15. Slaivary glands are stimulated to release digestive enzymes by
and
of food.

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In reaction to the smell, sight, or thought of food, the first hormonal response is that of salivation ( starts making saliva )  The salivary glands secrete more saliva in response to the stimulus presented by food in preparation for digestion. Simultaneously, the stomach begins to produce hydrocholoric acid to digest the food  

The salivary glands are glands inside a person's mouth and throat that produce the watery and mucous-containing fluid known as saliva. Saliva is constantly released into our mouth to keep it lubricated and to help us chew and swallow food. There are three pairs of salivary glands: sublingual, parotid and submaxillary

and for the end the main digestive enzymes in your body are : -

1- Amylase, produced in the mouth. It helps break down large starch molecules into smaller sugar molecules.

2- Pepsin, produced in the stomach. Pepsin helps break down proteins into amino acids.

3- Trypsin, produced in the pancreas. Trypsin also breaks down proteins

4- Pancreatic lipase, produced in the pancreas. It is used to break apart fats.

5- Deoxyribonuclease and ribonuclease, produced in the pancreas. They are enzymes that break bonds in nucleic acids like DNA and RNA

1: most common garden plants prefer loam — soils with a balance of different-sized mineral particles (approximately 40% sand, 40% silt, and 20% clay) with ample organic matter and pore space. however, some plants grow better in sandy soils, while others are well-adapted to clay soils.

2: available water capacity is the maximum amount of plant available water a soil can provide. it is an indicator of a soil's ability to retain water and make it sufficiently available for plant use. available water capacity is the water held in soil between its field capacity and permanent wilting point.

3: it is the same for all living things (plants and animals). it also includes very tiny organisms that our eyes cannot see. they are known as microorganisms, and include viruses, bacteria and fungi.