1. Explain why testosterone can improve performance in sport. 2. Describe the role of oestrogen in the menstrual cycle.

1How does testosterone enhance performance? Testosterone acts on muscle cells by binding to a specific receptor protein, the androgen receptor. Upon testosterone binding, the androgen receptor signals to the muscle cell to activate the pathways that trigger an increase in muscle mass, called muscle hypertrophy.

2The oestrogen causes growth and repair of the lining of the uterus wall. Oestrogen inhibits FSH. When oestrogen rises to a high enough level it causes a surge in LH from the pituitary which causes ovulation where an egg is released from the follicle (Day 14 of the cycle).

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

this transfer is call conjunction