Difference Between Autonomic and Paratonic Movements

The key difference between autonomic and paratonic movements is that autonomic movements are the responses to a stimulus generated within the plant due to genes while paratonic movements are the responses of plants to an external stimulus without the involvement of genes.

Plants respond to external stimuli; they also respond to the stimuli generated within the plant. Based on that, there are two types of movements as autonomic movements and paratonic movements. Autonomic movements are the responses exhibited to some internal causes, especially due to the involvement of genes. In contrast, paratonic movements are the responses exhibited to external stimuli such as heat, pressure, water, sunlight, etc. Due to the involvement of genes, autonomic movements are present in plants by birth, unlike paratonic movements.

CONTENTS

1. Overview and Key Difference
2. What are Autonomic Movements
3. What are Paratonic Movements
4. Similarities Between Autonomic and Paratonic Movements
5. Side by Side Comparison – Autonomic vs Paratonic Movements in Tabular Form
6. Summary

What are Autonomic Movements?

Autonomic movements are the responses plants show to internal stimuli. These movements are spontaneous. They arise automatically due to internal causes, especially due to genes. Autonomic movements can be seen clearly in unicellular organisms as well.

Flagellar movement in Chlamydomonas is an autonomic movement. Other examples of autonomic movements are beating of cilia and flagella, protoplasmic streaming, circumnutation, and the movement of chromosomes during nuclear division.

What are Paratonic Movements?

Paratonic movements are the responses exhibited by plants to external stimuli such as sunlight, gravity, water, chemicals, temperature, and turgor. There are several types of paratonic movements: taxes, tropic movements and nastic movements, etc. Plant shoots elongate towards the sunlight. Thus, this is a paratonic movement that is phototropic. Similarly, plant roots grow towards the soil. This is another paratonic movement which is geotropic. Likewise, paratonic movements arise due to external stimuli.

Some paratonic movements are directional while some are non-directional. Moreover, tropic movements are directional, while nastic movements are non-directional.

What are the Similarities Between Autonomic and Paratonic Movements?

• Autonomic and paratonic movements take place as a response to a stimulus.
• Plants show both autonomic and paratonic movements.
• Moreover, they are important movements of plants and in some unicellular organisms.

What is the Difference Between Autonomic and Paratonic Movements?

Autonomic and paratonic movements are two types of movements exhibited mainly by plants. Autonomic movements are the responses to the internal causes, while paratonic movements are the responses to the external stimuli. Therefore, this is the key difference between autonomic and paratonic movements. Furthermore, autonomic movements are present at birth since genes regulate them; however, paratonic movements are not present at birth since external stimuli induce them. So, this too is a significant difference between autonomic and paratonic movements.

The below infographic summarizes the difference between autonomic and paratonic movements.

Summary – Autonomic vs Paratonic Movements

Autonomic movements take place due to internal stimuli, while paratonic movements take place due to external stimuli. So, this is the key difference between autonomic and paratonic movements. Moreover, genes play an important role in autonomic movements, while genes do not participate in paratonic movements.

Reference:

1. G.R. Kantharaj, “Physiology of Plant Movements”, Plant Cell Biology, Available here.

Image Courtesy:

1. “Flagellum-beating” By Original:UnknownVector:Urutseg – File:Flagellum-beating.png (CC BY 3.0) via Commons Wikimedia
2. “Phototropic Zinnia” By Bart Everson  (CC BY 2.0) via Flickr