CLIFF NOTES

Forced to adapt to modern times, plants now have specialized systems to utilize the relatively low concentration of atmospheric CO2, around 0.036% or 360ppm.

As the sun sets, the wavelength of light generated by the sun shifts from blue to red.

prepare themselves for sunrise and photosynthesis. Essentially, they carry out cyclic processes known as a circadian rhythm, from Latin meaning â??approximately a day.â?

Oxygen is the magical energy transporter in all forms of aerobic respiration,

the leaf are most prevalent because they are the primary site of light absorption, sugar formation, and gas exchange. During the night, stomates in the leaf are nearly closed as the need for gas exchange is small and to prevent unnecessary water loss. During the day when photosynthesis is in full swing, the demand for CO2 uptake is great and stomata are wide open. Unfortunately, high temperatures increase water loss through the same stomatal openings that are trying to uptake CO2. Therefore, photosynthesis is both temperature and light dependent as an increase in temperature reduces the amount of carbon that is fixed, or carboxylated, into sugar by the Calvin Cycle. Photosynthesis reaches a maximum rate at a temperature of 30°C (85ºF) and remains efficient ± 5°C (75-95ºF).

many stomata are dedicated to CO2 uptake rather than water transpiration. This factor is known as the Transpiration Ratio.


Temperature has a direct affect on the transpiration ratio. Not only does heat induce water loss through stomata, an increase in temperature also reduces the concentration of dissolved CO2 in air,

CO2 during the light cycle when stomata are open and gas exchange is readily occurring. Simply doubling the ambient concentration to 700ppm will increase the photosynthetic rate by 30-60%.

During the dark cycle, plants undergo aerobic respiration. Respiration is divided into three parts: Glycolysis, the Kreb or Citric Acid cycle (TCA), and the Electron Transport Chain.


Red light plays an important role in the regulation of the dark cycle. Red light is the color of the rising and setting sun. Plants temporally govern most biochemical processes by a circadian rhythm, a type of internal biological clock.

The flowering response has been determined to be a result of the length of darkness a plant receives.


Regulation of a plantâ??s energy metabolizing systems function on many levels. A biochemical pathway can only proceed as fast as the rate limiting enzyme or substrate. The primary source of regulation is genetic. Chloroplasts and mitochondria have their own genetic code that produce the enzymes needed for their respective process. The only way to up-regulate genetic expression is either through genetic engineering or producing more of these genes by making sure the plant has all its required nutrients to produce more new cells

Changes in water properties, nutrient availability, temperature, light duration and strength, humidity, and dissolved gas concentrations are big obstacles that need to be orchestrated to achieve maximal metabolic activity.


As one can see, plants are definitely not getting a restful sleep at night