Background: Animals and some bacteria and fungi carry out lactic acid fermentation. Lactic acid is a waste product of this process. Our muscles perform lactic acid fermentation during strenuous exercise, since oxygen cannot be delivered to the muscles quickly enough. The buildup of lactic acid is believed to make your muscles sore after exercise. Bacteria that produce lactic acid are used to make cheese and yogurt. The lactic acid causes the proteins in milk to thicken. Lactic acid also causes tooth decay, because bacteria use the sugars in your mouth for energy.

Situation: Mark and Jerry are brothers. Mark just got done working out and returned home to find his brother laying down on the couch eating a bag of potato chips. Mark comments that Jerry should really come and work out with him some time. Jerry brushes him aside.

Question: Which person's muscles are not getting enough oxygen?
Answer: Mark

Situation: Mark and Jerry are brothers. Mark just got done working out and returned home to find his brother laying down on the couch eating a bag of potato chips. Mark comments that Jerry should really come and work out with him some time. Jerry brushes him aside.

Question: Which person's body has less lactic acid?
Answer: Jerry

Situation: Mark and Jerry are brothers. Mark just got done working out and returned home to find his brother laying down on the couch eating a bag of potato chips. Mark comments that Jerry should really come and work out with him some time. Jerry brushes him aside.

Question: Which person's muscles are getting enough oxygen?
Answer: Jerry

Situation: Mark and Jerry are brothers. Mark just got done working out and returned home to find his brother laying down on the couch eating a bag of potato chips. Mark comments that Jerry should really come and work out with him some time. Jerry brushes him aside.

Question: Which person's body has more lactic acid?
Answer: Mark

Situation: Tony and Greg are brothers. They are currently in the kitchen eating a snack together. Greg is eating a stalk of celery while Tony is eating out of a bowl of candy. Tony remarks that he doesn't know how Greg enjoys such a bland snack. Greg just gives Tony an angry glare before getting up to go into the living room. On the living room table, Greg finds a glass of milk and a bowl of milk. The glass of milk has started to get thick, but the bowl of milk appears to be still fresh. Greg rolls his eyes at the mess and walks away.

Question: Which person will experience more tooth decay?
Answer: Tony

Situation: Tony and Greg are brothers. They are currently in the kitchen eating a snack together. Greg is eating a stalk of celery while Tony is eating out of a bowl of candy. Tony remarks that he doesn't know how Greg enjoys such a bland snack. Greg just gives Tony an angry glare before getting up to go into the living room. On the living room table, Greg finds a glass of milk and a bowl of milk. The glass of milk has started to get thick, but the bowl of milk appears to be still fresh. Greg rolls his eyes at the mess and walks away.

Question: Which person will experience less tooth decay?
Answer: Greg

Situation: Tony and Greg are brothers. They are currently in the kitchen eating a snack together. Greg is eating a stalk of celery while Tony is eating out of a bowl of candy. Tony remarks that he doesn't know how Greg enjoys such a bland snack. Greg just gives Tony an angry glare before getting up to go into the living room. On the living room table, Greg finds a glass of milk and a bowl of milk. The glass of milk has started to get thick, but the bowl of milk appears to be still fresh. Greg rolls his eyes at the mess and walks away.

Question: Which container of milk has more lactic acid?
Answer: glass

Situation: Tony and Greg are brothers. They are currently in the kitchen eating a snack together. Greg is eating a stalk of celery while Tony is eating out of a bowl of candy. Tony remarks that he doesn't know how Greg enjoys such a bland snack. Greg just gives Tony an angry glare before getting up to go into the living room. On the living room table, Greg finds a glass of milk and a bowl of milk. The glass of milk has started to get thick, but the bowl of milk appears to be still fresh. Greg rolls his eyes at the mess and walks away.

Question: Which container of milk has less lactic acid?
Answer: bowl