discribe the passive transport movement of a substance down it's concentration gradient through a protein channel embedded in the cell membrane

The passive transport of a substance by its concentration gradient through a protein channel is called facilitated diffusion.

Explanation:

Facilitated diffusion is a type of passive transport through the membrane, which involves the use of integral proteins called protein channels or transport proteins, and moves substances unable to cross the membrane by simple diffusion.

An example of facilitated diffusion through protein channels is the ion channel. Ions, being electrically charged particles, cannot pass through the plasma membrane. A protein channel -which crosses the whole thickness of the membrane- constitutes a space where ions can move depending on their concentration gradient.

In facilitated diffusion, both protein channels and transport proteins do not require energy, so it is a transmembrane passive transport process.

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.