Answer:
<h2>C. placing carrier proteins in the membrane.</h2>
Explanation:
If there is no barrier preventing molecules from moving molecules, then there will be large movement of molecules from an area of high concentration to an area of low concentration. This passive process is known as diffusion. The phospholipid bilayer of a cell's membrane works as a barrier to large molecules, ions, and most hydrophilic molecules. Whereas small hydrophobic molecules can pass freely through the phospholipid bilayer, other molecules and ions are transported across the cell membrane with the help of transport proteins. Some transport proteins, allowing hydrophilic molecules and ions to passively move through them and across the cell membrane.
Examples: carrier proteins and channel proteins.
Placing carrier proteins in the cell membrane will allow the molecule to reach equal concentrations on the both the sides of the membrane and maintain that way over long time. In contrast, transport proteins known as pumps will use cellular energy, usually in the form of ATP, to transport molecules.
Placing equal numbers of intracellularly directed and extracellularly directed pumps would also equalize the concentrations of a molecule long over time. Pumps are to transport molecules against their concentration gradient, such as the sodium-potassium pump continuously moves sodium ions out of a cell.
Through the use of carrier proteins, there is equalization of concentrations of a hydrophilic molecule. This equalize the numbers of molecules on the inside and outside of the cell, but the pumps would continue moving the molecule inward, eventually resulting in more molecules inside of the cell than out.
tree and nest
If a robin builds a nest in a big tree, the robin benefits and the tree
is not helped or harmed. This type of symbiotic relationship is called
commensalism, and it is between the tree and the nest/Robin.
<span>There are several types of biotic relationships that is occurring every single moment in the ecosystem and commensalism is one. In contrast, parasitism is the biotic relationship where one organism doesn't benefit from the other and is harmed. In this scenario with human beings and mosquitos, this phenomenon of interaction is distinguished as parasitism where mosquitos draws blood that contains nutrients from the human tissue to use it as its source of food and then leaves harmful substances and bacteria in the human’s blood stream.<span> </span></span>
Mammals do; I'm in my science class
