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

$(a)$ State the reason for the following:
$(i)$ Herbivores need a longer small intestine,while carnivores have a shorter small intestine.
$(ii)$ The lungs in human beings are designed to maximize the area for the exchange of gases.
$(b)$ The rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.

During respiration,the exchange of gases takes place in:

The correct sequence of anaerobic reactions in yeast is:

Which is the correct sequence of air passage during inhalation?

Which of the following statements 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.