Bacteria live in a variety of locations one of which is the human mouth. which explanation supports the wide variety of bacteria in the mouth? a. accessibility to air cause bacteria to change form. b. salivary glands cause mutations in populations of bacteria. c. accessibility to nutrients makes the mouth a favorable habitat. d. calcium in the teeth provides appropriate ph levels in the mouth.

i'd say that the moon rock is about 2.2 billion years old.

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.