Electron Flow Generates Heat

Biological Strategy

Sacred lotus

AskNature Team

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Transform Thermal Energy

Heat is necessary for survival, but too much of it can be damaging to an organism. Explore the ways different living things have adapted to use or transform different types of thermal energy.

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Send Light Signals in the Non-visible Spectrum

Living systems interact with each other and with their environments to gain information, which is sometimes in the electromagnetic spectrum. Wavelengths of the electromagnetic spectrum are also called the non-visible light spectrum because humans cannot detect them with the naked eye. These include ultraviolet (UV) light, infrared (IR) light, radio waves, and other wavelengths, which living systems can use to send signals. Those signals must not only be targeted to other living systems that can detect them, they must be energy- and material-efficient. This creates both challenges and opportunities. For example, some web-weaving spiders add UV-reflective silk strands to their webs to keep birds and bumblebees (which can see UV light) from crashing into and destroying them. But because the insects the spiders feed on they can’t see UV wavelengths, they fly into the web.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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The sacred lotus attracts pollinators by producing heat through a nonphosphorylating electron transport pathway that releases energy by electron flow through an alternative respiratory pathway.

Image: Coen Boonen / Arno Vlooswijk /

This infrared images combined with a regular image in greyscale shows the warmth produced at the beginning of the openingceremony.

Image: Coen Boonen / Arno Vlooswijk /

This infrared images from a lotus flower, top-down, shows the warmth produced inside the flower while opening. As there was no sunlight during the capturing of the images the warmth is produced by the flower itself.

The alternative pathway of respiration, catalysed by the Alternative
Oxidase (AOX), is responsible for heat production in the sacred lotus (Nelumbo nucifera).

“We report results from in vivo measurements, using oxygen isotope discrimination techniques, of fluxes through the alternative and cytochrome respiratory pathways in thermogenic plant tissue, the floral receptacle of the sacred lotus (Nelumbo nucifera). Fluxes through both pathways were measured in thermoregulating flowers undergoing varying degrees of thermogenesis in response to ambient temperature. Significant increases in alternative pathway flux were found in lotus receptacles with temperatures 16^oC to 20^oC above ambient, but not in those with lesser amounts of heating. Alternative pathway flux in the hottest receptacles was 75% of the total respiratory flux. In contrast, fluxes through the cytochrome pathway did not change significantly during thermogenesis. These data support the hypothesis that increased flux through the alternative pathway is responsible for heating in the lotus and that it is unlikely that uncoupling proteins, which would have produced increased fluxes through the cytochrome pathway, contribute significantly to heating in this tissue. Comparisons of actual flux, with capacity determined using inhibitors, suggested that the alternative pathway was operating at close to maximum capacity in heating tissues of lotus. However, in nonheating tissues the inhibitor data significantly overestimated the alternative pathway flux. This confirms that isotopic measurements are necessary for accurate determination of fluxes through the two pathways.” (Watling et al. 2006:1367)