In this experiment, mung bean seedlings and Brine shrimp eggs were used to study the effect of temperature on the rate of germination of seedlings and the rate of hatching of eggs.

Title :

Investigation on the effect of temperature on the development of organisms

Abstract :

The purpose of carrying out this experiment is to investigate the effect of different temperature on the development of organisms. The effect of increasing temperature on the development of living organisms can be modeled in the laboratory by measuring the germination of plants seedlings and the hatching rate of living organisms. This experiment is to show the effect of rising temperature on the earth or in other words, global warming on the living organisms. It is also to show which temperature is the most suitable for living organisms to live in. Temperature plays an important role on the enzyme activity which in turn affects the whole organism. In different salinity, living organisms also will have a different rate of development. In this experiment, mung bean seedlings and Brine shrimp eggs were used to study the effect of temperature on the rate of germination of seedlings and the rate of hatching of eggs. Three different temperatures that is 20oC, room temperature of 25oC and 30oC were used to investigate the effect of temperature on the development of both mung bean seedlings and Brine shrimp eggs while 1% and 1.5% salt solution were used for the Brine shrimp eggs. The number of seeds germinated, length of the radicles and the number of leaves were measured to determine the rate of development of mung bean seedlings. On the other hand, the number of eggs hatched, number of shrimps alive and mobility of shrimps were observed in order to examine the development of organisms. In conclusion, the optimum temperature for the development of organisms will be the room temperature that is around 25oC and the optimum salinity for the development of Brine shrimp is at 1.5% salt solution.

Problem statement:

Does global warming affect the rate of development of organisms? What is the effect of increased temperature on the rate of development of organisms? What is the best salinity of water for the development of living organisms?

Hypothesis :

Global warming does affect the rate of development of organisms. As the temperature increases, the rate of development of living organism increases until the optimum temperature that is room temperature of 25oC. Beyond the optimum temperature, the rate of development decreases with further increased in temperature. The rate of development of organism increases with higher salinity of solution until the optimum salinity of not more than 3%.

Objective :

To investigate the effect of temperature on the rate of development of living organisms.
To develop certain experimental skills, such as working safely, producing valid results, recording results and drawing valid conclusions from results.
To learn the functions of a compound microscope and use it to examine the development of Brine shrimp eggs.

Introduction :

Global warming is the general increase of temperature in the environment. It is the increase in mean temperature of the Earth’s near surface air and oceans since the mid-20th century and it is predicted to be increasing continuously. The earth’s average temperature rose about 0.74 ± 0.18oC during the last century and mostly is due to anthropogenic causes such as burning of fossil fuels and deforestation (). It is widely believe that global warming is due to increase greenhouse gases, rise in carbon dioxide concentration and it may be cause by other reasons such as solar radiation and the position of the earth in the orbital. An increase in global temperature will cause the Artic and Antarctic ice to melt into the sea and causes the sea levels to rise. Temperature has a profound effect on the whole organisms as it will affect the enzyme activity in the organisms and thus, the development of the organisms.

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term which is used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulphates. It is an important ecological factor which can influence the types of organisms that live in that water of particular salinity. Organisms that can live in very salty conditions are classified as extremophiles while organisms that can withstand a wide range of salinities are euryhaline (). In this experiment, the different salinity of water solution is prepared by dissolving different amount of sodium chloride salts in water.

Mung beans seedlings are chosen to be used in this experiment to measure the rate of development of plants. Mung bean is the seed of Vigna radiate which is native to Bangladesh, India and Pakistan. The beans are small, ovoid in shape and green in colour. They are green in colour with the husk and yellow when dehusked. They are literally called green beans in our daily lives. They are commonly used in Chinese cuisine and generally eaten either whole with or without skins, as bean sprouts or used to make desserts. They are widely used in cooking because of their ...

This is a preview of the whole essay

Diagram shows mung beans

(Source : www.nutsonline.com)

On the other hand, Brine shrimp or its scientific name of Artemia sp is a type of aquatic crustaceans. Artemia are found globally in inland saltwater lakes but not in oceans. Brine shrimp eggs are metabolically inactive and can remain in total static for several years in dry oxygen-free conditions. Once they are placed in water, the cyst-like eggs hatch within hours. They have a biological life cycle of one year which they grow and mature to around one cm long (). Though it is just over a centimetre in size, it is a well-known species due to its importance as a food source for fish and crustaceans. Under magnification, they are elongated in shape and have eleven pairs of limbs. These characteristics give this organism a shrimplike shape (). In this experiment, the Brine shrimp is from Carolina, USA.

