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Global warming

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Earth’s temperature is maintained with the aid of specific gasses in the atmosphere that retain heat. Those gases are referred to as the green house gasses. The ones that have the largest warming effect are water vapor (e.g. clouds) and carbon dioxide. There are other gases that have a lesser impact such as methane and nitrogen oxide.

In order to observe this we conducted an experiment in which we tested the impact of carbon dioxide on temperature. We had two jars that represented the two worlds, each had a bit of water in it as it represented the ocean or sea. The jars were sealed and displayed under equal lighting from a lamp, representing the sun. The only difference was that one of the worlds has a higher carbon dioxide concentration delivered in it. The temperature was then measured in each of the two worlds and the following data was observed:

graph

Validity

The experiment was hence unsuccessful as the anticipated result was the opposite of the one presented above. Since the experiment was supposed to represent global warming, the world with the high carbon dioxide capacity should have had a higher temperature as the gas retains heat.

Reliability and limitations

The results are not reliable due to several limitations that hindered their accuracy:

  1. The experiment was carried out for a short time span. Global warming is a process that has been evolving for centuries and we only observed our model of the world for about 30 minutes. Perhaps if they were left for a longer time, the results would have been different as it would have given the CO2 more time to increase the temperature. Next time it should be left over a longer period of time.
  2.  The two jars were put under a lamp but they were also surrounded by broad daylight which may have affected the result. The position of the lamp was also decided by hand and hence could have led to some minor inequalities. Next time the experiment could be done in a dark room as to limit other sources of light and represent space.
  3. The thermometer values were often between two bars at which each group rounded differently, leading to a difference in results. In the future we should strive to be exact as possible or agree to always round at either the higher or lower value.
  4. In order to seal the jars we used clingfilm which is not very reliable as it hardly sticks to round surfaces and could leave holes. This can alter the CO2 quantity within the world as the gas could just escape through the openings.  In order to prevent this, I suggest next time we use an actual, impermeable lid.

Mesocosm

Mesocosms are enclosed environments that allow a small part of a natural environment to be observed under controlled conditions.

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  1. Building a verdant foundation
  • Add a bottom layer of pebbles, gravel or sand – this layer exists for drainage (smaller vessels require thinner rock layers)
  • Add a second thin layer of activated charcoal – this will prevent mold and help to aerate the soil
  • Spread a thin cover of sphagnum moss (or use an organic coffee filter) to create a barrier between the lower layers and soil
  • The final layer is the pre-moistened growing medium (i.e. potting mix)
  1. Selecting the right plants
  • Ideally, choose plants that are both slow growing and thrive in a bit of humidity (e.g. most ferns, club moss, etc.)
  • Inspect the plant thoroughly for any signs of disease or insects before introducing to the terrarium
  1. Maintaining appropriate conditions
  • Ensure the terrarium is placed in a location that provides a continuous source of light
  • Locate the terrarium in a place that does not experience fluctuating temperature conditions (i.e. avoid direct sunlight)
  • Do not initially over-water the plants – once the right humidity is established, a terrarium can go months without watering
  • Occasional pruning may be required – however, as level of soil nutrients decrease, plant growth should slow down

Species, communities and ecosystems

 

Species classify as groups of organisms that can interbreed to produce fertile offspring.

Autotrophs obtain inorganic nutrients from the abiotic environment. This means they are the producers of their own food.

Example: plants

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Heterotrophs in contrast, are consumers of food they did not produce themselves.

Example: Humans

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Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.

Example: earth worms

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Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.

Example: Fungi

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Investigating the effect of light intensity on the rate of photosynthesis of Elodea

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In this experiment the rate of photosynthesis is measured by counting the number of bubbles rising from the cut end of a piece of Elodea. The plant will be exposed to different light intensity in order to establish the correlation between light and rate of photosynthesis.  The independent variable is the light and carbon dioxide intake, the dependent variable is the number of released bubbles and the constant variable is the strand of Elodea.

