The rate of photosynthesis in the elodea Essay Example for Free

The rate of photosynthesis in the elodea Essay Put the boiling tube in a beaker surrounded by ice. Ensure the thermometer is standing upright in the beaker.   Note the initial temperature and maintain this throughout the experiment, either by means of adding or reducing the ice content.   Place the electric bench lamp towards the elodea specimen   Allow the elodea specimen to settle for five minutes or so.   On the fifth minute start timing for a further five minutes and count the amount of bubbles observed. Note: The same procedure must be carried out for the other two experiments, only altering the content outside the boiling tube. In order to keep the water temperature at 45o C, it is advised that cool water or some heated water (from the kettle) is added depending on the temperature observed. Prediction: I predict that when the elodea specimen is placed in ice, a few (one or two) oxygen bubbles will be observed, therefore photosynthesis will be limited. When the elodea specimen is placed in water at 45o C, more bubbles will be seen and hence the rate of photosynthesis will increase At room temperature, some bubbles will be seen but much less compared to the 45o C investigation, since the temperature is in between. Results: Ice: Time (minutes). Number of bubbles observed 1 1 2 1 3 3 4 0 5 0 Total: 5 Water maintained at 45o C: Time (minutes) Number of bubbles observed 1 3 2 10 3 12 4 3 5 1 Total: 29 Water at room temperature (tap water): Time (minutes) Number of bubbles observed 1 0 2 2 3 3 4 3 5 3 Total: 11 Discussion: From looking at my results, it appears to be that my prediction is reasonably accurate. As mentioned in my prediction, a few bubbles were observed when the elodea was placed in ice. This is because the cells within the elodea specimen eventually die. This can be explained by the concept of enzymes, which operate best at optimum temperatures. Placing the elodea in a cold environment, such as ice means that the temperature is extremely below the optimum. This inevitable leads to enzyme denaturation and only some bubbles are seen during the first two minutes prior to the denaturation. Consequently, there is some photosynthesis taking place. When the elodea cell is placed in water which is maintained at 45o C, the number of bubbles sighted increase rapidly (particularly in the second and third minutes). Notice for the fourth and the fifth minutes, the number of bubbles observed start to decline. This may well be to the fact that the temperature was not controlled as intended, and possibly exceeded 45o C, thus causing the enzyme to denature. Hence a decrease in photosynthesis is observed. When the elodea specimen is placed in water at room temperature, the number of bubbles observed are more or less the same. This is because the temperature of the water is fairly below the optimum, (which is believed to be 45o C) and therefore the rate of photosynthesis is limited. Evaluation: Despite the results fairly matching the prediction, the method used is rather unreliable. More repeats (i.e. three repeats) could have been put into practice as this would have allowed me to calculate an average and hence raising the reliability of the results. The temperature range is rather limited and so the results would have been more accurate by employing a variety of temperatures. This would have allowed me to pin-point exactly the optimum temperature of the enzyme, which is involved in photolysis. Looking at the results above, there was an incidence where the temperature was not properly controlled (the ice investigation in which 3 bubbles were noted in the third minute). I believe using a water bath would have allowed me to maintain the temperatures more precisely and save time as oppose to using a kettle. I recall whilst doing the experiment that the elodea specimen was placed somewhat close to the window. Light from the sun could have also played an important part of distorting the results because an increase in light intensity also contributes to an increase rate in photosynthesis. Therefore if this experiment is to be carried out again, it would be ideal to make use of the window blinds. Not forgetting to mention that the distance between the bench lamp and the elodea specimen was not fixed, and was varied during each investigation. This might have caused a slight degree of anomaly in the results. Having acknowledged this inconsistency has made me aware of what is required in the actual investigation. It can be argued that counting the number of bubbles can be deceiving and therefore another method should be put into consideration. An alternative way of doing the same experiment more accurately can be achieved by using a photosynthometer. A freshly cut strand of the plant is suspended upside down in a boiling tube. The healthy strand of elodea produces bubbles of oxygen gas when brightly illuminated (i. e. with a bench lamp 10 cm away from the elodea specimen) at different temperatures. The bubbles emerge from the cut end of the stem and are collected in a bulb at the base of the apparatus. From here, the oxygen gas can be drawn into the capillary tube by means of the syringe. The volume of oxygen gas collected in five minutes gives a direct measurement of the rate photosynthesis. Apparatus and Justification: Apparatus Justification of Apparatus x1 Clamp stand (with capillary tube). A lot of apparatus are involved, some of which that need to be held at a constant height above the water bath (i. e. the boiling tube with the elodea specimen). x1 Capillary tube with ruler.   Used to measure the length of the oxygen bubble(s).   Hence the volume of oxygen can be calculated. x1 Boiling tube   The use of a boiling tube is necessary as oppose to a test tube because its large enough to allow the elodea specimen to fit in with ease. x1 Elodea Canadensis specimen (10 cm long)   The elodea specimen is the basis for this investigation.   Allows the hypothesis to be tested. x1 5 ml syringe A 5 ml syringe is necessary to allow oxygen bubbles to be drawn in the capillary tube. No other apparatus can be substituted for this task. x1 30 cm Ruler   Used to measure the length of the elodea specimen, making sure that the length is constant for each investigation. To ensure a fair test. x1 Scalpel Used to cut the elodea specimen to the desired length with precision. x1 Plastic Tile   To aid in cutting the elodea specimen. To prevent any damage to the work bench. x1 Electric bench lamp with 100W filament bulb   Used to ensure a fair test as every investigation will be illuminated by a lamp at a set distance. To ensure the results are not influenced by light intensity but solely the temperature. x1 Thermometer   Used to ensure the temperature of water bath is correct, and hence to promote reliability of results. x1 Stopwatch   Used for timing the investigation for 10 minutes (five minutes for the settling of the elodea specimen and another five minutes for the investigation). x1 Beaker and ice blocks   To be used for the 0o C investigation.   