The answer will be (d)- the conclusions will be inaccurate.
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:
False
Explanation:
The blood brain barrier (BBB) is a selective border that prevents the entry of foreign substances into the brain. It is made up of different components including endothelial cells, astrocytes, and pericytes etc.
Of all these mentioned three, the endothelial cells are directly responsible for the selectivity of the BBB. The endothelial cells are bound together by the tight junctions situated between them, impeding the passage of foreign materials e.g. solutes, pathogens etc.
Astrocytes help to maintain the BBB by surrounding the endothelial cells, providing biochemical strength.
The pericytes are located in the basement membrane, where they communicate with endothelial cells. They help to sustain the BBB by stabilizing and monitoring the maturation of endothelial cells via communicating directly between cell membrane as well as paracrine signalling.
A. carbs,proteins, and fats
