Explanation:
Cuando los niveles de testosterona están bajos, la hormona liberadora de gonadotrofina (GnRH) es liberada por el hipotálamo que a su vez estimula la glándula pituitaria para liberar LH. Esta última hormona estimula los testículos para sintetizar la testosterona.
 
        
                    
             
        
        
        
The post-eradication era is a period of history for which there has been no precedent whatsoever in terms of a zero base of immunity. Cessation of immunization will eventually create a population susceptible to widespread infection in the event of accidental or intentional reintroduction or re-emergence of the eradicated virus. Thus, even after immunization ceases, vaccine production must continue.
However, many currently available vaccines may not be appropriate for continued post-eradication vaccine production or reinstatement. Vaccines must be continually improved and ongoing vaccination research maintained. Other potentially useful antiviral strategies—antivirals, prophylaxis, and probiotics—must also be considered as means to strengthen the immune system and serve as adjuvant or prophylactic therapies.
In the case of polio, for example, it remains to be determined which vaccine (oral polio vaccine [OPV] or inactivated polio vaccine [IPV]), or variant thereof, should be produced in the post-eradication, post-vaccination era. A detailed plan for vaccine production will require more information on OPV-derived viral persistence and transmission, as well as continuing dialogue between public health and research communities in order to ensure that appropriate vaccination research continues.
 
        
                    
             
        
        
        
The astronomical unit, otherwise known as AU is used to measure long distances in the universe.
In photosynthesis oxygen is released to the atmosphere which means the third option is correct.
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This refers to a trait that should be able to be treated with antibiotics but instead the trait has built up a resistance to this trait, sometimes this will even make the trait stronger. This can become fatal if the trait is resistant to all antibiotics available
        
                    
             
        
        
        
Answer:
They are necessary so they can be added to the carboxyl and amino function groups
Explanation:
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