To see if there is any photosynthesis evident at freezing level. Proposed Method: Diagram12: 1. Set up the clamp stand as shown above. 2. Get hold of a plastic tile and a scalpel and cut the elodea specimen at a length of 10 cm. 3. The cut end has to be inserted into the calibrated capillary tube as shown above. 4. Lower the capillary tube into the water bath, ensuring half of the boiling tube (containing the elodea specimen) is immersed in the water. 5. Place the bench lamp 10 cm away from the boiling tube. Ensure the light is directly facing the elodea specimen. 6. After setting all the apparatus up, pull the syringe on top of the capillary tube in order for the water to get into the capillary tube. This removes any air bubbles initially present in the capillary tube. 7. Place the thermometer into the water bath (or beaker in the case of the ice investigation) and turn the light on. The elodea must be allowed to settle for five minutes. 8. Time the investigation for a further five minutes by using a stopwatch. 9. On completion of the five minutes, switch the lamp off and remove the clamp stand along with the rest of the apparatus out of the water bath. 10. Pull the syringe to draw the oxygen bubbles into the capillary tube and measure the length of the bubble(s) simultaneously by making use of the ruler. 11. Note down the length of the bubble(s) on paper. 12. Repeat the same procedure three times for each temperature using the same elodea specimen. 13. Once the three trials are complete, move on to the next temperature. and carry out steps 1 -13 Ice investigation:   Get hold of the elodea specimen and place it in the boiling tube.   Put the boiling tube in a beaker surrounded by ice.   Note the initial temperature and maintain this throughout the experiment, either by means of adding or reducing the ice content.   Follow steps 5-13 above. Note: If an anomalous result is encounter during the duration of the experiment, it is advised to do that particular investigation again. Acknowledgements: 12- Diagram modified from A-Level biology Revised Edition by W D Phillips and T J Chilton, page 69. Analysis of Variables: Independent variable: The independent variable is the variable, which has to be manipulated in order to get the desired results. In this case, the independent variable is the temperature of the water baths. To obtain more accurate results, I have included temperature readings ranging from 0-65o C, in intervals of five. Three readings will be taken for each temperature and compared. Dependent variable: This is the variable which responds to the fixed conditions and which is used to test the hypothesis. In this case, the dependent variable is the volume of oxygen released by the elodea specimen. The length of the oxygen bubble(s) is going to be measured at the end of the five minute interval. This can be used to deduct the volume of oxygen produced by multiplying the length of the bubble(s) by pie, which is then multiplied by 0. 82 Fixed variables: These are variables, which have to be kept constant throughout the experiment in order to obtain accurate results. These variables cannot be manipulated at any time of the experiment. Some of the fixed variables are listed below: The light intensity (distance between the bench lamp and the elodea specimen): This can be kept constant by ensuring the elodea specimen is 10 cm away from the bench lamp. It may well be convenient reassure the distance with a ruler. The preliminary work I did have done has highlighted that 10 cm happens to be an ideal distance for sufficient photosynthesis to be followed and thus reliable results can be obtained. However if the distance between the bench lamp and elodea specimen is shorter than 10 cm, then this will have a major impact on the results. The increase in light intensity shall inevitably results in an increase in the volume of oxygen noted and thus distorting the results. Similarly if the distance is greater than 10 cm, then this decrease in light intensity shall contribute to a decrease in rate of photosynthesis and thence slowing down the rate at which the oxygen bubble(s) are released13. Therefore it is vital that this distance is kept constant throughout the experiment to ensure a fair test. * The number of leaves on the Elodea plant: The number of leaves will be kept constant throughout the whole experiment by using the same elodea specimen. The reason for keeping the same number of leaves is to ensure that the surface area provided by the leaves is the same in each investigation. Having the same number of leaves will provide the same surface area. If the number of leaves were different in each new investigation, then the number of leaves would be the independent variable. The more leaves there are the larger the surface area, and more light energy will be trapped by the leaves and a greater proportion of it will be converted into chemical energy14. Therefore more oxygen will be given off. On the other hand, a fewer amount of leaves shall results in a low yield of oxygen. In both cases, the results will be distorted if not controlled. Acknowledgements: 13- Letts Revise A2 Biology by John Parker, page 26 14- Revise A2 biology by Richard Fosbery and Jennifer Gregory; page 21 Reliability: To obtain more reliable results, three measurements would be taken in the same condition. The reason for this is that if in case, an error was made on the first attempt, the error can be amended and on the second attempt. After doing the experiment, if any of the results are anomalous then the experiment should be repeated. Results obtained can be compared to the previous results to see if there is an agreement. Light from the sun can also play an important part of distorting the results because an increase in light intensity also contributes to an increase rate in photosynthesis. Therefore it would be ideal to make use of the window blinds to promote reliability of results. Temperatures are monitored precisely by the water baths. However it is sometimes observed that the temperature of the water bath goes up or down by a degree or two. The temperature can be maintained by means of adding or removing ice to the water baths. Due to the limited number of water baths, there may well be the case of sharing a water bath to five others. This means five additional bench lamps would have an impact on my results (as light intensity increases rate of photosynthesis). The lamps may also contribute to the water baths getting hotter than required. Therefore it would be wise to carry out the investigation individually. When the apparatus are set up, the syringe (on top of the capillary tube) must be pulled to draw the water into the capillary tube. This will remove any air bubbles initially present in the capillary tube and thus leaving no ambiguity. Results: Table: showing the results I obtained during the investigation Temperature (o C) Length of Oxygen bubble (mm) Volume of Oxygen (mm) Rate of photosynthesis (mm3/min) Average rate of photosynthesis (mm3/min).

