What substances are involved in controlling the production of sperm and eggs in humans

The substances that are involved in the control of sperm and egg productions in humans are the Hormones. They play important role in regulating both female and male reproductive cycles. The primary hormones involved in male reproductive system are follicle stimulating hormone, leutenizing hormone and testosterone while in females reproductive system we have Gonadotropin releasing hormone, LH, FSH, estrogen, and progesterone. The entire reproductive systems are dependent on hormones in the stimulation and regulation. 

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun

There would be no evaporation so no water cycle