James was exposed to a pathogen when he was 10 years old and felt ill. what would most likely happen if he were exposed to the same pathogen when he is 12 years old? a his body would destroy the pathogen before he felt symptoms. b his reaction to the pathogen would be worse than the first. c his antibodies would decrease, since he had been exposed already. d new types of antibodies would be made in response to the second exposure.

Ans. (A). His body would destroy the pathogen before he felt symptoms.

The immune system works to protect the body against pathogenic microbes or and tumor cells. When an antigen enters the body for the first time, B cells of immune system make effector cells and memory cells.

The effector cells provide response against target antigens (first immune response), while memory cells go in blood circulation and respond against that antigen on its re-exposure. The second immune response is faster and more effective than first immune response.

Hence, James has memory cells for that pathogen, during its first exposure and these memory cells were show faster response against the pathogen, when it enters for the second time.  

Thus, the correct answer is option (A).

A.)His body would destroy the pathogen before he felt symptoms.

Explanation: a because his body will have already fought it and will basically know what to do to fight it again. its kinda like some illnesses where you get it ounce and cant get it again because they are now immune except he wont be amine to it his body would just be better prepared.

advantage of using stem cells in medical research:

1.       it provides medical benefits in the fields of therapeutic cloning and regenerative medicine.

2. it provides great potential for discovering treatments and cures to a variety of diseases including parkinson disease, spinal cord injuries, diabetes, alzheimer’s disease and many more.

3. limbs and organ could be grown in lab from stem cells and then used in transplant or treat illness.