prejudice in to kill a mockingbird :: essays research papers

Prejudice is arguably the most prominent theme of the novel. It is directed towards groups and individuals in the Maycomb community. Prejudice is linked with ideas of fear superstition and injustice. Racial prejudice consumed the mob (pg 166), which wished to prevent Tom even gaining a court hearing, the most basic form of justice. This is probably the fiercest form of prejudice in the novel. The abolition of slavery after the civil war gave blacks the same legal position as many whites in America. This initially made Blacks ´ lives harder because now the Whites saw them as competitors for jobs during the 30s depression. Fear and paranoid led to the Whites believing that the Blacks desired all the whites had, including their women. Aunt Alexandra ´s attitude to Calpurnia The Missionary tea ladies ´ comments about the Blacks Segregation of White and Black in Maycomb Dolphus Raymond - White man living with Black woman Class & Family Group is recognised by Jem on page 249 â€Å"There are four kinds of folks in the world†¦Ã¢â‚¬  -  · Finches & neighbours: White middle-class  · Cunninghams: Badly hit farming community  · Ewells: Lowest class of whites ‘White Trash ´  · Blacks: Seen as bottom of social strata Due to the abolition of slavery there was no longer a clear-cut line between the Ewells and the Blacks; skin colour did not make them any better. When Tom said in the trial that he felt sorry for Mayella (a crime worse than rape in the jury ´s eyes) - the lowest class showing superiority for a class above themselves. The white community was frightened for their own position in society; the only reason Tom was found guilty was to maintain the traditional hierarchies. Alexandra is obsessed with heredity and educating Scout and Jem of their superior family background - she will not allow Scout to bring home a Cunningham to play, nor will she allow her to visit Calpurnia at her home. Everyone in Maycomb has a particular â€Å"streak† (pg 143), mean streak, drinking streak etc. There is a lot of pigeon holing families (pg 145). Gender - At the time the novel is set, women were still regarded as unequal to men. Scout learns this from:  · Miss Maudie in terms of religion (pg 50)  · Atticus in terms of the law - no women on juries  · Alexandra in expected terms of dress and behaviour However, there was an idealised view of women held at the time - the Southern Gentleman was excepted to be chivalrous to Southern Belles and that these women were to be protected and almost worshiped.

