Structural Composition Provides Strength in Changing Conditions

Biological Strategy

Plants

AskNature Team

Image: Anatoly Mikhaltsov / Wikimedia Commons / CC BY SA - Creative Commons Attribution + ShareAlike

Manage Compression

When a living system is under compression, there is a force pushing on it, like a chair with a person sitting on it. When evenly applied to all sides of a living system, compression results in decreased volume. When applied on two sides, it results in deformation, such as when pushing on two sides of a balloon. This deformation can be temporary or permanent. Because living systems must retain their most efficient form, they must ensure that any deformation is temporary. Managing compression also provides an opportunity to lessen the effects of other forces. Living systems have strategies to help prevent compression or recover from it, while maintaining function. For example, African elephant adults weigh from 4,700 to 6,048 kilograms. Because they must hold all of that weight on their four feet, the tissues of their feet have features that enable compression to absorb and distribute forces.

Search this Function

Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

Search this Function

Plants

Phylum Plantae (“plants”): Angiosperms, gymnosperms, green algae, and more

Plants have evolved by using special structures within their cells to harness energy directly from sunlight. There are currently over 350,000 known species of plants which include angiosperms (flowering trees and plants), gymnosperms (conifers, Gingkos, and others), ferns, hornworts, liverworts, mosses, and green algae. While most get energy through the process of photosynthesis, some are partially carnivores, feeding on the bodies of insects, and others are plant parasites, feeding entirely off of other plants. Plants reproduce through fruits, seeds, spores, and even asexually. They evolved around 500 million years ago and can now be found on every continent worldwide.

Search this Living System

The cell walls of vascular plants provide mechanical strength during different stages of growth by adjusting their structural composition.

Image: LadyofHats /

Diagram of the plant cell, with the cell wall in green.

Image: Orange Coast College Biology Department (Marc Perkins) /

Cross section through a Ficus leaf, seen at approximately 40x magnification. Ficus leaves have sunken stomates, meaning that their guard cells are not on the outer surface of the leaf, but instead embedded a few cell layers inside the leaf.

“Plant cells need to be fully hydrated to work properly (except in periods of dormancy, as for example in many seeds). Individual vegetative cells in plants, unlike those in animals, are encased in a cell wall. The cellulose cell wall may be very thin, in cells that are actively dividing, as for example, in growing shoot or root tips. However, once developed into their mature form, the cell walls may become thicker, and additional substances, mainly lignins, incorporated into their structure. The cells themselves, then, contribute to the mechanical strength of the plant. Thin-walled cells when fully hydrated, are like small, pressurised containers. Mature cells, especially those with thick walls, have mechanical strength of their own, even without watery contents. Indeed, many fibres lack living contents when mature.” (Cutler 2005:98)

Last Updated September 14, 2016

References

“Plant cells need to be fully hydrated to work properly (except in periods of dormancy, as for example in many seeds). Individual vegetative cells in plants, unlike those in animals, are encased in a cellulose cell wall. The cellulose cell wall may be very thin, in cells that are actively dividing, as for example, in growing shoot or root tips. However, once developed into their mature form, the cell walls may become thicker, and additional substances, mainly lignins, incorporated into their structure. The cells themselves, then, contribute to the mechanical strength of the plant. Thin-walled cells when fully hydrated, are like small, pressurised containers. Mature cells, especially those with thick walls, have mechanical strength of their own, even without watery contents. Indeed, many fibres lack living contents when mature.” (Cutler 2005:98)

Book section

Nature in Design [Chapter title: Design in Plants]

WIT Press | M. W. Collins (Author, Editor), M. A. Atherton (Editor), J. A. Bryant (Editor) [Chapter author: Cutler, DF]

embedly preview

AskNature