Biology help?

I just need help with these two... I just am at a loss for words at these. I know they're probably simple but I've been doing this stuff all night and I'm completely burnt out. Help would be deepy appreciated.

1. Describe how red blood cells absorb and transport oxygen.

2. Do arteries carry oxygenated blood or deoxygenated blood? Explain.

Thanks!
(1) Red Blood Cells contain a protein-iron molecule called Haemoglobin which binds oxygen.

When the RBC enters the lung capillary, it is exposed to oxygen and the O2 binds to the haemoglobin (Hb) to form oxygenated haemoglobin (Hb-O2).

This is then circulated to other organs where the oxygen can be delivered to the tissues.

(2) Arteries can carry either oxygenated blood or deoxygenated blood (or even in some disease processes they can carry a mixture of both).

The aorta commonly carries blood that has returned from the lungs (oxygenated) and entered the Left Atrium, passed through the Mitral (or bicuspid) valve and been ejected from the Left Ventricle. The aorta supplies MOST of the arteries of the body and hence most arteries carry OXYGENATED blood.

However, the blood that has returned from the body (the deoxygenated blood) enters the Right Atrium, passes through the Tricuspid valve and is ejected from the Right Ventricle into the Pulmonary Arteries. These arteries carry the deoxygenated blood to the LUNGS where it becomes oxygenated again.

It is more accurate to state that ARTERIES carry blood AWAY from the heart.

NB. in certain conditions such as Atrial Septal Defect or Tetralogy of Fallot, there can be mixing of oxygenated and deoxygenated blood within the heart, and the aorta and the rest of the arterial system can carry mixed blood in these patients.

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