In which part of the digestive system is water absorbed?

When air is blown from the mouth into a test-tube containing lime water,the lime water turns milky due to the presence of:

Choose the event that does not occur in photosynthesis.

Just as $CO_{2}$ is removed from the blood in the lungs,nitrogenous wastes such as urea or uric acid are removed from blood in the liver.

What causes the movement of food inside the alimentary canal?

What prevents backflow of blood inside the heart during contraction?