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  • Level: GCSE
  • Subject: Maths
  • Word count: 1296

The purpose of this experiment was to find out what the effect of the auxin 2,4-dichlorophenoxy acetic acid is on the growth of pea plants.

Extracts from this document...



        The purpose of this experiment was to find out what the effect of the auxin 2,4-dichlorophenoxy acetic acid is on the growth of pea plants. After research on the topic the hypothesis was developed. The hypothesis was that if the pea plants are grown with 2,4-D hormone then they will not grow as fast as the control group of plants because the hormone inhibits growth. To perform this experiment pea plants were grown for two weeks without any kind of paste. Observations were taken and measurements made. Then the hormone paste was applied to half of the plants and the other half got a paste containing no hormones. For the next two weeks, observations were made and the plants were measured twice more.

        The results show that after the pastes were applied the pea plants with the hormonal paste actually became shorter, on average. These plants were looking withered. The plants with the control paste continued to increase in height and were healthier than the experimental group. After two weeks with the hormone paste the plants average height is less than it was after one week of hormone paste.

The effect of the auxin

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Control group:  plants with the control paste

Sample size: 11 control plants and 10 experimental plants

Replication: 1

Materials: plant containers, peas, graduated cylinder, water, soil, artificial light source, metric ruler, hormone paste, control paste


1.        Label containers.

2.        Fill 2/3 full with soil.

3.        Water soil so it is like a damp sponge.

4.        Place two peas in each container, about 1 inch deep, and cover with soil.

5.        Place under artificial light source.

6.        Let grow for two weeks.

7.        Keep watered so soil is damp.

8.        Measure after two weeks.

9.        Apply hormone paste to experimental group and control paste to control group.

10.        Let grow another two weeks.

11.        Measure plants after each week with the paste.

Safety hazards: There are the usual safety hazards such as cuts from broken glass or slips from spilt water. In this lab attention must be paid when working with the hormone. When applying 2,4- D to the plants a swab should be used to keep the hormone off the skin. Also, when measuring the plants one must watch out to keep skin of off the hormone.


The f-test and t-test are used to compare the growth of the control and experimental groups after two weeks with the hormone paste.

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        If this experiment were to be done again, it would be better to take measurements more often. Also, it would be the hormone should have been applied to a specific place instead of on both the leaves and stem. Had the experiment gone on during a longer period of time there would be more definite results. The average height of the control group plants would exceed those plants with hormones applied to them. Another thing that should be controlled is the amount of paste applied to each plant. A larger sample size would be beneficial also.

        The research is practical in that it provides away to control plant growth by the use of hormones. After learning about the results one could use the auxin 2,4-D to inhibit plant growth. This information could be valuable to botanists and home gardeners. These two groups deal with plants and for them it is essential to understand what affects the growth of plants.

        Future research based on this project can study the effects of different concentrations of 2,4- D or the effects of this hormone on various types of plants. Another thing that can be studied is the how the location of where the hormone is applied causes different results.

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