Biology Lesson

In a biology class, the professor was discussing the high 
Glucose levels found in semen. A female freshman raised her 
hand and asked, "If understand,you're saying there is a lot 
of glucose, as in sugar, in semen?" 
"That's correct," responded the professor, going on to add 
Statistical info. Raising her hand again, the girl asked, 
"Then why doesn't it taste sweet?" 

After a stunned silence, the whole class burst out 
laughing, the poor girl'sface turned bright red, and as 
she realised exactly what she had inadvertently said 
(or rather implied), she picked up her books without a word 
and walked out of class, never to return. 

However, as she was going out the door, the Prof's reply 
was classic. 
Totally straight-faced he answered her question. "It doesn't 
taste sweet because the taste buds for sweetness are on the 
tip of your tongue and not the back of your throat.