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Effects of temperature on the development of a bean plant.

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Effects of temperature on the development of an organism Abstract Beans require a suitable temperature to germinate, one effect that temperature has is to regulate the rate at which enzymes digest their substrate. Temperature affects the kinetic energy at which particles collide. All enzymes have an optimum temperature at which the rate of reaction is at its fastest. If the temperature becomes too high the enzyme can become denatured preventing it from binding to its substrate. The results show that there is a significant correlation between temperature and the rate at which germination proceeds. Also the difference between the lines of best fit for broad beans grown at 20°C is close to that of beans grown at 25°C. The results do clearly show that there is a correlation between the temperature of the environment and the rate of germination. Introduction For a seed to successfully germinate there are several environmental factors which need to be met. These include: 1. An adequate supply of water 2. A suitable temperature 3. An appropriate partial pressure of oxygen 4. A suitable supply of light Water and Seed Germination Water is the crucial step in the activation of germination; it is responsible for activating the enzymes that stimulate the growth of the embryo. Once the enzymes have been activated the immature seed begins to consume the nutrients inside the endosperm. Beans take in water via a process known as osmosis. Osmosis occurs when a water molecule moves from an area of high water potential to one of lower potential. Water enters into the testa through the micropyle1. Bewley, J.D. (1997). Seed germination and dormancy. Plant Cell 9, 1055-1066. Beans Awakening from the Dormant Phase When enough water has entered through the micropyle certain chemical processes begin. Before water has entered the seed it is said to be in a dormant phase. The embryo remains dormant due to the inhibitory effect of the hormone abscisic acid and the seed coat is dense and tough enough to prevent the penetration of gas and the inhibition of other enzymes2. ...read more.


The levels of light can be kept constant by putting dark paper around the jars. The volume of water added to the jars each day will be done at the same time. Levels of oxygen will need to be kept constant as well in addition to this so that the seed can easily germinate. This will be easy to do as the jars will be left open to allow ventilation. Oxygen is needed in a similar way to water; the seed takes in the oxygen until the seed coat bursts, letting out the root. If the seed is deprived of oxygen then it will take a lot longer for the seed to germinate. The duration of which the beans are left for should be the same for each dish. If a certain set of beans are left for a lot longer then some anomalous results could appear because the certain set of beans had been given more time to germinate and grow. The number of beans should be the same in each dish. It wouldn’t directly affect my final results but it will be a lot more easy and fair to compare the beans in each jar and not a selected number of beans. Place of incubation 3ËC - fridge 14ËC – living room cupboard 20ËC - airing cupboard 25ËC – green house Results 3ËC Bean 1 Bean 2 day 1 0 0 day 2 0 0 day 3 0 0 day 4 0 0 day 5 0 0 day 6 0 0 day 7 0 0 14ËC Bean 1 Bean 2 day 1 0 0 day 2 0 0 day 3 1 1 day 4 2 2 day 5 4 4 day 6 6 7 day 7 7 9 20ËC Bean 1 Bean 2 day 1 0 0 day 2 7 6 day 3 11 9 day 4 17 15 day 5 20 18 day 6 24 23 day 7 27 25 25ËC Bean 1 Bean 2 day 1 0 0 day 2 ...read more.


This would mean that they would no longer be able to bind to their substrate and therefore not be able to produce the substrates needed for growth. This experiment does not show that and therefore only a limited conclusion can be made as to the effect of temperature. To improve the results incubation of the beans needed to occur at a temperature range over 30°C. This would then have allowed a more accurate optimum temperature for broad beans to be identified. Although all precautions where taken to reduce fluctuations in the temperature at which the broad beans were incubated. It is obvious to suggest that the temperature of each of these Although temperature is a significant factor in the growth of beans, there are other abiotic factors that limit seed growth; water, oxygen, light and space. Although the effect of these factors was limited there is nothing to suggest that they could have affected the results. It would have been interesting to set up a control in this experiment where water was not added to the beans on the first day, to see what effect this would have had. A further experiment could have been carried out to determine what effect rationing water would have had on the beans. This could have been done by keeping the beans at a particular temperature a removing the supply of water after 1, 2, 3 … and up to 10 days. This would have shown when water stops becoming the limiting step. I would also like to determine the affect that light intensity has on the rate of germination of seeds. In this experiment the seeds where placed in different places and it is evident that some of the seeds may have been in light longer than others. I would like to determine if germination at a constant temperature is affected by the intensity of light. This could be achieved by using polyethylene networks over the light source to produce different light intensities of 100, 50 and 25%. ...read more.

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