Which of the following choices describes the correct order of events that occur during the cardiac cycle: i. The mitral and tricuspid valves open and the atria force blood into the ventricles. ii. The ventricles contract and push the blood out. iii. The heart relaxes in diastole and the atria fill with blood. iv. The ventricles fill with blood

Aresearcher has developed two stains for use with seed plants. one stains sporophyte tissue blue; the other stains gametophyte tissue red. if the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur? a) the pollen grains will be pure red.b) the pollen grains will be pure blue.c) the pollen grains will have red interiors and blue exteriors.d) the pollen grains will have blue interiors and red exteriors.

Which of the following produces carbon dioxide? a. plants b. animals c. decomposers d. all of the above

About __ of the mass of the cell is water