This is an example of the Water Cycle.
Water returning to the Earth from the atmosphere would be precipitation
The organelle malfunctioning in this case is lysosome. They have powerful enzymes and acids to digest and recycle cell material so they remove waste from the cell.
E) All of the answers are correct.
Ion channels are proteins located in the membrane that allow ions to pass through the channel pore. Ion channels can be classified (by what opens and closes the channels) into few groups:
• Voltage-gated channels-open and close in response to membrane potential
Examples: Voltage-gated proton channels, Voltage-gated sodium channels, Voltage-gated potassium channels
• Ligand-gated (neurotransmitter) or ionotropic receptors (ligand binds to extracellular domain of the receptor
Examples: "nicotinic" Acetylcholine receptor, ionotropic glutamate-gated receptors
• Lipid-gated- lipid molecules bind to the transmembrane domain of the channel
Example: Inward-rectifier potassium channels
• Light-gated channels-like rhodopsin channel that is directly opened by photons
• Mechanosensitive (e.g. stretch, pressure) ion channels.
A) The answer is allosteric interaction where activators or repressors bind to a protein, other than the protein active site, hence changing the protein conformation. This interaction occurs between the heme subunits of haemoglobin.
b) Through protonation. The amino group of the alpha subunits and the histidine C-terminal of beta subunits acquire H+ when the blood has low pH. Low pH in the blood is due to accumulation of carbon dioxide and consequent formation of carbonic acid. Protonation of the residues cause allosteric interaction, due to ionic interaction, of the subunits hence resulting to conformation change of haemoglobin between T-state and R-state
