When is S-phase complete?

Explanation:

The S phase only begins when the cell has passed the G 1 { G }_{ 1 } G1 checkpoint and has grown enough to contain double the DNA. S phase is halted by a protein called p16 until this happens.

The S Phase of Interphase

Explanation:

The S phase only begins when the cell has passed the G 1 {G}_{1} checkpoint and has grown enough to contain double the DNA. S phase is halted by a protein called p 16 until this happens.

d. the weight of the book

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.