Hey dear!
option A. covalent is correct
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Answer:
No
Explanation:
If the earth was tilted, there would be small changes in temperature, but there will be no seasons. The Earth's axis is now inclined at around 24 degrees. This is the main reason for the changing of the seasons. The Northern Hemisphere is in the warm season when the Earth is slanted toward the sun, and the Northern Hemisphere is in the cold season when the Earth is slanted away from the sun. The cycle repeats itself every year because the Earth rotates around the sun at a known and generally constant rate. The sun is higher in the sky during the warm season, making it warmer, and lower in the sky during the cool season, making it colder.
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-jp524
False. Streams lose velocity when the slope of the stream bed decreases.
The atoms in a water molecule are held together through a covalent bond.
Answer:
This question includes some errors, the question should be written as:
The medulla oblongata controls the contraction and relaxation of the ______ causing the lungs to inflate and deflate during breathing.
Although there are no options, the answer is generally RESPIRATORY MUSCLES i.e. diaphragm and intercostal muscles
Explanation:
Breathing is an involuntary action required to take place in order to get oxygen into the system and carbon dioxide out of the system. However, the process of breathing is neurally controlled by brain portion called RESPIRATORY CONTROL CENTERS.
The Medulla oblongata located in the hindbrain is one of the two respiratory control centers (the other being the PONS). The medulla sends nerve signals to the muscles responsible for bringing about the ventilation process i.e. the DIAPHRAGM and INTERCOSTAL MUSCLES.
This nerve impulse brings about the contraction of the diaphragm, which is the major respiratory muscle, and intercostal muscle causing the lungs to inflate and allow the entry of oxygen-containing air. On the other hand, it also brings about the relaxation of these muscles causing the lungs to deflate allowing the expelling of air.