Take two glass jars and fill them with water. Now, take two onion bulbs and place one on each jar, as shown in the figure given below.
Length - Jar 1, Jar 2
Day 1 - 3 cm, 3 cm
Day 2 - 3.5 cm, 3.5 cm
Day 3 - 4 cm, 4 cm
Day 4 - 4.5 cm, 4.5 cm
Day 5 - 5 cm, 3.5 cm
Day 6 - 5.2 cm, 3.5 cm
Day 7 - 5.4 cm, 3.5 cm
Observe the growth of roots in both the bulbs for a few days.
Measure the length of roots on day 1, 2 and 3.
On day 4, cut the root tips of the onion bulb in jar 2 by about 1cm. After this, observe the growth of roots in both the jars and measure their lengths each day for five more days and record the observations in tables, like the table
From the above observations, answer the following questions:
(a) Which of the two onions has longer roots? Why?
(b) Do the roots continue growing even after we have removed their tips?
(c) Why would tips stop growing in jar 2 after we cut them?
(a) The onion in jar 1 has longer roots, as the growth of roots continues in it due to intact root tips.
(b) The roots did not continue to grow in jar 2 after cutting down their tips.