Answer:
Mitosis may be defined as the process of cell division in which a single diploid parent cell divides into two daughter cells. The four stages of mitosis are prophase, metaphase, anaphase and telophase.
The chromosomes get align at metaphase plate during metaphase. Sometimes the arrangement of chromosomes takes more time and after their alignment anaphase process begins because cells has various checkpoints to maintain the proper cell division. Their improper functioning can cause diseases like cancer. The cells has proper metaphase/ anaphase transitions check point that maintains the proper cell division.
The average star cycle: nebula, protostar, main sequence, red giant, white dwarf. The massive star cycle: nebula, protostar, main sequence, super red giant, supernova, black hole, neutron star.
The star cycle is the sequence of changes that a star undergoes throughout its existence.
<h3>The evolutive stages of an<u>
average star</u> are </h3>
- Nebula: Stars are born from the nebula that is the dust and gas particles condensation due to gravity effect in the interstellar clouds
- Protostar: It is a more advanced level of condensation.
- Main sequence. Equilibrium between gravity and nuclear fusion helps the star keep stable as long as the fuel lasts. The two main types are
• <em>Orange dwarf</em><em>: </em>between the red dwarf and the yellow dwarf
• <em>Yellow dwarf:</em> Like the sun
- Subgiant: occurs when orange and yellow dwarfs finish their main sequence and start to run out of fuel, expanding.
- Red giant. After the subgiant stage, the star enters a giant phase. The star can reach a size of up to 100 times its current size.
- White dwarf. When average-sized stars run out of fuel, the red giant begins to disintegrate, losing its outer layers and exposing its core, which will become a white dwarf.
<h3>The evolutive stages of a<u> </u><u>
giant star</u><u> </u>are </h3>
- Main sequence. There are two main types
• <em>Yellow supergiant</em>. Extremely short phase. Almost no stars are known to be in this stage. The star swells on its way to becoming a red supergiant.
• <em>Red supergiants</em> are the largest stars in volume, but not in mass.
- Supernova. When fuel is over in the red supergiants, the gravitational collapse produces a violent explosion originating the supernova.
- Neutron star. A celestial body that remains as a remnant after the explosion gives rise to a supernova.
You can learn more about the life cycle of stars at
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Answer: Sickle cell anemia is a molecular and genetic disease.
Sickle cell anemia is not infectious
Diseases caused by microorganisms are infectious.
Explanation: Sickle cell disease is a molecular disease,it involves molecular change in the structure of the molecular base present in the molecule DNA which caused the amino acids and the beta side of the hemoglobin to change accordingly.
It is genetic as it can be transferred from one generation to the next, children can inherit it from their parents.
A person can not be infected with Sickle cell anemia,it is not infectious unlike diseases caused by microorganisms that can infect others who come in contact with the disease either through blood or other routes.
You can find the number of neutrons by subtracting the number of protons from the atomic mass
It can help us no more about how to prevent global warming