Operation Zapata

Operation Zapata, or invasion in the Bay of Pigs, was developed by the CIA as a way to replace Castro' s regime by non-communist government friendly to the USA. The initial plan of the operation was revised greatly: â€Å"Kennedy thought the plan exposed the role of the United States too openly† (Sierra, J. A. , 2008). Revised operation had little chances to succeed (Sierra, J. A. , 2008), and several major failures occurred during performance of the invasion (The Bay of Pigs, n. d. ), resulting in failed operation and imprisonment of almost all CIA-trained invading troops.Initial plan was well thought out and had much more chances to succeed, but interference from the new President and his advisors made this impossible to perform and underlined dependence of intelligence agency, its activities and plans from external decisions. Cuban missile crisis was a logical consequence of failed operation Zapata. Castro feared of military interventions from the USA and decided to agree f or placement of Soviet intermediate-range nuclear missiles in Cuba (An Overview of the Crisis, n. d. ) in exchange for training and funding of Cuban army. This activity soon was discovered by CIA (Simkin J., n. d. ). Kennedy ordered a naval blockade of Cuba and demanded USSR to remove all missile bases and their content (Goldman, J. , 1997), and the crisis was launched. Due to efficient performance of intelligence agency critical information about potential enemy activity was obtained beforehand and actions that ensured national security were taken in time. If operation Zapata would be successful, Cuba would have been ruled by the non-antagonist government and USSR would have received no possibilities for the placement of nuclear missiles so close to the US territory.If intelligence had failed to discover Soviet activity on the Cuba, national security would have been endangered greatly because of Soviet nuclear missiles placed so close to the national borders. Both of these examples show how crucial is effective and unhindered performance of intelligence divisions to the national interests, for intelligence proved critical role in both of accidents mentioned. 1. An Overview of the Crisis. (n. d. ). In ThinkQuest Library. Retrieved January 8, 2009, from http://library. thinkquest. org/11046/days/index. html 2. Goldman, J. (1997). The Cuban Missile Crisis, October 18-29, 1962.Retrieved January 8, 2009, from http://www. hpol. org/jfk/cuban/ 3. Sierra, J. A. (2008). Invasion at Bay of Pigs. – The Plan. Retrieved January 8, 2009, from http://www. historyofcuba. com/history/baypigs/pigs3. htm 4. Simkin, J. (n. d. ). Cuban Missile Crisis. Retrieved January 8, 2009, from http://www. spartacus. schoolnet. co. uk/COLDcubanmissile. htm 5. The Bay of Pigs. (n. d. ). In John F. Kennedy Presidential Library and Museum: Historical Resources. Retrieved January 8, 2009, from http://www. jfklibrary. org/Historical+Resources/JFK+in+History/JFK+and+the+Bay+o

One More Show Essay Example - 998 Words

One More Show By age of seven I was sick of school and I wanted out by whatever means. I went Dorsa elementary school, a local school in East Side San Jose. Coming from a Latino background, I was at a disadvantage because English was not my first language. So fix this the principle Mrs. Rodriguez decided to have an after school program with the parents permission of course. This program was meant to keep non native-english speakers for a one to two hours after school. Being in class was hard enough because I didn’t understand what the teachers were saying, or cared about what our learning. I used in sit in the back small classroom, staring at the white board or wall, dazed into space. My hands were usually on underneath†¦show more content†¦After climbing the fence I used to walk or run to my house. After getting home, I usually took a quick nap, then enjoy the day watching cartoons. This cartoon where shows like Clifford, whats New Scooby Doo, Ed Edd n Eddy, Codename Kids Next Door, Johnny Bravo, Static Shock, Justice League, Samurai Jack, Top Cat, Rob ot Boy etc. While watching the cartoons I used to mimic what the characters were saying. Some examples when I watch Ed, Edd n Eddy I used say phrases like â€Å"dork,† â€Å"sockhead,† â€Å"Son of a Shepherd† †¦. Ironically this how I learned how to speak, write, and read English, as well as draw. Sometimes for the fun of it, I used to draw cartoon characters because I like how they look. I sat down, grabbed a random paper, crayons and draw what I remembered about a character. This where my passion for drawing came from. Unfortunately, not everyone agrees with my method since they found it was considered ditching. I sent multiple times to Mrs. Rodriquez office and she always asks me â€Å"Why do I ditch† or â€Å"How do it†. I replied I just climb the fence and because is boring. My used to come to the office as I waited for her in an empty room. The principle would tell me that she was worried about me since she believed I wasnt learning, a nd she gave my mom statistics stating if I keep this behavior at an early age I would end up dropping out in the future and possibly incarcerated. I never believe thisShow MoreRelatedEssay On Portfolio Reflection1248 Words   |  5 PagesMy Portfolio Reflection Memo below indicates that I achieved this course learning outcome. CLO1 My essay 2 shows that I can develop an essay through the draft and revision. That is focused around a central idea. For example, my thesis has my main idea and all my body paragraphs relate to that. Here is my thesis, â€Å"I agree with her opinion, because although finding solutions that empower and equip children with knowledge to help them cope better with unfairness may not be easy. 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