Jeffrey wants to lose weight by using caffeine to help with exercise. He asks himself, Which
caffeine drink will raise the heart rate the most?"
He tries to test this out by comparing the heart
rates of his neighbors, 3 brothers who are
triplets. One of the brothers drinks Pepsi,
another drinks a double shot of espresso (which
is coffee with twice the normal amount of
caffeine) and a third brother drinks only water for
comparison.
Jeffrey finds out that the triplet with the double
shot of espresso had the highest heart rate.
4. What is the independent variable for this experiment?

Many birth-control pills release a constant amount of synthetic estradiols and progesterone for 21 days, followed by 7 days when no hormones are ingested. which of the following statements most accurately describes the effects of birth-control pills? -birth-control pills maintain constant levels of estrogens and/or progesterone so there is no surge in lh and ovulation does not occur.-birth-control pills inhibit the development of the uterine lining so implantation of a fertilized oocyte cannot occur.-birth-control pills maintain constant levels of estrogens and/or progesterones and mask the release of the oocyte from the follicle.-the 7 days with no hormones does not allow a thick enough uterine lining to form so a fertilized oocyte cannot implant.