Diagram shows Brine shrimp

(Source : http://phytoshadd.com)

In this experiment, mung bean seedlings are soaked overnight. After that, 15 seedlings which have not germinated are chosen to be placed in a Petri dish on a cotton wool. The steps are repeated for two other Petri dishes to be placed at three different temperatures that is 20oC, 25oC and 30oC. On the other hand, three solution of 1% salt solution is prepared by dissolving 5 g of sodium chloride salt in 500 ml of mineral water in a beaker. One teaspoon full of Brine shrimp eggs is placed into each beaker. The three beakers are placed at three different temperatures. Another 1.5% salt solution is prepared and placed at room temperature. The development of mung bean seedlings in the form of number of seeds germinated, length of the radicles and the number of leaves were measured for three days that is 24 hours, 48 hours and 72 hours. The development of Brine shrimp is observed in the form of number of eggs hatched, number of shrimps alive and mobility of shrimps are recorded for the duration of three days.

Variables :

Manipulated variable : Temperature of surrounding and salinity of solution

Responding variable : Rate of development of organisms

Constant variable : The type of seedlings, the number of seedlings, the type of Brine shrimp, the amount of Brine shrimp in each solution.

Materials and Apparatus :

Seedlings of mung beans, cotton wool, Petri dishes, water, Brine shrimp eggs, sodium chloride salt, mineral water, teaspoon, glass rod, large beakers, compound microscope, cavity slides, small pipettes, weigh balance.

Procedure :

Germination of mung bean seeds

About 50 mung bean seedlings are soaked overnight.
About 1 cm thick of cotton wool is cut and placed in a sterile Petri dish. The cotton wool is wet thoroughly with water.
15 seedlings which are not germinated are chosen and lined up evenly in the Petri dish.
Steps 2 and 3 are repeated twice so that three samples of Petri dishes will be obtained.
The Petri dishes are placed at different temperature that is 20oC, room temperature and 30oC.
After every 24 hours for three consecutive days, the seedlings are observed and any changes are recorded. The number of seeds germinated, length of the radicles and the number of leaves are measured.

Hatching rate of Brine shrimp

5 g of sodium chloride is weighed using a weigh balance.
1% salt solution is prepared by dissolving 5 g of sodium chloride in 500 ml of mineral water in a large beaker.
Steps 1 and 2 are repeated twice so that three beakers of 1% salt solution will be obtained.
Another 7.5 g of sodium chloride is weighed and then dissolved in 500 ml of mineral water in order to produce 1.5% salt solution.
One teaspoon full of Brine shrimp eggs is placed into each beaker of solution and stirred gently.
As for the 1% salt solution, one beaker is placed at each temperature of 20oC, room temperature and 30oC.
As for the 1.5% salt solution, the beaker is placed at room temperature of 25oC.
Every two hours, each of the beakers is stirred with a glass rod.
After every 24 hours for three consecutive days, the shrimps are observed under the compound microscope to see the development.
Five samples of the Brine shrimps from each beaker are taken and observed. After observation, they are placed back into the respective beakers to allow them to develop fully.
The number of eggs hatched, number of shrimps alive and mobility of shrimps are observed and recorded.

Results :

Table 1 : The germination of mung bean seedlings

Table 2 : The hatching rate of Brine shrimp at 20oC in 1% salt solution

Table 3 : The hatching rate of Brine shrimp at room temperature of 25oC in 1% salt solution

Table 4 : The hatching rate of Brine shrimp at 30oC in 1% salt solution

Table 5 : The hatching rate of Brine shrimp at 25oC in 1.5% salt solution

Table 6 : The overall hatching rate of Brine shrimp

Discussion :

Explanation of the result obtained

From the experiment on the germination of mung bean seedlings, the optimum temperature in which the mung bean can germinate the fastest is at 25oC. The number of seeds germinated at 25oC is much lesser as compared to 20oC might be due to some of the seedlings are destroyed during preparation. They might be dead and therefore, cannot germinate. At the end of the third day, the length of the radicles and the number of leaves at 25oC are found to be the highest. Therefore, this shows that 25oC is the best temperature for the germination of plants. At 30oC, the mung bean seeds were found dead. This might due to the high temperature that destroys the enzyme in the beans and hence stop the process of germination. It might also due to the lack of water as at high temperature, the water from the cotton wool is absorbed at a faster rate. The cotton wool at 30oC was found to be dried as compared to the lower temperature.

