Explanation:
Results in a decline in CD4+T cell numbers below the critical level, and loss of cell-mediated immunity. Therefore the body becomes progressively more susceptible to opportunistic infections and cancer.
 
        
             
        
        
        
Phloem is the food conducting tissue that has a two-way flow. 
Explanation:
Plants prepare food on their own and plants also have conductive cells that carry out transportation process. Plants are divided into two types based on their conductive system i.) vascular plants  ii.) non vascular plants.
Vascular plants are those plants which have special conductive cells called phloem and xylem.
Xylem transports water from roots of the plants to other parts of plants and also provides mechanical support to plant. It is uni-directional.
Phloem is the food conducting tissue that transports food to plant and also have bi-directional movement.
 
        
             
        
        
        
Answer:
Polar molecules must contain polar bonds due to a difference in electronegativity between the bonded atoms.
Explanation:
 
        
             
        
        
        
It helps in digestion of food