Answer: The answer is BOUNDARY 
Explanation:
 
        
             
        
        
        
Homeostasis is the maintenance of a stable internal environment. Homeostasis is a term coined to describe the physical and chemical parameters that an organism must maintain to allow proper functioning of its component cells, tissues, organs, and organ systems.
 
        
             
        
        
        
Answer:
<h3>1. producers releasing it as a product of photosynthesis </h3>
Explanation:
I hope it helps ❤❤
 
        
             
        
        
        
<em>sieve tube elements are the cells of phloem which allow transportation of photosynthates through phloem...
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how sieve tube elements form sieve tubes:
</u>sieve tube elements are connected end to end and form a long chain which is called sieve tube,,,,
sieve tube elements are connected with the help of a side chain with the help of peptide bond...also one element has tapering end which easily overlaps with other end of next element to form sieve tube,,,,</em>