Nutrition

Aconitum napellus gets its food through the process of photosynthesis, or the conversion of light energy to chemical energy.

The light reactions occur within the thylakoids of the chloroplasts found in the plant leaf cells. Photosynthesis is divided into two main processes, the light and the dark reactions. In these thylakoids there are specialized pigment molecules, the most important of which is called chlorophyll and these pigment molecules are inside a structure called a photosystem. Light enters these photosystem structures and excites the chlorophyll pigments, once excited the chlorophyll gives up electrons to an area in the photosystem called the primary electron acceptor. These high energy electrons are then passed down through a chain of proteins called the electron transport chain, slowly losing energy with each successive transfer.  Eventually the electrons end up being transferred to the special “shipping” molecule known as NADPH. The electrons lost by the chlorophyll are replaced by water molecules. The transfer of electrons to NADPH marks the start of the dark reactions, or the Calvin cycle.

In the Calvin cycle the ATP and NADPH generated from the light reactions is used up to help bind carbon dioxide molecules together into a 3- carbon structure called G3P. This is done through a series of oxidation-reduction reactions which makes and breaks bonds as the carbon molecules change forms. G3P is the precursor to most sugars! The sugar can then be either transported, stored, or broken back down into ATP for the cells to use. In A. napellus, is most of the sugar is either broken down to give the plant energy for growth, but otherwise it is stored down in the roots.

The water that the plant needs to grow and photosynthesize is taken up through the roots from the soil.

The water and sugar is transported through the plant in specialized tissues called xylem and phloem. To read more about these unique transport tissues and how they work click on the link here. It is important to recognize that plants can only perform photosynthesis once they have grown leaves. In the short stage in the plant’s early life when it is still covered by the soil it actually is classified as being heterotrophic. This young plant gets its nutrients from special tissue found within its seed. This tissue is called endosperm and it takes up a large portion of the inside of the seed. Endosperm is made of energy rich materials, and it gives the plant just enough of a boost to be able to grow out of the soil and make leaves. To read more about the adaptation of endosperm click here.

Autotrophs like A. napellus are extremely important in bringing energy into ecosystems. The photosynthesis performed by plants is what makes it possible for organisms as big as us to have evolved!

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