Answer:
The process of passage of different molecules, solutes, and liquids, through the phospholipid bilayer in human cells, and really in all animal cells, is highly dependent on a tight coordination between chemical, and thermodynamic balances, that will collaborate in these elements being able to pass, or not pass, through a cell´s membrane, and activate other mechanisms within the cell when their passage is not possible. Unlike what was once believed, that transport proteins were like buses parked at the membrane and waiting to be loaded with molecules to later remove themselves from the membrane and carry their load into the cytoplasm, scientific research has found that this is definitely so, and that transport proteins do not come off the layer to transport molecules. They are permanently anchored to the membrane and through a series of second messenger systems, energy produced by the passage of certain ions like potassium and sodium, and other such processes, these transport proteins become activated, allow the passage of molecules and change them in such a way that they can be taken into the cell in vesicles, or, they will anchor them to second messengers, who will be responsible for carrying the molecule inside.
From the list of words given and the two sentences down below, which are two reasons why the earlier believed models for transport proteins are not correct would be:
1. Integral membrane proteins are embedded stably in the membrane and protrude from one or both side based on their hydrophobic, or hydrophilic, regions. These sides will not switch because of the disbalance that would be created if the two sides had to be switched chemically to allow them to pass to the opposie sides.
2. For protein to traverse a membrane, movement of its hydrophilic regions through the interior of the membrane would be required, which would be highly endergonic and hence thermodynamically improbable.
Answer:
The characteristic of water that makes this liquid stick to the side of a test tube is called capillarity (Claim).
Explanation:
Water (H₂O) is a polar molecule with the ability to generate van der Waals forces, which is explained by the 4 hydrogen bonds it forms to bind to other substances. The consequence of the forces of the molecular bonds are four properties of H₂O, including surface tension, cohesion, adhesion and capillarity.
- <u>Claim</u>: The characteristic of water that makes this liquid stick to the side of a test tube is called capillarity.
- <u>Evidence</u>: Cohesion and adhesion of water are properties that come from the forces of the molecular bonds of water, and whose effect is the ability of water to wet surfaces and adhere to a tube that contains it, the latter due to capillarity. Capillarity also allows water to rise through the roots and stems of plants, through their thin vascular ducts.
- <u>Reasoning</u>: <u>cohesion</u> in water depends on the force of attraction between H₂O molecules, <u>adhesion</u> is the capacity of H₂O molecules to join other different molecules and —together with <u>surface tension</u>— make H₂O molecules close to the walls of a glass tube adhere to it, which represents capillarity.
The effect of capillarity is more evident when the test tube is of a smaller diameter, although capillarity and adhesion to its walls always exist, and to a greater degree than any other substance.
Answer: It is because it makes it more efficient to study organisms.
Explanation: Biologist classify organisms by considering similarities between them. The organisms which have closely related characteristics are placed in a separate domains by biologists. Domains are further divided into 6 Kingdoms. According to modern classification system, domain is largest unit of biological classification.
