Answer:
Explanation:
Considering the atmosphere of the primitive earth to have contained water vapor, carbon dioxide, carbon monoxide, methane, and ammonia and/or nitrogen, then in the presence of an energy source, such as sunlight or lightning, a number of small molecules like hydrogen cyanide, HCN, are formed.
 
        
             
        
        
        
Answer: cartilage 
Explanation: because it is not hard or soft but it still is bone and that is what your ears and nose is made of 
 
        
                    
             
        
        
        
<em><u>Scientific Name of Touch-Me-Not Plant is Mimosa Pudica.
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The Touch-Me-Not Plant behaves like this because of stimuli. It responds to our sense of touch and curls up.
        
                    
             
        
        
        
Answer:
1. Signaling molecule
2. Signaling receptors 
Explanation:
Hormones, growth factors, neurotransmitters, etc. serve the function of signaling molecules for cells. These molecules are released by one cell and bind to the receptors present on/in the target cells to elicit the desired response. Thereby, the signaling molecules serve in cell-cell communication. 
For example, insulin hormone synthesized and released from beta cells of pancreas binds to its cell surface receptors present on the surfaces of liver cells and muscle cells to stimulate the uptake of the glucose from the blood.  
Likewise, neurotransmitters released from the presynaptic neuron bind to receptors present on the membrane of postsynaptic neuron and serve to carry the nerve impulse to the postsynaptic neuron.