Apparatus:

  • 2 test tubes in which to put the Elodea in
  • Elodea plants kept in a tank
  • Water I which to put the Elodea in as to observe the bubbles
  • Liquid CO2 in order to speed up the reaction

Method:

  1. Pour water into the two test tubes and add a strand of Elodea in each one, cutting the top off as to increase the photosynthesis rate.
  2. Add CO2 in order to speed up the reaction.
  3. Put one tube in the shade and expose the other to daylight.
  4. Observe the bubbles in both tubes after 1minute.

 

Outcome:

  • There were some bubbles in the light and no bubbles in the shade. This indicates that photosynthesis has a positive correlation with light. The more light is present the faster the process.

Maggot respirometers

A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide. They allow investigation into how factors such as age, chemicals or the effect of light affect the rate of respiration. In this experiment, I will be testing the respiration of maggots and its correlation with different temperatures. Therefore, temperature is the dependent variable and light, noise, time and number of maggots are the independent variable.

Equipment:

  • Maggots in order to have a representative living organism
  • Respirometer to measure the respiration
  • Hydrogen carbonate indicator in order to measure the Ph value
  • Pipette in order to measure the carbonate indicator more exactly

Method:

  1. I poured in 2,5ml of the hydrogen carbonate indicator in two different respirometers.
  2. I added 10 maggots in each respirometer.
  3. One cup was left at room temperature (20°) and the other was put in a water heater that possessed the temperature of 30°.
  4. The different cups were left in their environment for an unmeasured amount of time and the color of the indicator was observed.

Expectation:

 When heat increases the enzyme Collison would increase as well and therefore the carbon dioxide amount would rise.

Result:

  • The indicator in the respirometer in room temperature had turned orange and therefore possessed the Ph rate of 8.
  • The indicator in the respirometer in the heater had turned red and had the Ph rate of 8,6.

The results did not relate to the initial hypothesis. This indicates that there were multiple errors that hindered the desired outcome. For example, whilst the number of maggots was the same some of them were dead and hence did not practice respiration.

The lack of timing led to further inaccuracies. The respirometer in room temperature stayed longer than the one in the heater as we drowned our first experiment and had to redo it.

Another critical point is that the room we did the experiment in was too cold and therefore did not have the exact room temperature of 20°. This could have tempered with the final results as the temperature difference was greater than anticipated.

The effect of temperature on amylase

 

Enzymes are known as biological catalysts, composed out of proteins. This means that they speed up chemical reactions. They are very efficient and used in all processes inn living organisms, including digestion, respiration, and photosynthesis. Enzyme activity depends upon several factors including temperature and pH. In thus investigation I will look at the effect of temperature on the enzyme amylase, which is found in saliva and is used to break down starch into maltose as part of digestion.  One can measure the activity by seeing how long it takes for the starch to disappear by testing for it with iodine.

The purpose of this experiment is to determine the temperature at which amylase is most effective at digesting starch.

 

Hypothesis:

Hypothesis As the reaction temperature of amylase solution and starch solution increase, the reaction rate of amylase and starch will increase.

The experiment was conducted with several temperatures: 0°; 20° (room temperature); 30°; 35°; 63°

Materials:

10ml 0.2% starch

10ml 0.3% amylase

Several drops of Amount of iodine

 Uncertainties: quantities were never precisely measured but compared only by sight

Apparatus:

  • spotting tile in which to put the iodine test
  • test tubes, in order to contain liquids
  • Disposable pipettes, in order to transport liquids
  • Thermometer, in order to measure the temperature
  • Heater in order to reach certain temperatures

The independent variable is the temperature. The dependent variable is the time which it takes for the starch to be broken down.

Method:

  1. Amylase and starch are poured into two separate test tube. Both should be 10ml and be at room temperature.
  2. The liquids are mixed together and put into a heated or frosting environment in order to reach the desired temperatures.
  3. A spotting tile is used and 5 drops of iodine are dropped into each of the wells.
  4. A small sample of the mixture is taken up by a pipette and is dropped in the first well. The color is noted. The process is repeated every 30 seconds until the iodine changes color, indicating the starch has been digested.
  5. The experiment is repeated several times in order to achieve ultimate accuracy.

