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# Unit 3 revision

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### Transcript of "Unit 3 revision"

1. 1. Unit 3 Revision<br />
2. 2. The effect of Caffeine of Heart Rate<br />
3. 3. Independent variable?<br />Temperature<br />Why it is important to use equal-sized cylinders of beetroot?<br />So that same amount of pigment will be present in each disc.<br />So that the number of cells in each disc can be controlled.<br />So that the surface area of the disc can be made uniform.<br />The Effect of Temperature on Membrane<br />
4. 4. The dependent variable?<br />Degree of redness<br />Describe how the degree of redness could be measured.<br />Shake the water in the boiling tube before measuring.<br />Select the blue filter in colorimeter<br />Keep an empty cuvette with wiped edges and make the reading zero.<br />Care should be taken to keep the transparent side of the cuvette facing the light or colorimeter.<br />Keep the cuvette with water from each repetition in the practical, inside the colorimeter holder.<br />Record absorbance from the colorimeter screen.<br />The Effect of Temperature on Membrane<br />
5. 5. Variables that need to be controlled<br />Volume of water in the boiling tube.<br />Uniform rinsing of beetroot discs.<br />Similar variety of beetroot must be used for the experiment.<br />The Effect of Temperature on Membrane<br />
6. 6. Antimicrobial Properties of Plants<br />Weigh 10g of the plant material to be tested for antimicrobial properties.<br />Grind the plant material in a pestle and mortar with 10ml of ethanol as the medium.<br />Collect the plant extract in a test tube.<br />Take 1ml of the extract into a cavity slide.<br />Prepare paper discs of 1cm diameter from filter paper.<br />Place these filter paper with a sterilised forceps into the extract in cavity slide.<br />Take 1ml of ethanol alone in another cavity slide.<br />Place another disc of the same diameter in this slide.<br />This will act as the control.<br />
7. 7. Antimicrobial Properties of Plants<br />Prepare agar medium in a Petri dish.<br />Pour a drop of bacterial culture on top of the agar medium.<br />Spread the bacteria all over the medium using a sterilized spreader.<br />Put the paper discs from plant extract and the control disc into the agar medium.<br />Place them well apart and cover the petri dish and close the lid with transparent tape.<br />Keep the petri dish upside down and incubate in an incubator for 24 hours at 24O C.<br />After incubation, observe clear areas around the discs.<br />If the plant is having antimicrobial properties, the clear area around the disc will be larger.<br />
8. 8. Sterilizing methods.<br />Disinfectants can be used to sterilize the area where the practical is being done.<br />Autoclave is used to sterilize the equipments used in the practical.<br />Flaming the forceps and glass apparatus before and after transferring bacteria is another aseptic method.<br />Antimicrobial Properties of Plants<br />
9. 9. Measuring the clear area around disc.<br />Keep a graph paper over the petri dish and trace the clear area on the graph paper.<br />Count the number of squares in the traced area.<br />Calculate the area of the trace from this.<br />Subtract the area of the disc from this value.<br />The result will show the size of the clear zone around the disc.<br />Antimicrobial Properties of Plants<br />
10. 10. Variables that need to be controlled<br />Temperature<br />pH<br />Volume of enzyme<br />Enzyme Concentration and Rate of Reaction<br />
11. 11. Independent variable?<br />the deficient mineral solution<br />Why it was important to make sure all the seeds were about the same mass?<br />To make valid comparison between seeds later.<br />Any differences between seedling masses later should be caused by treatment and not by their differences in the beginning.<br />Investigating Plant Mineral Deficiencies<br />
12. 12. Variables that need to be controlled<br />Light intensity<br />temperature<br />wavelength of light<br />carbon dioxide level<br />humidity<br />wind speed<br />Variety of seed or age of seed<br />pH<br />Same concentration and volume of other nutrients in the solution<br />Investigating Plant Mineral Deficiencies<br />
13. 13. The strength of Plant Fibres<br />
14. 14. Totipotency and Plant Tissue Culture<br />
15. 15. Name of the stain?<br />Toluedene blue<br />Why heating the slide?<br />Increases intake of stain by cells<br />Why adding HCl?<br />Softening the cell wall and helps in individual cells separately<br />Observing Mitosis<br />
16. 16. The Vitamin C content of Fruit Juices<br />