Answer:
1.) Why does menstruation begin?
A.) Period happens because of changes in hormones in the body.
2.) How long does the menstrual cycle usually last?
A.) the menstrual cycle lasts 21 to 35 days while bleeding between 2 to 7 days
<u>-TheUnknownScientist</u>
Answer:
When blood clotting is activated, fibrinogen circulating in the blood is converted to fibrin, which in turn helps to form a stable blood clot at the site of vascular disruption.
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Answer:B. Sunlight provides energy to producers
Explanation: photoautotrophs (plants) produce energy from sunlight by photosynthesis. This is the only energy production based on an external source of energy. Plants, whether alive or dead, are consumed by heterotrophs - bacteria, fungi and animals. The nutrients and energy from dead heterotrophs (and some live ones) are recycled by both autotrophs and heterotrophs.