From the experiment on the rate of hatching of Brine shrimp eggs, the optimum temperature in which the rate of hatching is the highest is found to be at 25oC as well. The total number of eggs in observation was counted. Then, the number of eggs hatch, the number of shrimps that were alive and the mobility of shrimps were observed and counted. The percentage was obtained by dividing them with the total number of eggs in observation. At the end of the three day, it was found that the number of eggs hatch, number of shrimps alive and the mobility of shrimps at 25oC were the highest as compared to other temperature. This is because 25oC is the optimum temperature where the shrimp can develop at the maximum rate without any decline in number as shown in 30oC. After 24 hours, it was found that the Brine shrimp develop better at 30oC because the rate of reaction is high at a higher temperature. However, the rate decreases as at high temperature, the enzyme in the eggs are easily denatured and destroyed and thus, the eggs can no longer develop fully. At low temperature, the rate is low and therefore, it was shown that as the time gets longer, the number of eggs hatch increases.

At 1.5% salt solution, the rate of hatching of Brine shrimp is higher as compared to 1% salt solution at the same temperature that is 25oC. This showed that the shrimps can tolerate different salinity of water solution up to a certain concentration that is 3% concentration. In fact, at 1.5% solution, it shows that the shrimps can develop better and therefore, shrimps can survive in around 1% to 3% salt solution.

Overall, it shows that the increased in temperature will cause the decrease in the development of organisms. This proves that with global warming, the rate of development of organisms in the natural environment will be affected.

Justification of the material and apparatus used

Mung beans were chosen to be used in this experiment because they are small and tiny. This characteristic enables a large amount of beans to be placed in the small Petri dish to ensure that the rate of development can be measured more effectively. Besides that, they can be grown easily and can be germinated within one day compared to other types of beans. Furthermore, they are easily available and are very cheap. In addition, their rate of germination can represent the rate of majority of all the living organisms. Besides that, cotton wool is used to germinate the mung beans seedlings because the germination of the seedlings does not need any nutrients. All they need is just water which can be easily available from wetting the cotton wool. Furthermore, the seedlings can grow faster with a thin cotton wool as compared to in soil. The process of germination can be observed more clearly as cotton wool is white in colour and do not hide the roots.

Brine shrimp eggs are chosen to be used in this experiment because of the ability of the brine shrimp cysts to remain dormant for long periods of time and easily hatched. It looks like a powdery brown substance but in actual fact, there are thousands of cysts or eggs surrounded by protective cases. When they are added to water, they will hatch into shrimp nauplii within a few hours (). Besides that, they are easily available at any pet display. Due to its short life span of one year, they are invaluable in scientific research, including space experiments ().

The different salinity of water solution is prepared by using sodium chloride dissolving in mineral water. Sodium chloride is easily available as common salt. Mineral water is used as the Brine shrimp is very sensitive to microbes. 1% salt solution is used to examine the effect of temperature on the rate of hatching of Brine shrimp because it is almost the same concentration of salinity where most Brine shrimps are found in their natural environment. They are found mostly in inland saltwater lakes and not in ocean. Therefore, a higher salinity of 3% to 6% of water solution is not used. However, when 1.5% salt solution is used, the rate of hatching increases, proving that 1.5% solution is also capable to provide the ideal environment for the development of Brine shrimp. It is shown that the Brine shrimp can tolerate different salinity and in fact, they can breed faster in a much higher salinity.

Replicates

Replicates are important in order to increase the accuracy of the experiment. The experiment on the germination of mung bean seedlings should be repeated at least three times for each temperature in order that the accuracy of the experiment can be increased. An average value will be calculated so that the accuracy of this experiment can be increased. The same method is used for three other temperatures. On the other hand, as for the rate of hatching of Brine shrimp eggs, ten samples are taken from each beaker so that an average value can be obtained. Ten samples are just a random estimation of the whole population as the eggs are very small and the whole eggs in the solution cannot be measured.

