EXERCISE NO. 4

Question 1

Title of Exercise 4

Answer 1

DEFENSE MECHANISM IN PLANTS:
Adventitious Root formation in Response to Indole-3-acetic acid (IAA)

Question 2

Roots may form from ____ or _____ tissues.

Answer 2

Root - Lateral roots
Stem - Adventitious roots

Question 3

_______ serve several important functions for plants and are crucial for their growth, survival, and adaptation to changing environments.

Answer 3

Roots

Question 4

The ability to cause _________ to form on stems is extremely useful in the production of plant clones for commerce, industry, and research.

Answer 4

adventitious roots

Question 5

If one can produce roots on a stem cutting, then it is possible to make as large a clone as desired. As one takes cuttings from the “mother” plant, it branches due to loss of _______ _________, and provides even more cuttings.

Answer 5

apical dominance

Question 6

function to coordinate plant growth and development

Answer 6

Phytohormones

Question 7

example of growth hormones used is _____________ which is an _________

Answer 7

indole-3-acetic acid or auxin

Question 8

are found in shoot and root tips and promote cell division, stem and root growth.

They can also drastically affect plant orientation by promoting cell division to one side of the plant in response to sunlight and gravity.

Answer 8

auxin

Question 9

• influence the behavior of cells according to their preexisting identity.
• is one such growth coordinator—regulating where, when, how much, and what sort of growth should occur.

Answer 9

Auxins

Question 10

plant used for the expirement

Answer 10

mung bean (Vignata radiata)

Question 11

what are the 4 set ups?

Answer 11

1- 3ml control (distilled water)
2- 3ml 0.01% IAA
3- 3ml 0.001% IAA
4- 3ml 0.0001% IAA

(3 replicates each set-up)

Question 12

What do you need to make sure when you let it stand under the light for a week?

Answer 12

Make sure that the tubes will not run dry by checking daily and adding equal volumes of IAA of the respective solution

Question 13

what are the two things that are needed to be observed

Answer 13

stem growth and number of adventitious roots

Question 14

Which concentrations of IAA produces the most number of roots?

Answer 14

.0001% IAA

Question 15

Which concentrations of IAA produces the least number of roots?

Answer 15

.01%

Question 16

How does IAA influence root formation?

Answer 16

IAA positively influences root formation by promoting cell elongation and division in the root tip, which results in the initiation and growth of new roots. Also helps in, direct root growth in response to gravity (gravitropism).

However, growth regulators such as the IAA can still inhibit growth through phytotoxicity depending on excessive use and timing

Question 17

How does IAA influence stem growth?

Answer 17

at low concentrations (0.0001% IAA) primarily promotes cell elongation. It helps stimulate the expansion of cells in the stem, leading to increased stem length. It softens the cell walls in the stem, making them more flexible and allowing the cells to stretch. This results in increased stem length. Moderate concentrations of IAA (0.001% IAA) continue to promote cell elongation, contributing to stem growth.

Meanwhile, High concentrations of IAA (0.01% IAA) can have inhibitory effects on stem growth. Excessive IAA can disrupt normal growth processes and lead to stunted or abnormal stem development. It should be noted that growth regulators in excessive concentrations or improper typing can result in phytotoxicity

Question 18

How is IAA different from Gibberellins and ethylene in terms of functions?

Answer 18

These three hormones play roles in regulating plant growth and development

IAA is primarily involved in
- promoting cell elongation
- phototropism (growth toward light)
- apical dominance (regulation of lateral bud growth),
- root development.

Gibberellin
- stimulates stem elongation and seed-related processes,

Ethylene
- involved in various growth and stress responses