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Photosynthesis - Absorption spectrum.

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Photosynthesis light Water + carbon dioxide � glucose + oxygen 6H2O + 6CO2 � 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 6H2O�12H + 3O2 Light splits water into hydrogen ions and oxygen. 2) The dark reaction enzymes 12H + 6CO2 � 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. ...read more.


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. ...read more.


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 � carrier transports substance across membrane using energy from ATP � 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 Biology Notes ...read more.

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