The answer is 1.01 x 10^(-11) N. I arrived to this answer through calculating the GPEs of both balls. Bjorn's ball has a GPE of 1.402 x 10^(-11) N. Billie Jean's ball has a GPE of <span>2.503 x 10^(-11) N. I subtracted the two and I found that Billie Jean's tennis ball has a GPE of 1.01 x 10^(-11) more than Bjorn's tennis ball.</span>
Wood frogs have this adaptation where they accumulate urea in their bodies and convert their liver glycogen to glucose to act as cryoprotectants. This prevents the formation of ice crystals in their bodies that could cause damage cells during freezing in winter.