What is the main toxic waste that the kidneys filter from the blood?

Which of the following statement$(s)$ is (are) true about respiration?
$(i)$ During inhalation,ribs move inward and diaphragm is raised
$(ii)$ In the alveoli,exchange of gases takes place i.e.,oxygen from alveolar air diffuses into blood and carbon dioxide from blood into alveolar air
$(iii)$ Haemoglobin has greater affinity for carbon dioxide than oxygen
$(iv)$ Alveoli increase surface area for exchange of gases

Draw the diagram of the alimentary canal of a human and label the following parts:
Mouth,Oesophagus,Stomach,Intestine.

Choose the correct statement that describes arteries.

$A$ few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains:

Name the cell organelle in which the breakdown of pyruvate to give carbon dioxide,water,and energy takes place.