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Biology revision AP2 - Coggle Diagram
Biology revision AP2
cell biology
Transport in cells
osmosis
movement of water particles from an area of high concentration to an area of low concentration across a partially permeable membrane.
required practical: Investigate the effect of a range of concentrations of or sugar solutions on the mass of plant tissue
variables
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control (what's the same): the temperature, the length of time the cylinders were left in the solution and the volume of the solution
Evaluation
Before the mass of the cylinders is measured again, they should be rolled on tissue paper to remove any excess solution
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If the cylinders change in mass, they have gained or lost water by osmosis
Method:
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- Place the cylinders in different concentrations of sugar solution
- After about 30 mins remove the cylinders and measure their mass again.
diffusion
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example of diffusion
Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney.
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active transport
movement of particles from an area of low concentration to an area of high concentration against the concentration gradient. process requires energy.
In plants
allows mineral ions to be absorbed from the soil into the plant roots. this is because there is a low concentration of mineral ions in the soil and a high concentration inside the plant, active transport occurs which allows the plant (roots) t draw out more and more mineral ions from the soil.
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In animals/humans
there is a lower concentration of sugar molecules in the gut, and high concentration in the blood, and therefore active transport allows sugar molecules to be absorbed from the gut into the blood. These sugar molecules are then used for cell respiration
Exchange surfaces
Villi
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villi increases the surface area so that digested food is absorbed much more quickly into the blood.
Fish gills
water goes in through the fish's mouth and then O2 diffuses from the water into the blood in the gills where CO2 diffuses from the blood into the water.
gill filaments-provide a large surface area which increases the rate of diffusion more gas exchange can happen at once.
lamellae-tiny structures which increases the surface area even more. these structures are covered with many blood capillaries to speed up diffusion.
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blood flows through in one direction and water in the opposite direction which maintains a large concentration gradient. concentration of oxygen in water is always higher than that in the blood, so as much oxygen as possible diffuses from the water into the blood.
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Infection and response
monoclonal antibodies
an antibody is a protein that is produced by white blood cells. They have a specific shape that are able to bind to a specific antigen on a pathogen.
steps involved
- inject preferred lab animal with a specific pathogen which will result in an immune response and the production of a specific antibody.
- immune response leads to the production of antibodies by lymphocytes. these will be collected from the animal
- obtain a melanoma cell ( cancerous cell) an fuse it with the antibodies that were collected. a hybridoma cell is created
- hybridoma cells are cloned to produce multiple copies of the antibodies required.
- isolate/collect the monoclonal antibodies for use.
uses
cancer treatment.
Cancerous cells have antigens on their surface. Monoclonal antibodies can be designed to bind specifically with these antigens. When injected into a person's body, the monoclonal antibodies will bind with these cancer cells and clump them together. this makes it easier to identify a cancerous tumor, which can then be treated or removed. A radioactive substance may be attached to these antibodies so that it is easier to detect the tumor e.g., using a PET scan.
pregnancy tests
pregnancy test kits also use monoclonal antibodies. these have been designed to bind with a hormone called HCG, which is found in the urine of pregnant women. Monoclonal antibodies are attached to the end of a pregnancy test stick onto which a woman urinates. is she is pregnant, HCG will be present in her urine and will bind to the monoclonal antibody on the pregnancy stick. This will cause a change in colour or pattern which will indicate pregnancy
advantages/disadvantages
cheaper to develop that other drugs.
side effects on humans are reduced due to animal testing and produces human hybrid cells
Monoclonal antibodies create more side effects than expected. They are not yet as widely used as everyone hoped when they were first developed. it can have many side effects. it can be difficult to produce the correct antibody.
clinical trials
stages involved
1) Drug discovery: identification of a possible drug. testing on isolated cells-many drugs fail here.
2) Preclinical trials: Animal testing (might cause ethical issues)- to see effects on a living organism.
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5) phase 3-clinical trials: if safe and effective, bigger clinical trials begin. aim to find optimal dose.
6) phase 4-clinical trials and beyond: medicine undergoes legal testing. if passed, can be prescribed by doctors. safety monitored for as long as in use.
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Bioenergetics
Photosynthesis
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produces glucose
uses of glucose.
Releases energy in respiration -Store as starch - glucose converted back when needed e.g. in winter or at night. Starch is insoluble
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used to produce amino acids-used for protein synthesis. to produce proteins, glucose is combined with nitrate ions (absorbed from the soil).
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required practical
1) Start by taking a boiling tube and placing it 10cm away from an LED light source. (Don't release much heat)
2) Fill the boiling tube with sodium hydrogen carbonate solution. (Releases carbon dioxide- needed from photosynthesis).
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9) Do the whole experiment again from 20cm, 30cm and 40cm.
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