Answer:
Hormones act as first messenger but not as second messengers.
Explanation:
Second messenger act as signaling molecule which are secreted in response to various biological signals generated by first messenger such as hormones,neurotransmitters etc.Second messengers include various bioactive molecules such as cyclic AMP(cAMP),cyclic GMP(cGMP),inositol triphosphate(IP3),diacylglycerol(DAG),calcium ions(Ca2+) etc.
          Hormones are extracellular signaling molecules whereas second messengers are intracellular signaling molecules.
 
        
             
        
        
        
<span><span>1 Corundum
</span><span>2 Topaz
</span><span>3 Quartz
4 </span><span>Orthoclase
</span><span>5 Apatite
6 </span><span>Fluorite
7 </span><span>Calcite
8 </span><span>Gypsum
</span><span>9 Talc
Are all answers to what diamond on a scale of minerals can scratch.
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D oxygen there was no free oxygen on the earth
        
             
        
        
        
Answer:
Humans cannot occupy the lowest levels.
Explanation: