Answer:
See the answer below
Explanation:
Person X is feeling a burning sensation in several muscles<u> because of the accumulation of lactic acid due to inadequate oxygen in their system.</u> When oxygen becomes inadequate during exercises, anaerobic respiration takes place to augment the oxygen shortage and this leads to the production of lactic acid which accumulates up in the muscles and gives a burning sensation.
   
Person Y does not feel any burning sensation in their muscles <u>because oxygen is adequate in their system and they do not need to respire anaerobically.</u> <em>Person X exercise regime must have been more rigorous than that of person Y.</em>
 
        
             
        
        
        
Well I won't go to tooooooo much of that detail but the thing is FACT BY ME that everything around u is science and when u learn about ur surroundings it is science...!!!!
        
             
        
        
        
Evolution is the gradual process resulting in the changes in the genetic material of a population over generations. The mechanism that Darwin proposed for evolution is the process of natural selection. Natural selection is the key mechanism of evolution which increases the frequency of advantageous alleles in a population.  Due to the limited resources in nature, organism with heritable traits favoring their survival and reproduction produce more offspring. It causes the population to become adapted to their environment and results in organisms with better survival ability and reproduction. These traits become heritable due to the reproductive advantage and are passed from the parents to the offspring. Over generations, the advantageous heritable trait becomes dominant in the population. It is responsible for the variation in the gene pool of the population which increases their fitness. 
 
        
             
        
        
        
Answer:
D. Aa
Explanation:
Given:
Jill (mother) is heterozygous for gene A --------- i.e Jill = Aa
Jack (father) who is homozygous recessive for gene A-------- i.e Jack = aa
Now if both cross and fertilization occurs, we have:
          A          a
a        Aa        aa
a        Aa        aa
The offsprings are (Aa, Aa, aa, aa)
Nondsijunction is the inability of homologous chromosomes to seperate properly during cell division. Now, we were told that this fertilization undergone nondisjunction in meiosis 1. Hence, both homologous chromosome move into the same daughter cells instead of different daughter cells because separation of homologous chromosome does not occur properly.
Therefore the result of these fertilization of a normal haploid sperm with an egg that had undergone nondisjunction in meiosis yields offspring with genotype Aa of their Mother (Jill).