Diffusion, movement of particles across a membrane is driven by differences in
a. concentration.
b. shape.
c. force.
d. size.

A concentration.

In cells, there are two types of transportation of needed organic compounds. The active and passive transport.
The active transport requires energy or ATP while passive doesn't. Further, diffusion, a passive transport transfers compounds from higher to lower concentrations. 

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.

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