Answer:
b. a semi-permeable double layer of phospholipids that have hydrophilic heads and hydrophobic tails
Explanation:
B is correct as the cell membrane is selectively semi-permeable. It is selectively semi-permeable because this quality allows it to control what can and can't enter the cell, and how it does so.
The cell membrane also has a phospholipid bi-layer comprised of a double layer of phospholipids which have hydrophilic head and hydrophobic tails. This is because the heads are made of phosphate and are polar and are therefore attracted to water (hydrophilic), while the tails are made of lipids (i.e. fats, oils) which do not mix with water and are therefore hydrophobic.
The properties of each phospholipid is also why they form the double layer structure, the hydrophilic heads naturally face outwards into the water and protect the hydrophobic tails on the inside.
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The carbon cycle:
The carbon cycle is the process in which carbon travels from the atmosphere into organisms and the Earth and then back into the atmosphere. Plants take carbon dioxide from the air and use it to make food. Animals then eat the food and carbon is stored in their bodies or released as CO2 through respiration.
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Answer:
Gated ion-channels
Explanation:
These ion channels are protein molecules that act as a passageway which span across the cell membrane allowing the movement of ions from one side of the membrane to the other. They possess the ability to open and close in response to either chemical or mechanical signals.They possess a fluidic pore, which becomes available to ions after a conformational change in the protein structure has been activated causing the ion channel to open. Based on the stimulus to which they respond, ion channels are divided into three groups: voltage-gated, ligand-gated and mechano-sensitive ion channels. Channels responding to electrical (voltage-dependent ion channels), mechanical, or chemical (ligand-gated ion channels) stimuli open and allow rapid ion movement into or out of the cell, and this movement creates an electrical signals.
D,E,G is the correct answer
Answer:
C. The high concentration of hydrogen ions in the intermembrane
Explanation:
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