Results:

The results can be interpreted easily from the following timetable:

Temperature (°C) Time for starch to disappear (s) Average time for starch to disappear (s)
0 120 120
20 70; 120; 20; 20 58
30 100; 100 100
35 15; 17 16
63 500 500

 

Evaluation:

  It can be observed that there is no obvious increase or decrease of the time span concerning the different temperatures. Since the results are rather random, the correlation is probably fairly weak. This could also be explained due to anomalies which occurred during the experiment and hence limited its accuracy. For example, the time between mixing the two liquids and adding them to the iodine was often not recorded and possessed different durations. This allowed the mixture to change its original temperature and either hindered or sped up the chemical reaction involved in digestion.

Another limitation was the fact that the amylase, extracted from our saliva did not possess room temperature as anticipated but was warmer because it was preserved in our bodies. Furthermore, the amylase was preserved in a glass jar in a cold room. It is highly unlikely that it too had a room temperature of 20°. This makes the foundation of the experiment vulnerable as it tempered with the initial approach that both substances should be of equal temperature.

An additional limitation is that the quantity of the amylase and starch were not measured by an exact proportion but rather by sight. This risks a difference between the amount of the substances and contributes to the inaccuracy of the experiment. The measuring has been done in the same fashion during all the experiment rounds. This does not only bring the problem of a wrong proportion between the substances but also between the different trials, making the result for the average time even more unreliable.

Each group conducted a different amount of trials. This made some final results more reliable than others as the mean was more precise and able to generalize. We can only assume that the results of the groups that only made one experiment are right as we have nothing to compare it to. There’s always the risk of it being a special case.

The time span in which the mixture was dropped onto the different iodine wells was not always precisely 30 seconds as the beginning of the experiment and the timer weren’t often synchronized by a couple of milliseconds. If the digestion happened at a fast pace, as it did in room temperature, those would have been vital for the end result. The different rounds were also often a couple of seconds earlier or later than intended as it took a while to drop only the needed amount of the mixture which was fairly small.

Conclusion:

The experiment is basically not successful, the test result is not essential and does little to prove my hypothesis.

Make cat milk great again- immobilized lactase used to make lactose-reduced milk

Equipment

10 ml plastic syringe

 silicone tubing, about 7 cm long, to fit syringe

adjustable laboratory tubing clip

Retort stand, boss and clamp (to support enzyme column)

2 small beakers (100 ml) or disposable plastic cups

Tea strainer

Glass stirring rod

 

 

Materials

2 ml lactase enzyme

8 ml 2% sodium alginate solution

100 ml 1.5% calcium chloride solution

50 ml milk

Semi-quantitative glucose test strips

Procedure

  1. Mix the enzyme with the sodium alginate solution, then draw it up into a 10 ml syringe.
  2. the alginate-enzyme mixture a drop at a time from the syringe to the calcium chloride solution and observe the formation of small beads. The beads, which contain the enzyme immobilised in a matrix of calcium alginate, should be allowed to harden for a few minutes.
  3. Separate the beads of immobilised enzyme from the liquid with the tea strainer.
  4. Carefully tip the beads into the syringe barrel.
  5. Close the tubing on the syringe barrel using a tap.
  6. Test the milk before treatment using the glucose test strips, to ensure that it does not contain any glucose.
  7. Pour a small volume of milk over the enzyme beads, then undo the clip and allow the treated milk to run into a small beaker.
  8. Test the milk leaving the column using the glucose test strips. If necessary, return the treated milk to the column until the desired concentration of glucose is achieved.

Outcome:

The beads break the Lactose into Glucose and Galactose and hence the test strips change their colour, indicating a richness of Glucose. The milk is now appropriate for the cat to consume it.