What are the advantages of an electron microscope?
• Higher resolution • Higher magnification
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Total magnification
Eye Piece Lens x Objective Lens
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What is resolution?
The ability to distinguish between two points
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What is cell differentiation?
The process by a cell changes to become specialised for its job.
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How does surface area affect diffusion?
The larger the surface area of the membrane, the faster the diffusion rate because more particles can pass through at once.
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How are villi adapted for their purpose?
• The small intestine is full of lots of mitochondria • They have a large surface area • A single layer of surface cells • Good blood supply to assist quick absorption
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How are the gills adapted for gas exchange?
They have a large surface area. Each gill is made up of lots of thin plates called gill filaments which allow for a big surface area of gas exchange. There is also a thin surface layer of cells to minimise the distance that the gases have to diffuse.
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How do fish use gas exchange?
Water enters through the mouth, as this happens oxygen diffuses into the blood and carbon dioxide diffuses into the water. Blood flows in one direction and water flows in the opposite which maintains a large concentration gradient.
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What is a catalyst?
A substance which increases the speed of a reaction without being changed or used up in the reaction.
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How does light intensity affect transpiration rate?
The brighter the light, the greater the transpiration rate. Stomata begin to close as it gets darker, when photosynthesis can’t happen. When the stomata are closed, very little water can escape.
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How does temperature affect transpiration rate?
The warmer it is, the faster the transpiration rate because particles have more energy to evaporate and diffuse out of the stomata.
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How does air flow affect transpiration rate?
The better the air flow, the greater the transpiration rate. If the air flow is poor the water vapour surrounds the leaf and doesn’t move away meaning there is a high concentration of water so the rate decreases.
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How does humidity affect transpiration rate?
The drier the air around a leaf, the faster the rate of transpiration. Diffusion happens fastest when there’s a really high concentration in one place and a low concentration in the other.
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What is respiration?
The process of transferring energy from glucose which goes on in every cell.
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What is metabolism?
The sum of all the reactions that happen in a cell or the body
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Treatment for CHD: Stents
Keep the arteries open
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Treatment for CHD: Statins
Reduce blood cholesterol levels and lows down the rate at which fatty materials build up.
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How can metals be extracted with carbon?
In this reaction the ore is reduced; the position of the metal H2SO4in the reactivity series determines whether it can be extracted by reduction with carbon.
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Process of separation: Chromatography
Used to separate dyes in an ink. Some compounds dissolve well in water but sometimes other solvents like ethanol are needed.
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Process of separation: Filtration
Separates insoluble solids from liquids. It can be used in purification.
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Process of separation: Evaporation
Involves slowly heating a solution where the solvent evaporates. Eventually crystals start to form.
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Process of separation: Crystallisation
Pour the solution into an evaporating dish, the solvent will evaporate and once you see crystals begin to form remove from the Bunsen. Filter the crystals and leave them in a warm place to dry.
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Process of separation: Distillation
Used to separate out solutions. The solution is heated and the substance with the lowest boiling point evaporates first – the vapour is cooled and condenses and before being collected. The rest is left in the flask.
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