The inner lining of the stomach is protected from hydrochloric acid by which of the following? Choose the correct one:

Choose the correct path of urine in our body:

Why does absorption of digested food occur mainly in the small intestine?

Which of the following statement$(s)$ is (are) correct?
$(i)$ Pyruvate can be converted into ethanol and carbon dioxide by yeast.
$(ii)$ Fermentation takes place in aerobic bacteria.
$(iii)$ Fermentation takes place in mitochondria.
$(iv)$ Fermentation is a form of anaerobic respiration.

Lack of oxygen in muscles often leads to cramps among cricketers. This results due to:

$(a)$ What is the nature of food coming from the stomach?
$(b)$ Mention any two structural modifications in the small intestine which help in the absorption of food.