Answer:
<u>d. Transport proteins within the membrane serve as a tunnel for molecules to enter the cell.
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Explanation:
Solutes are typically moved across the cell through either passive or active transport. The cells, surrounded by a bilipid layer or plasma membrane is amphiphlic- its polar, hydrophilic lipid heads face outwards, while their non-polar hydrophobic lipid tails face inwards towards each other.
While lipid-soluble molecules move across the layer easily, it is also difficult for charged and also large molecules to move across its surface, into the cell. Transmembrane channels, <u>embedded within the membrane</u>, help to maintain selective permeability as transport proteins, pores and gated channels. Simple diffusion happens as a method of passive transport in cells through plasma membranes.
The solutes travel through the plasma membrane in the process of diffusion from regions of high concentration to regions of low concentration; this occurs without the use of energy. <u>Molecules moving against their concentration require active transport mechanism to cross the membrane</u>.
A dwarf is a recessive trait. In order for the plant to be shorter, it would have to have 2 recessive alleles. The plant is also purebread so it wont contain the tall allele. The gametes that are possible are tt.
I would say the food availability for gray squirrels will be affected because we do not know their diet. It also say that the red squirrels and the black squirrels have the same diets meaning less food on the Island for the grey squirrel( depending on what he eats. )
Answer: (<u>Note</u>: You will find the image with the highlighted structure in the attached file)
Peyer's patches (aggregated lymphoid nodules)
Explanation:
Peyer's patches are anatomical regions located under the mucosa of the gastrointestinal tract, specifically in the lamina propria of the thin intestine. These patches are nodules or cumulus of lymphatic tissue and other accessory cells, and this is why they represent a huge part of the mucosa´s immunity system.
Peyer's patches belong to the group of lymphoid tissue associated with the intestine, composed of lymphoid follicles distributed along the gastrointestinal tract.
A lymphoid follicle is a cumulus or aggregate of lymphoid cells that do not have a well-defined structure nor organization. In general, these follicles are isolated from each other in the intestine. But in the terminal ileum (The last portion of the thin intestine) they get so close that they might form a plaque. The Peyer´s patches are formed principally by lymphocytes B that synthesize immunoglobulin A, which has an important role in immunity.
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