Validity and Reliability

To increase the validity and reliability of this experiment, the experiment should be repeated more than two times so that a more accurate result can be obtained. An average value is calculated by finding the mean of the value of the replicates. Comparison of the results obtained can be made with other groups so that the values will not differ greatly. This can ensure that the results obtained are valid and reliable. In order to increase the reliability of the experiment, make sure that the mung bean seedlings chosen to be used should not germinate first before placing them in the Petri dish. Besides that, when the samples for the Brine shrimp is taken to be examined under the compound microscope, care should be taken to ensure that they are placed back into their respective beaker and not throw away. The beakers should also be stirred occasionally so that the eggs will not stick to the wall of the beakers. If some of them do stick, they will lack of water and will not hatched. These will ensure that the results obtained are reliable and valid.

Possible Errors

Errors may have occurred if some of the seedlings used were dead and cannot germinate at all. Besides that, error will also occur if seedlings had already germinated before they are placed in the Petri dish. This will cause the seedlings to have a faster rate of germination as compared to other seedlings. In addition, aseptic technique is not used in this experiment. There might be contamination and affects the result of this experiment. Furthermore, if the beakers containing the Brine shrimp eggs are not stirred properly, this will reduce the accuracy of the experiment as some of the eggs will not have enough water to hatch. Not only that, human error can also result when the numbers of eggs are counted wrongly when observe under the compound microscope.

Risk Assessment / Precautions

Firstly, utmost care has to be taken care when handling glass wares such as beakers, glass rods and Petri dishes as they are fragile and can be broken easily. We should wash our hands with soap before and after the experiment to take care our personal hygiene. Be extra careful when dealing with sharp apparatus such as the forceps and scissors when cutting the cotton wool and transferring the seedlings into the Petri dish. Furthermore, do make sure that the amount of Brine shrimp eggs that are placed into each beaker is almost the same by using two half teaspoon instead of one full teaspoon which might reduce the accuracy of the number of eggs in each beaker. When measuring the eggs, care needs to be taken as not to destroy the eggs. Do not stir the eggs too hard as the eggs might be destroyed while stirring.

Suggestion and Improvements _

First and foremost, aseptic techniques can be carried out during the preparation of the mung bean seedlings so that the results of the experiment can be improved. Besides that, make sure that the cotton wool is wet thoroughly as this will ensure that the mung beans wil have enough water to germinate.

Conclusion :

(3806 words)

References :

Adds, J., Larkcom, E. and R. Miller. 2000. Exchange and Transport, Energy and Ecosystems. 204p. United Kingdom: Nelson Thornes.

Clegg, C.J. 2009. Edexcel Biology for A2. 205p. London: Hodder Education.

Fullick, A. 2009. Edexcel A2 Biology. 259p. United Kingdom: Pearson Education Limited.

King, T., Reiss, M. and M. Roberts. 1994. Practical Advanced Biology. 326p. United Kingdom: Nelson Thornes.

Nuts Online. 2009. Mung beans. Available from: . Accessed on 10th October 2009.

Rhode Island Sea Grant Fact Sheet. 2009. Brine shrim. Available from: . Accessed on 10th October 2009.

Wadsworth. 2009. Brine shrimp. Available from: http://phytoshadd.com/images/brine%20shrimp.jpgAccessed on 10th October 2009.

Wikipedia. 2009. Global warming. Available from: http://en.wikipedia.org/wiki/Global_warming. Accessed on 11th October 2009.

Wikipedia. 2009. Mung beans. Available from: . Accessed on 21st September 2009.

Wikipedia. 2009. Salinity. Available from: http://en.wikipedia.org/wiki/Salinity. Accessed on 11th October 2009.

Teacher Reviews

Here's what a teacher thought of this essay

Adam Roberts

30th of Jul 2013

**** A great deal of work has gone into this study. It is a pity that more than one independent variable is involved. More detail is needed in many places, and more complete explanations would allow a better understanding of reasons for decisions made about the experimental method.

Did you find this review helpful? Join our team of reviewers and help other students learn