Answer:
D
Explanation:
it just is i dont know y i just know it is D
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<u>cardic muscles:</u> are present only in the heart .single cell is not very strong by itself, millions of cardiac muscle cells working together are easily able to pump all of the blood in the body through the heart in less than a minute. Cardiac muscle cells have a branched shape so that each cell is in contact with three of four other cardiac muscle cells.
<u>characteristics of cardic muscles: </u> one nucleus ,striated, involuntary, branched and joined to one another by intercalated discs that contain gap junctions for depolarization between cells and hold the fibers together when the heart contracts.
Answer: c
Explanation: Plants and animals need nitrogen to make proteins but they cannot take it in from the air. Because nitrogen is unreactive as a gas, it has to be transformed into a new molecule. When bacteria in the soil takes nitrogen from the air, it becomes nitrates. Finally, it can move through the food chain in this form.
The thickness of the uterine lining , becomes very thick...because when the level of hormone progesterone reaches its highest levels. according to Dr.X on yahoo answers.
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