Answer:
Most preservation methods cannot completely eliminate spoilage phenomena indefinitely.
Explanation:
There are many different types of preservation methods. They inclue things like dehydration, smoking, fermentation, salting, sweetening, canning, freezing, ultra high temperature, and irradation. Although some of these change food integrity, others maintain it. However, no method of preservation can preserve food indefinitely.
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MHC I class of molecules appears on the cell surface of all nucleated cells and those cells are n<span>on-professional antigen presenting cells</span>. Their function is to present an antigen to cytotoxic T cells (T lymphocytes). After a viral or bacterial infection, MHC I molecules will present those foreign proteins on the surface and T cells specific for the MHC will recognize and kill presenting cell.
Answer:
The correct statement concerning the cell membrane lipid molecules is that "energy is not expended during diffusion" (Option d)
Explanation:
Biological membranes are formed by two lipidic layers arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, and their hydrophobic tails against each other. Membranes are fluid, which means that molecules that form it have the capability to move through it.
Lipids can easily change places with other neighbor lipids by <u>lateral diffusion</u> in the same layer. This is passive diffusion, which means that it does not need energy to happen.
Lipids can also diffuse transversally to the other layer, but this kind of movement is not as easy as lateral diffusion.
There are also other lipidic movements as rotational diffusion that imply the rotation of the molecule.
Through this lipidic bilayer, there is also a passive transport of some particles from one side of the cell to the other which happens because of concentration differences.