Physio

To be more specific, what is transpiration in plants?

The special reference to plants should be proper and is not without basis. It is because this process is not exclusive to plants.

It also occurs in mushrooms.

This paper and its component pages relate to the kingdom Plantae.

The word is the noun ‘transpire‘ from Latin trans, meaning across or through, and spirare or breathe.

It is the natural process by which liquid water within the plant is converted to gas and, in this state of matter, lost via various aerial organs but primarily through the leaves.

Stated simply, it is the evaporation of water from plants.

Stephen Hales (1677-1761) referred to it as perspiration.

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This is a partial account of the history of photosynthesis.

It covers the period from 1648 when Johann Baptista van Helmont’s Ortus Medicinae was published until about 1900 when the issue on the use of the term ‘photosynthesis’ finally subsided.

The telling is done by way of revisiting the works of selected contributors.

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What is photosynthesis?

Photosynthesis literally means synthesis (or manufacturing) with light.

It is the physiological process occurring in plants by which carbon dioxide (CO₂) and water (H₂O), in the presence of visible light and chlorophyll, are converted to organic compounds which store chemical energy.

It also occurs in other chlorophyll-containing organisms such as algae and cyanobacteria.

In 1993, Howard Gest of Indiana University gave the following definition of photosynthesis: Photosynthesis is a series of processes in which electromagnetic energy is converted to chemical energy used for biosynthesis of organic cell materials; a photosynthetic organism is one in which a major fraction of the energy required for cellular synthesis is supplied by light(Gest 2002).

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What is sugar?

Sweetness is always the first thing that comes to mind in responding to the question or in contemplating what is sugar.

In ordinary usage, sugar is the common term for sucrose, those brownish granules or fine white crystals that bear the name brown sugar or refined sugar with which coffee, milk, and other drinks are sweetened.

Being processed from raw materials, it is likewise described as an industrial product with varied uses, particularly in food science including as a preservative.

In studying basic physiology in plants, sugar is commonly used interchangeably with carbohydrates.

Both words are used to refer to the product of photosynthesis which stores the energy obtained from the sun and the carbon fixed from the atmosphere.

However, sugars are only a subset of carbohydrates. The question What is sugar? therefore ought to settle on what is carbohydrate.

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There are three distinct biochemical variants or types of photosynthesis based on the mechanism that plants employ by which carbohydrate is formed from CO2: C3 photosynthesis, C4 photosynthesis, and CAM photosynthesis.

The table below shows their respective features.

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