<span>The protocell's fatty acid membrane allows chemical compounds, including the building blocks of DNA, to enter into the cell without the assistance of the protein channels and pumps required by today's highly developed cell membranes</span>
Answer:
Explanation:
1- the purpose of blood flow-circulatory system- is to convey Oxygenated blood, oxygen bonded with haemoglobin in the RBC with Nutrients - and distributed these through the arteries and capillaries away from the heart, to reach the cells and tissues, and transported the wastes of theses cells and tissues , with C02 through the veins back to the heart and the kidney.
2. During diastole,deoxygented blood from the inferior and superior vena cavae entering the R.atrium, passes through the tricuspid valve into the Right Ventricle. Simultaneously, oxygenated blood returning through the pulmonary veins enters the left Atrium,emptied through the bicuspid valve into the Left.Ventricle.
During systole, the two ventricles contracts. The Right ventricle contracts, the pressure of the blood forces the tricuspid valve to close,and therefore de -oxygenated blood pushes the pulmonary valves to open and blood passes through the pulmonary artery to reach the lungs where exchanges of oxygen with carbon dioxide occurs.The blood is now oxygenated and returns to the left atrium via pulmonary veins.
Simultaneously, the left ventricle contracts,the oxygenated blood it contains forced the bicuspid valve to close so that blood is forced through the aortic valve to empty into the aorta into the systemic circulation,branches of the carotid artery supplies the heart from the aorta.
The Whole cycle continues.
Answer:
Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust. (Sometimes, oceanic crust may grow so old and that dense that it collapses and spontaneously forms a subduction zone, scientists think.)
Explanation:
The answer for this question is B
