Which is the lowest level of organization of the system

Explanation:

Molecules are made of atoms, the smallest unit of chemical elements. They can be found in all matter, living and non-living

An organ system is a group of organs that work together to perform specific bodily functions. The respiratory system, for example, uses the lungs, airways and respiratory muscles to inhale oxygen and release carbon dioxide in animals.

Explanation is in the file

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the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.

not: both offer magnification to the atomic level.