Which is the first enzyme to mix with food in the digestive tract?

Which is the correct sequence of parts in the human alimentary canal?

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

Single circulation,i.e.,blood flows through the heart only once during one cycle of passage through the body,is exhibited by:

Choose the function of the pancreatic juice from the following:

Explain the role of the mouth in the digestion of food.