1. Complete Activity 6.1 (Page 61).
• Take two glass jars and fill them with water.
• Now, take two onion bulbs and place one on each jar, as shown in Fig. 6.1.
• 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 1 cm. 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 below:
| Length | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 |
| Jar 1 | |||||
| Jar 2 |
• From the above observations, answer the following questions:
1. Which of the two onions has longer roots? Why?
2. Do the roots continue growing even after we have removed their tips?
3. Why would the tips stop growing in jar 2 after we cut them?
Answer:
Aim: To observe the growth of the roots in the two onions and conclude based that on that.
Materials Required: Two glass jars, water, two onion bulbs.
Procedure:
(i) The two glass jars are filled with water.
(ii) One onion bulb is placed on each jar such that the roots are submerged in water.
(iii) The growth of the roots of the two bulbs is observed for a few days and the length of the roots is measured on day 1, 2 and 3.
(iv) On day 4, the root tips of the onion bulb in jar 2 are cut by about 1 cm.
(v) After this, the growth of roots in both the jars is observed and their lengths each day are measured for five more days. The observations are recorded in a table.
Observations:
| Length | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 | Day 8 |
| Jar 1 | 1 cm | 2 cm | 3 cm | 4 cm | 5 cm | 6 cm | 7 cm | 8 cm |
| Jar 2 | 1 cm | 2 cm | 3 cm | 3 cm | 3 cm | 3 cm | 3 cm | 3 cm |
- Onion in Jar 1 has longer roots.
- The roots do not continue growing in Jar 2 after their tips have been removed.
Conclusions: Apical meristematic tissue is located at the growing tip of roots and is responsible for growth of roots. When the root tips of the onion bulb in Jar 2 were cut, the apical meristematic tissue was removed and hence growth did not take place.
“Take two glass jars and fill them with water.
• Now, take two onion bulbs and place one on each jar, as shown in Fig. 6.1.
• 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 1 cm. 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 below:
| Length | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 |
| Jar 1 | |||||
| Jar 2 |
• From the above observations, answer the following questions:
1. Which of the two onions has longer roots? Why?
2. Do the roots continue growing even after we have removed their tips?
3. Why would the tips stop growing in jar 2 after we cut them?” – Solved.
Related Links:
Solution to Activity 6.1
Solution to Activity 6.2
Solution to Activity 6.3
Solution to Activity 6.4
Solution to Activity 6.5
Solutions to Chapter 6 Tissues
