Answer:
Main sequence stars fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. These stars can range from about a tenth of the mass of the sun to up to 200 times as massive.
Stars start their lives as clouds of dust and gas. Gravity draws these clouds together. A small protostar forms, powered by the collapsing material. Protostars often form in densely packed clouds of gas and can be challenging to detect.
"Nature doesn't form stars in isolation," Mark Morris, of the University of California at Los Angeles (UCLS), said in a statement. "It forms them in clusters, out of natal clouds that collapse under their own gravity."
Smaller bodies — with less than 0.08 the sun's mass — cannot reach the stage of nuclear fusion at their core. Instead, they become brown dwarfs, stars that never ignite. But if the body has sufficient mass, the collapsing gas and dust burns hotter, eventually reaching temperatures sufficient to fuse hydrogen into helium. The star turns on and becomes a main sequence star, powered by hydrogen fusion. Fusion produces an outward pressure that balances with the inward pressure caused by gravity, stabilizing the star.
How long a main sequence star lives depends on how massive it is. A higher-mass star may have more material, but it burns through it faster due to higher core temperatures caused by greater gravitational forces. While the sun will spend about 10 billion years on the main sequence, a star 10 times as massive will stick around for only 20 million years. A red dwarf, which is half as massive as the sun, can last 80 to 100 billion years, which is far longer than the universe's age of 13.8 billion years. (This long lifetime is one reason red dwarfs are considered to be good sources for planets hosting life, because they are stable for such a long time.)
Explanation:
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Answer:option C= mRNA
Explanation:
MACROMOLECULES are large molecules, such as protein, commonly created by the polymerization of smaller sub-units called monomers.
The NUCLEAR PORE is a protein-lined channel in the nuclear envelope. The NUCLEAR PORE regulates the transportation of molecules between the nucleus and the cytoplasm. In eukaryotic cells, the nucleus is separated from the cytoplasm and surrounded by a nuclear envelope.
mRNA is synthesized by DNA during a process known as the TRANSCRIPTION. After the synthesis, the new molecule moves from the nucleus to the cytoplasm. It passes through the nuclear membrane through a NUCLEAR PORE. Then, it will later join with a ribosome, which is just coming together from its two sub-units, one large and one small.
Answer: Genetics and Pressures
Explanation:
For natural selection to occur, a population must have a wide variety of individuals with different traits. For example, natural selection would not influence fish body color if all individuals in a population were exactly the same color. Variation of scale color can help a fish species have a higher chance of survival by confusing predators as to what species they are.
Reproductive strategies represent a set of behavioral, morphological, and physiological adaptations that facilitate access to potential mates, improve the chances of mating and fertilization, and enhance infant survival. Male peacocks have bright, big tail feathers, for example, to attract females. If an organism has a high appeal, this will make them more likely to be able to meet and continue the survival of the species.
Environmental pressures, such as plant death, could influence the survival of herbivorous organisms. Say a small land creature consisted off grass, and an epidemic killed all the grass in their region. They would either die off, or they would evolve to find different types of food. The former could reduce population, while the latter could increase it.
