Take two glass jars and fill them with water. Now, take two onion bulbs and place one on each jar. Observe the growth of roots in both the bulbs for a few days. Measure the length of roots on 1st, 2nd and 3th day. On day 4 cut the root tips of the onion bulb in jar 2 by about 1 cm. After this, observe the growth of root in both the jars and measure their lengths each day for 7 days. Record the observation in a table as:plot a graph based on your observations and derive the conclusion.
Answers
At first, the roots in the first jar will comprise longer roots.
Besides, root tips comprises of meristematic tissue therefore, cutting them affect the growth of the plant .
On the other hand, the roots comprises of meristematic tissues, hence, cutting them would disturb the growth process of the plant.
Answer:
At first, the roots in the first jar will compromise longer roots. Besides, roots tips comprises of meristematic tissue therefore, cutting them affect the growth of the plant. On the other hand ,the roots comprises of meristematic tissues, hence, cutting them would disturb the growth process of the plant.
Explanation:
- Take two glass jars and fill them with water.
- Now, take two onion bulbs and place one on each jar, as shown in Fig.
Fig.: Growth of roots in onion bulbs
The figure shows 2 glass jars; jar 1 & jar 2, filled with water. Both the jars have a onion bulb half submerged in water. Roots are growing in both the onion bulbs.
- 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:
(a)The growth of plants occurs only in certain specific regions. This is because the dividing tissue, also known as meristematic tissue, is located only at these points. Depending on the region where they are present, meristematic tissues are classified as apical, lateral and intercalary . New cells produced by meristem are initially like those of meristem itself, but as they grow and mature, their characteristics slowly change and they become differentiated as components of other tissues. 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. Apical meristem is present at the growing tips of stems and roots and increases the length of the stem and the root. The girth of the stem or root increases due to lateral meristem (cambium). Intercalary meristem seen in some plants is located near the node.
(c) The tips of root stopped growing in jar 2 because the tips of these roots were cut down and the tissues which helps in the growth of roots i.e., meristematic tissues are removed from it.
Cells of meristematic tissue are very active; they have dense cytoplasm, thin cellulose walls and prominent nuclei. They lack vacuoles.
Learn about the concept
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