Student(s):Ana Azinović, Lara Krkanić, Petra Zovko
Grade Level:Secondary School (grades 9-12, ages 14-18)
GLOBE Teacher(s):Mirjana Krpan
Report Type(s):Standard Research Report
Protocols:Dissolved Oxygen, Nitrates, Water Temperature
Date Submitted:12/27/2019

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The aim of this project was to determine the differences in water quality from different
stations and their influence on changes in mitosis and on the number and growth intensity of
Allium cepa L. roots. We determined the pH of water, dissolved oxygen, nitrate, nitrite,
ammonia and phosphate ions. In this project, we have proved our assumption that there are
differences in water quality in physical and chemical parameters between tap water, water
from Jelenovac stream, lakes Jarun and Bundek and the Sava River. For each sample of
water, five bulbs were placed in the examined water with their basal parts. After 14 days the
roots were counted and measured. By microscopic observation of the root tips sections were
determined mitosis phases and we calculated the mitotic index. Chromosomal abnormalities
were also evaluated. Root lenghts were smaller in water having lower quality. The
contaminated water caused decreased mitotic activity and increased the occurrence of
chromosomal aberrations in the root cells. The project has shown slow growth of root tips
and the smallest number of roots in the water of the Sava River. According to the measured
physico-chemical parameters, the water from the Sava River was the most polluted, the
mitotic index was the smallest and the number of aberrations was the greatest.


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