Answer:
genetic drift
Explanation:
Genetic drift is an evolutionary force that requires the presence of a small population. It is a random process that fixes one or other alleles randomly in the gene pool of a population. Genetic drift does not take account of survival fitness imparted by alleles to the individuals. Since random and chance events such as the death of all the individuals having a certain allele in a population affect the small population more intensely, genetic drift works on small populations only.
 
        
                    
             
        
        
        
Answer:
increasing[1], higher[2], space[3], food[4], climate change[5].
Explanation:
Because global temperatures are <u>increasing[1]</u>, some species are seeking out <u>higher[2]</u> elevations in the Himalayas to colonize.  Scientists were worried that these organisms would not have enough <u>space[3]</u> to live, but they have found that there is adequate <u>food[4]</u> at higher elevations. This movement may help these organisms survive the effects of <u>climate change[5].</u>
(Although am positive about 1, 2 and 5, you will need to double check 3 and 4.  What I can tell you is that I don't think lifespan has to do with 3 or 4.  I chose space and food simply due to the thought that more species moving to higher elevations allows for less space to live, but more prey to be hunted easier.)
 
        
                    
             
        
        
        
Administer varicella vaccine to the health 6-year old child (who does not have evidence of immunity to varicella) was exposed to a confirmed case of varicella 2 days ago. 
Explanation:
It is seen that if a child receives varicella vaccine between 3 to 5 days of exposure, he is safe as disease will not appear in him and would be saved for future infections.
Varicella vaccine is given for prevention against small pox. It is expected once immunised with varicella body will produce antibodies for a span of twenty years or more.
 
        
             
        
        
        
Food chain-  is a diagram that shows how food energy moves from one organism to another in an environment. It begins with the plant life and ends with animal life. Plants get eaten by animals  and animals eat other animals. 
        
             
        
        
        
Answer:
parathyroidoma
Explanation:
The condition where the parathyroid hormone is produces excessively is termed as Hyperparathyroidism. This condition arises when the balance between the calcium and phosphorus gets disturbed. The calcium and phosphorus balance is affected in following two cases –  
a)	When the parathyroid gland is not working properly due to its own problem usually termed as hyperparathyroidism or more specifically primary hyperparathyroidism
b)	When the parathyroid gland is not working properly due to any other disease in the body affecting the functioning of parathyroid. It is termed as secondary hyperparathyroidism