<u>Smoking</u> causes respiratory disorders such as bronchitis, pneumonia and lung cancer.
<u>Explanation:</u>
Respiratory disorders such as bronchitis, pneumonia and lung cancers are caused by smoking tobacco, air pollution and by infection. Smoking is the predominant cause of this respiratory order it also raises the level of air pollution which becomes hazardous to all the living organisms.
Infection in the lungs which is identified as pus in air sacs and found as inflamed lungs is usually life threatening. Severe shortness of breathe called the bronchitis is due to airborne chemicals.
During the S phase in the cell cycle, the chromosomes are replicated so that there are two copies. These copies are necessary so that each daughter cell created during the M phase will have an identical copy of the DNA.
Therefore, the answer is A: The DNA must be replicated.
The chromosomes joining, cell membrane expanding, and cytoplasm separating all happen during the M phase (mitosis).
Examples of physical changes in properties are melting, transition to a gas, crystallization, etc
Answer:
The main sequence stretching from the upper left (hot, luminous stars) to the bottom right (cool, faint stars) dominates the HR diagram. It is here that stars spend about 90% of their lives burning hydrogen into helium in their cores. Main sequence stars have a Morgan-Keenan luminosity class labelled V.
Explanation:
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