The hydrogen used to produce ATP in the light reactions of photosynthesis comes from ___. a. Splitting water
b. Carbon fixation
c. Movement of hydrogen ions through the membrane
d. The burning of sugar molecules

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

answer: b

coz red blood cells marrow and circulates the body for 120 days.

answer; synapse;