Are responsible for the structures and functions of organisms.

The right answer is proteins.

Protein functions are very varied and are used as a basis for classification.

There are several groups:

* Enzymatic proteins: any protein catalyzing biological reactions Antibodies: defense proteins

* Transport proteins (molecules, or various ions): we can mention myoglobin and hemoglobin, which are capable of binding reversibly oxygen, but also blood lipid transporters, membrane transporters ( pump type, channels ...)

* Regulatory proteins: they participate in the regulation of extremely diverse cellular or physiological processes. We can mention: protein hormones, all the receptors and proteins associated with these receptors, the proteins involved in cellular transduction phenomena, all the proteins involved in the control of gene expression ...

* Contractile proteins: involved in cell motions. We can mention: actin, myosin, tubulin

* Reserve proteins: serve as reserve amino acids, stored massively at a period of development then are used and hydrolyzed massively at another stage of development: ovalbumin of eggs, grains of aleurones in the albumen seeds (which contain gluten in wheat ...)

* Architectural proteins, which participate in the construction and maintenance of cell and tissue structures, but also participate in the protection of certain types of cells: keratin, collagen, fibroin (spider webs) ...

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.