<span>Point mutations are of two types: Substitutions of bases that are the change of one base of DNA by another. And Transitions that are replaced on a pyrrhic basis by another pyrrhic or a pyrimidine by another pyrimidine. Transversions: substitution of a pyrrhic base by another pyrimidine or vice versa. These mutations are negative because they affect only one of the nucleotides, and therefore, only one triplet of bases are affected. When the mutation does not affect the individual it is a silent mutation. Chromosomal mutations Changes in the structure of the diploid chromosomes, where one of the chromosomes has a mutation, will have another normal. They can hinder the process of meiosis in the carrier since it hinders the correct pairing of the homologous chromosomes. It would produce an unfeasible offspring or with mutations.</span>
        
                    
             
        
        
        
D is the correct answer since all others are highly unlikely.
        
             
        
        
        
I think the answer is sperm or eggs? i'd need context
        
             
        
        
        
Designing efficacious norovirus vaccines remains a major challenge due to several factors: 
(1) the extreme genetic variability within the norovirus family and within genogroups
(2) the rapid evolution of antigenically dissimilar pandemic GII.4 norovirus strains
(3) the lack of lasting immunity upon natural exposure to noroviruses in at least a proportion of the population.
 
        
             
        
        
        
<u>Answer:</u>
An article that is undergoing peer-review  is read carefully and checked by other scientists.
<u>Explanation:</u>
- Peer-review means reviewing the writer academic work, reports or ideas by the people called as experts in the same field before the writer work is published. Peer-review generally takes about 3-4 weeks. 
- There are general 10 steps for the peer-review and they are submission of idea, editorial office assessment, appraisal by editor in chief, editor in chief assign to an associate editor, call for reviewers, invitation response, review of document, review evaluation, decision making, send to publish.