Answer: DF508 mutation. A Genetic, Hereditary, Autosomal and Recessive Mutation.
Explanation:
Cystic fibrosis (CF) is a recessive autosomal lethal disease, it is most common on Caucasoid populations. Its diagnosis is suggested by the clinical features of chronic obstructive pulmonary disease, persistent pulmonary colonization (particularly with mucoid Pseudomonas strains), meconium ileus, pancreatic insufficiency with or familiarity history of the disease. The FC gene is large, with about 250 Kb of genomic DNA, 27 exons representing about 5% of genomic DNA; encodes a 6.5 kb transcribed mRNA. This mRNA is transcribed into a protein of 1480 amino acid called CFTR (Regulator Transmembrane Conductance Cystic Fibrosis). When a three-base pair deletion, adenosine-thymine-thymine (ATT) identified in the CFTR gene, exon 10, it results in the loss of a single amino acid phenylalanine at position 508 of the protein. This mutation is called DF508; “D” stands for deletion and “F” for phenylalanine amino acid. 
 
        
             
        
        
        
Answer:
Umm...I'm not sure if this is a question where there is MC but if not, the the answer would most likely be, "By actually doing then saying"
Explanation:
 
        
             
        
        
        
20. The answer is 1 (Precambrian)
21. The answer is 4 (Pennsylvanian)
22. The answer is 2 (Bony Fishes, Dinosaurs, and Mammals)
23. The answer is 2 (Reptiles)
        
             
        
        
        
They are primary subtractive colours, because each of them can be formed by subtracting  a primary additive colour from the white light (blue, green, and red).