The answer here is D, and it's kind of obvious. But you probably already knew the answer and are just doing this for piece of mind.
Explanation: Just the fact that we don't know whether or not there even is extraterrestrial life rules out every other answer, without even needing to go in depth.
(Okay, I read your question completely wrong, it's asking for which one of these has been solved isn't it?)
This is tough because all of these other than D have been figured out. Go with the methane atmosphere then.
Answer: Vascular smooth muscle cells.
Explanation:
Vascular smooth muscle cells are the contractile tissues which regulates flow blood and pressure of the blood by vasoconstriction (contraction) and/or vasodilatation (relaxation).
Vasoconstriction is the contraction of the blood vessels to increase tge pressure of the blood.
Vasodilatation is the relaxation of the blood vessels which results in a decrease in blood pressure.
Answer:
Resting potential
Explanation:
This is because , the resting potential is negative in side of the cell because it has more negative charge inside than outside due to accumulation of alot of sodium and potassium ions. when an axon is at rest in the cell, the anions produce negative charge, the sodium pumps eject sodium out of the cell and potassium is injected in, and the sodium gates and potassium gates are all closed.
4. promoting tissue growth in body cells
Answer:
Unlike typical mammalian red blood cells, those from amphibians, such as frogs, contain a DNA-bearing nucleus that is visible in the center of the cell. The circulatory system of amphibians is rather unusual, their hearts having three chambers, two atria, and a single ventricle.
NegativePositive
Positive
The design of the amphibian circulatory system is curious because blood accumulates oxygen in the lungs and is then returned to the heart before being pumped into the rest of the circulatory system. Therefore, a mixing between oxygenated and deoxygenated blood occurs as blood returning to the heart from the lungs is mixed with incoming blood from the body. Frogs handle this situation by having a very slow metabolism and by absorbing some oxygen through their skin. In addition, the ventricle does have some directional control over the distribution of the blood.
Negative
The presence of a nucleus in amphibian red blood cells allows researchers easy access to large quantities of amphibian DNA. Frog blood has both a solid and a liquid portion. The liquid plasma carries solid elements such as red and white blood cells. Blood can be collected from frogs and the red blood cells isolated by centrifugation. After removal of the residual plasma, purified cells can be treated with specific enzymes and detergents to digest the cellular envelope and release DNA from its protein complex. The DNA is then useful for scientific studies and experiments.
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Explanation:
