Why do gymnosperms and grasses produce more pollen than most angiosperms

production of pollen grains depends MOSTLY on the agents of pollination ( Insects, wind,  animals , and birds ).

There is a great deal of wastage of pollen when it is carried by wind ( Anemophylous plant = wind pollinated plants

Explanation:

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.