To investigate whether roots exert a pushing force strong enough to cause water to move up the stems plants, my question is state and explain 4 precautions to be considered during the setup of this experiment

The stem of the plant should be cut at least three to four inches above the surface level.
The glass capillary should be tightly fixed with the stem.
The initial water level and the final water level should be carefully noted.
The droplets on the leaves should be observed and conclude that these drops are not from transpiration. 

the glands which are associated with each description is given below:

pancreas - is an endocrine and exocrine gland that secretes juices with enzymes for digestion. salivary glands- with protection and digestion in the mouth. liver- secretes bile for digestion.   lachrymal glands - secrete tears to moisten eyes and protect them from particles and infection.   sweat gland -regulates water, salt, and temperature. oil glands - to form a protective barrier on the skin.   goblet cells - secrete mucus for protection.