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>.
Answer:
1 : to institute (something, such as a law) permanently by enactment or agreement. 2 obsolete : settle sense 7. 3a : to make firm or stable. b : to introduce and cause to grow and multiply establish grass on pasturelands.
Answer:
The answer is A.
Explanation:
To test if the selenium from the mine has an effect on the fish living in the lake which i assume is close to the mine, testing the tissue of the fish from that lake and comparing it to the selenium levels of the fish from a nearby lake would be a testable hypothesis because there is a comparable aspect and there should be a difference in the numbers between the fish from the two lakes because of their distance to the mine.
I hope this answer helps.
