Answer:
Water and nutrient uptake.
Explanation:
The root system of a plant functions as conducting tissue for water and mineral nutrients that are essential for metabolic activities of the plant. 
<em>Extensive surface area of roots is an adaptation associated with efficient water and mineral nutrient uptake because this will increase the surface area of roots in contact with the soil.</em>
 
        
             
        
        
        
Nucleic acids / aka nucleotides
        
             
        
        
        
Answer: A specific chemical binding to nociceptors
Explanation:
 
        
             
        
        
        
Answer:
Option A
Explanation:
Thyroid is primarily caused by lack of iodine but there are other reasons as well that lead to increased size of the thyroid gland. Some of these reason is 
a) over- or underproduction of thyroid hormones
b) Nodules in the glans
Some times, due to overstimulation immune system itself attack the thyroid gland thereby producing excess thyroxine and hence causing  the thyroid to swell
Thus, Option A is correct