Why do we have a respiratory system?
What are the main structures of the respiratory system?
How does the respiratory system work?
How does the respiratory system work together with other systems?

 We have a respiratory system which helps us to breathe in and out. We use this system all day and everyday. The respiratory system helps us to breathe. The respiratory system works with the human inhaling oxygen from the nose or mouth. The oxygen then goes to the trachea which carries it down to the lungs. The lungs then can transport that oxygen to cells. For exhaling, the lungs exert Carbon dioxide that travels to the bronchi then up your trachea and Carbon dioxide comes out either from your nose or mouth depending which you use to breathe. The trachea also widen and lengthens as inhale and it returns to its normal size when your breathing is done. The respiratory system is related to the circulatory system. It can transport the oxygen to the cells which the cells can travel through arteries to transport it throughout the body. The main structures of the respiratory system are the lungs, trachea, nose, mouth, larynx, and more.

Explanation:

Hope this helps!

The lungs and respiratory system allow oxygen in the air to be taken into the body, while also enabling the body to get rid of carbon dioxide in the air breathed out. Respiration is the term for the exchange of oxygen from the environment for carbon dioxide from the body's cells.There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The airway, which includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles, carries air between the lungs and the body's exterior.The respiratory system works directly with the circulatory system to provide oxygen to the body. Oxygen taken in from the respiratory system moves into blood vessels that then circulate oxygen-rich blood to tissues and cells.The circulatory and respiratory systems work together to circulate blood and oxygen throughout the body. Air moves in and out of the lungs through the trachea, bronchi, and bronchioles. Blood moves in and out of the lungs through the pulmonary arteries and veins that connect to the heart.

Explanation:

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.

answer; i believe the correct answer is (a)0