Saliva,unprotected intercourse,contact with infected blood (blood transfusion) 
and women with an unborn child.
        
             
        
        
        
The classifications of the carbon as primary secondary tertiary and quaternary depends on the number of the carbon atoms attached to a carbon. In case, the carbon is attached to a single carbon, then it is referred as primary carbon. If the carbon is attached to two carbons, then it is referred as the secondary carbon, if the carbon is attached to three carbons then it is referred as tertiary, and if the  carbon forms all the bond with another carbon atom then it is referred as quatenary carbon.
The given below is the picture showing the primary, secondary, tertiary, and quarternary carbons in 4-isopropyl-2,4,5-trimethylheptane:
 
        
             
        
        
        
Answer:
The correct answer would be - medium with lactose present and glucose absent.
Explanation:
There are genes present in lac operon that takes part in the lactose metabolism. These genes expressed only if a medium has lactose in absence of glucose.
In the absence of glucose and lactose is present, due to inducer the lac repressor is removed from the operator. This leads to the binding of CAMP to DNA as the CAMP levels are high. It helps in high transcription levels b binding RNA polymerase to promotor.
 
        
             
        
        
        
Answer:
Molarity is the most useful concentration for chemical reaction in solution ... As an example, suppose we dissolve 23 g of ammonium chloride (NH4Cl) in enough water ... Now, suppose we have a beaker with 175 mL of a 0.55 M HCl solution.Explanation:
 
        
             
        
        
        
Stimuli is detected by receptor cells . These stimuli are converted to electrical nerve impulses carried by sensory neurone to relay neurone where it is processed by Central Nervous System . The response is carried by the motor neurone to the effector s which are muscles or glands which reacts to the situation