Answer:
The correct answer is None of these choices are correct.
Explanation:
Crossing over doesn't occur only between heterozygous genes, it also doesn't happen only in some chromosomes and it never reduces de variation, otherwise, the crossing over is one of the main causes of variation among species.
1.) Enzymes are a type of protein that speeds up the rate of chemical reactions
2.) Catalase is an enzyme in the liver that hydrogen peroxide (H2O2)
3.) By lowering the activation energy needed
4.) Catalysts
The serotonin binds to a G-protein -coupled receptor and activates a G-subunit . This results in activation of PKA and closing of the potassium channels. This will subsequently decrease the influx of potassium ions into the cell, and lead to depolarization of the cell. This changes the membrane potential of the cell.
Aplysia are sea slugs which fall under the category of mollusks. Serotonin is a hormone which is responsible for the transfer of electrical signals from the brain to different parts. In this particular mollusk, serotonin was studied to find that it is an essential neurotransmitter that is responsible for the maintenance of synaptic plasticity in the neurons. Synaptic plasticity is the feature which is essential for the communication of neurons. This is the modification which occurs at the synapses during the transmission of synapses. Without this activity, the transmission of signals would be impossible.
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When electrons are added to the outermost shell of a carbon atom, it forms an anion that has a larger radius. An anion always has a larger radius than a neutral atom of the same element. This is because more electrons cause greater repulsion between its nucleus and electrons, making the electrons move farther away from the center.