Antibiotics that kill large numbers of gram-negative bacteria are primarily aminoglycosides and some higher generation cephalosporins. The major medical concern in antibiotic usage is antimicrobial resistance which can arise with improper use of antibiotics. On the other hand, higher generation antibiotics that are proven bactericidal can have more detrimental adverse effects for the patient.
1/2 of a radioactive substance will remain after 3 half lives.
A simple example to illustrate genotype as distinct from phenotype is the flower colour in pea plants (see Gregor Mendel). There are three available genotypes, PP (homozygous dominant), Pp (heterozygous), and pp (homozygous recessive).
