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>.
<span>microorganisms of different grous are not uniformly susceptible to chemical disinfection due to the level of resistance of the BACTERIA</span>
Answer:
I believe it is A, but I could be wrong.
Explanation:
I think this, because when it says, "Other, less useful, versions of the genetic code were eliminated gradually throughout the course of evolution", I think it referencing to the fact that all animals and etc, are made up of common codes, and how over time, through evolution, certain codes were eliminated, because creatures were evolving.
Answer:
D diffusion across a membrane
Explanation:
Based on whether or not energy input is required, there are two types of processes viz: passive and active. Passive processes are those that do not require energy input in form of ATP while active processes require energy input to occur.
An example of passive process is DIFFUSION, which is the movement of molecules from a region of high concentration to a region of low concentration across a membrane. Diffusion is passive i.e does not require energy, because movement occurs down a concentration gradient.
Other processes in the options like cell division, DNA replication and protein synthesis all require energy input to occur.
