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:I think it is part B
Explanation:
Kelp --> sea urchins ---> sea otters best represents the feeding relationships in a kelp ecosystem that has not been disturbed
by humans.
Answer:
D. Each enzyme can catalyze a wide variety of different reactions
Explanation:
Each enzyme can only catalyze a few, specific types of reactions.
Since enzymes and substrates are very specific to one another, enzymes cannot catalyze a wide variety of reactions.
If a substrate is not the correct one that fits in the enzyme's active site, a reaction will not occur.
So, each enzyme can only assist in a few reactions.
The correct answer is D. Each enzyme can catalyze a wide variety of different reactions