Investigation of Effects of Geotropism

Investigation of Effects of Geotropism

Geotropism is the growth of shoot away from gravity and of roots towards gravity. When the plant stem grows away from gravity it is termed negative geotropism and when plant roots grow towards gravity it is termed positive geotropism. This enables the plant to anchor its roots securely in the ground, reaching water and minerals to ensure their survival and to ensure that the stem grows upright towards the light.

Learning Objectives

To carry out experiments to investigate the e ect of geotropism in plants.

Materials

Germinating bean seeds, moist cotton wool, petri dish, covering lids, and cellotape

Preparation Procedure

1.           Prepare a petri dishes from bottle caps or from bottoms of empty plastic bottles.

2.           Soak bean seeds/maize grains/cow peas in water.

Figure 6.12: The Effects of geotropism.

Activity Procedure

1.           Make two layers of moist cotton wool.

2.           Place the germinating seeds between the two layers of moist cotton wool.

3.           Place the seeds in a petri dishes with their radicals; one facing hor-izontally, one pointing vertically upwards and one pointing vertically downwards.

4.           Cover the petri dish with a lid made from a box or bottle caps.

5.            Place the petri dish on its edge by using cellotape in the dark cardboard.

6.           Leave it for two days and observe the changes.

Results and Conclusion

Plant roots will grow towards gravity, showing a positive response to gravity. The stems will grow away from gravity, thus showing negative geotropism.

Clean Up Procedure

1. Remove all the unwanted materials from the bench.

Notes

Plant stems grow away from gravity a process termed negative geotropism while roots towards gravity is a process termed positive geotropism. Positive geotropism enables plants to anchor its roots in the ground, reaching water and minerals necessary for their survival.