffusion distance, high surface area, concentration gradient maintained by blood 2) Gas exchange in leaves ? short diffusion distance, high surface area (many stomata), concentration gradient maintained by photosynthesis, respiration and the wind. Osmosis Definition ?Osmosis is the net movement of water from a low solute concentration to a high solute concentration across a partially permeable membrane.? It is only the movement of water. The movement is random, in both directions, but it has an overall net movement. It has to be across a partially permeable membrane, which separate the two solutes. Water movement will stop when the solute concentration becomes equal. It doesn?t matter what solutes are dissolved in the water, but only depends on the difference in concentration. In Living Cells The cell membrane is partially permeable. Water will move in or out of a cell depending on the concentration of its surrounding solution. If the concentration of the solution is the same as the inside of the cell, it is said to be isotonic. Animal cell ? if concentration outside is higher, then water will move out and the cell will shrivel, but if it is lower, then water will move in and the cell will burst. Plants cell ? if the concentration outside is higher, then water will move out and the cell will plasmolysis (wilt), but if the concentration outside is lower, then water will move in and the cell will be healthy and turgid. Active Transport Definition ?Is the transport of a substance across a membrane from a low concentration to a high concentration of that substance.? Energy is required to move the substance against its concentration gradient because its natural tendency is to diffuse in the opposite direction. Substance combines with carrier molecule â?? carrier transports substance across membrane using energy from atp â?? substance released into cell atp provides the energy for the protein carriers to change shape and transport the molecules across the membrane. The rate of active transport will depend on the rate of respiration (production of atp). There fore it will be affected by oxygen availability, glucose concentrations and temperature. Examples of active transport are in the absorption of glucose in small intestine and the absorption of mineral ions by roots in plants. Ecology Ecosystem ? is made of a habitat and a community. Habitat -is the non-living part of the ecosystem. E.g. sea shore, desert, forest. Community ? is all the organisms that live in the community. Population ? is the number of individuals of the same species in that ecosystem. Adaptation An organism needs to be adapted to survive in its ecosystem. The organism will be affected by: 1) Abiotic (environmental) factors ? are due to the habitat, e.g. temperature, water, light, air, etc 2) Biotic factors -are due to the community, e.g. competition for food, water, light, space, etc

The Absorption Spectrum of Chlorophyll 7.9 of 10 on the basis of 2389 Review.