Catalysis is the process of influencing the chemical bonds in a way that lowers the needed to speed up a chemical reaction. a heat energyb free energyc activation energyd enzyme

the wires in the toaster turning red and the toast crisping and turning brown

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.