why diffusion of air occurs only in alveolar region and not in other parts of respiratory system ?

Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why?

Why is that in certain plants deficiency symptoms appear first in younger parts of the plant while in others they do so in mature organs?

Each phase of a material can exits only in certain regions of pressure and temperature . P-T phase diagrams, in which pressure is plotted versus temperature, show the regions corresponding to various phases and phase transformations . P-V diagrams, on the other hand , can be used to study pressure volume relationship at a constant temperature. If the liquid and gaseous phases of a pure substances are heated together in a closed container, both the temperature and the vapor pressure will increase until a point is reached at which the two phases can no longer be distinguished from one another. The temperature and pressure at which this occurs are called the critical temperature and pressure. Exceeding either of these parameters, by itself ,will cause the "gas"//"liguid" phase transition to disappear. if the other variable is then changed as well, while the first variable is maintained above its critical point , a gradual transition will occur between the gaseous and liquid phases, with no clear boundary.(The liquid and solid phases, on the other hand , maintain a distinct boundary at all pressure above the triple point). Shown in figure is a combined P-T phase diagram for material A and B . If heat is added to solids A and B , each in a container that is open to the atmosphere :-

Each phase of a material can exits only in certain regions of pressure and temperature . P-T phase diagrams, in which pressure is plotted versus temperature, show the regions corresponding to various phases and phase transformations . P-V diagrams, on the other hand , can be used to study pressure volume relationship at a constant temperature. If the liquid and gaseous phases of a pure substances are heated together in a closed container, both the temperature and the vapor pressure will increase until a point is reached at which the two phases can no longer be distinguished from one another. The temperature and pressure at which this occurs are called the critical temperature and pressure. Exceeding either of these parameters, by itself ,will cause the "gas"//"liguid" phase transition to disappear. if the other variable is then changed as well, while the first variable is maintained above its critical point , a gradual transition will occur between the gaseous and liquid phases, with no clear boundary.(The liquid and solid phases, on the other hand , maintain a distinct boundary at all pressure above the triple point). Shown in figure is a combined P-T phase diagram for material A and B . Which is true about the substance in figure?

Two guns situated at the top of a hill of height 10 m fire one shot each with the same speed 5sqrt(3) m//s at some interval of time. One gun fires horizontal and the other fores upwards at an angle of 60^(@) with the horizontal. Two shots collide in air at a poit P . Find (i) time-interval between the firing and (ii) coordinates of the point P . Take the origin of coordinates system at the foot of the hill right below the muzzle and trajectorise in the x-y plane.

Maximum value of the objective function Z = ax + by in a LPP always occurs at only one corner point of the feasible region.