9. The oral contraceptive pill, informally called “the pill,” contains an estrogen and progesterone, or a synthetic mimic of this hormone. The combination of these two hormones, taken in the pill and circulating in the blood, works because ________.        

20. All veins carry deoxygenated blood.

23. Which male hormone provides negative feedback for the secretion of FSH?        

44. The correct sequence of preembryonic structures is ________.        

13. Respiratory control centers are located in the ________.        

3. Female orgasm is required for conception.

43. Systole is contraction of the muscle. Diastole is relaxation of the muscle. 

47. The heart murmur is due to complete closure of the pulmonary valve and regurgitation of pulmonary trunk blood during diastole.

46. Muscle tissue is formed by the ________.        

49. A urine test reveals a positive result for human chorionic gonadotropin (hCG). This indicates ________ was successful.