Which of the following structures is lined by guard cells?

Which of the following statements best summarizes the relationship between respiratory rate and body size in related animals?

Breathing differs from respiration by

Percentage of $O_2$ present in inhaled air in man is about (in $\%$)

Select the correct statements from the following regarding gaseous exchange in plants.
$A$. $A$ terrestrial plant has many air spaces between the cells of leaf and root.
$B$. Woody trees have stomata on bark.
$C$. In aerated soil,oxygen dissolved in water enters root tissue by diffusion.
$D$. Vascular bundles provide thin and large surface area for exchange of gases.
$E$. Carbon dioxide and water vapour diffuse into lenticels.

Which of the following statements is correct?