Which genetic disorder causes red blood cells to change shape
during periods of low oxygen?

Which of the following is an effect of the uneven heating of the earth by the sun? a sea breeze a land breeze a convection current all of the above

20. in humans, freckles are dominant to no freckles. trey has no freckles and his wife anna grace has freckles, but her dad doesn't. they want to know what percentage of their kids would look like trey. show a punnett square to support your answer.

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins